diff --git a/lib/English.rb b/lib/English.rb
index 838e5afc74932d..0c17229682f397 100644
--- a/lib/English.rb
+++ b/lib/English.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #  Include the English library file in a Ruby script, and you can
 #  reference the global variables such as \VAR{\$\_} using less
 #  cryptic names, listed in the following table.% \vref{tab:english}.
diff --git a/lib/abbrev.rb b/lib/abbrev.rb
index 2c07fb5cf9f6e9..2eac293c30d638 100644
--- a/lib/abbrev.rb
+++ b/lib/abbrev.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright (c) 2001,2003 Akinori MUSHA <knu@iDaemons.org>
 #
diff --git a/lib/base64.rb b/lib/base64.rb
index bf33124562d6d7..a08941af9249a0 100644
--- a/lib/base64.rb
+++ b/lib/base64.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # = base64.rb: methods for base64-encoding and -decoding strings
 #
diff --git a/lib/benchmark.rb b/lib/benchmark.rb
index 1e2b8d2d382224..3aeed0c9a68435 100644
--- a/lib/benchmark.rb
+++ b/lib/benchmark.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # benchmark.rb - a performance benchmarking library
 #
diff --git a/lib/cgi.rb b/lib/cgi.rb
index 51f465ea181275..167b76cef7e9a3 100644
--- a/lib/cgi.rb
+++ b/lib/cgi.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # cgi.rb - cgi support library
 #
diff --git a/lib/cgi/cookie.rb b/lib/cgi/cookie.rb
index f92e535bb86e4c..ffd88b8edb0dcc 100644
--- a/lib/cgi/cookie.rb
+++ b/lib/cgi/cookie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'cgi/util'
 class CGI
   # Class representing an HTTP cookie.
diff --git a/lib/cgi/core.rb b/lib/cgi/core.rb
index b81f9153796dad..1a741dcd7665ce 100644
--- a/lib/cgi/core.rb
+++ b/lib/cgi/core.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Methods for generating HTML, parsing CGI-related parameters, and
 # generating HTTP responses.
diff --git a/lib/cgi/html.rb b/lib/cgi/html.rb
index db47bb8266568b..4b9e577b3280b1 100644
--- a/lib/cgi/html.rb
+++ b/lib/cgi/html.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class CGI
   # Base module for HTML-generation mixins.
   #
diff --git a/lib/cgi/session.rb b/lib/cgi/session.rb
index 8d747f0dc7e70d..d44a5f84b088d1 100644
--- a/lib/cgi/session.rb
+++ b/lib/cgi/session.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # cgi/session.rb - session support for cgi scripts
 #
diff --git a/lib/cgi/session/pstore.rb b/lib/cgi/session/pstore.rb
index 75343149e12dce..2dfb72bdceb0a1 100644
--- a/lib/cgi/session/pstore.rb
+++ b/lib/cgi/session/pstore.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # cgi/session/pstore.rb - persistent storage of marshalled session data
 #
diff --git a/lib/cgi/util.rb b/lib/cgi/util.rb
index 3d7db8f2c87641..c2327072398432 100644
--- a/lib/cgi/util.rb
+++ b/lib/cgi/util.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class CGI; module Util; end; extend Util; end
 module CGI::Util
   @@accept_charset="UTF-8" unless defined?(@@accept_charset)
diff --git a/lib/cmath.rb b/lib/cmath.rb
index 9d1e2c2ebf082e..41ab06e77c7e52 100644
--- a/lib/cmath.rb
+++ b/lib/cmath.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # = Trigonometric and transcendental functions for complex numbers.
 #
diff --git a/lib/debug.rb b/lib/debug.rb
index 05614e3f2bdb76..5d754d8ebb9324 100644
--- a/lib/debug.rb
+++ b/lib/debug.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
 # Copyright (C) 2000  Information-technology Promotion Agency, Japan
 # Copyright (C) 2000-2003  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
diff --git a/lib/delegate.rb b/lib/delegate.rb
index 7a6a2a7a7bded2..4ce3c53cc9d916 100644
--- a/lib/delegate.rb
+++ b/lib/delegate.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = delegate -- Support for the Delegation Pattern
 #
 # Documentation by James Edward Gray II and Gavin Sinclair
diff --git a/lib/drb.rb b/lib/drb.rb
index 93cc811e14c563..2bb4716fa22d2a 100644
--- a/lib/drb.rb
+++ b/lib/drb.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: false
 require 'drb/drb'
 
diff --git a/lib/drb/acl.rb b/lib/drb/acl.rb
index 72e034e960e984..520b7df71d1604 100644
--- a/lib/drb/acl.rb
+++ b/lib/drb/acl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # Copyright (c) 2000,2002,2003 Masatoshi SEKI
 #
 # acl.rb is copyrighted free software by Masatoshi SEKI.
diff --git a/lib/drb/drb.rb b/lib/drb/drb.rb
index 456d0fbfa02d7c..8011660156d1ca 100644
--- a/lib/drb/drb.rb
+++ b/lib/drb/drb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # = drb/drb.rb
 #
diff --git a/lib/drb/eq.rb b/lib/drb/eq.rb
index 553f30c598a49c..15ca5cae42aa32 100644
--- a/lib/drb/eq.rb
+++ b/lib/drb/eq.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module DRb
   class DRbObject # :nodoc:
     def ==(other)
diff --git a/lib/drb/extserv.rb b/lib/drb/extserv.rb
index 327b553a25f776..1cb1be47099b85 100644
--- a/lib/drb/extserv.rb
+++ b/lib/drb/extserv.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 =begin
  external service
         Copyright (c) 2000,2002 Masatoshi SEKI
diff --git a/lib/drb/extservm.rb b/lib/drb/extservm.rb
index 7228939d587055..e2637aa62c22d4 100644
--- a/lib/drb/extservm.rb
+++ b/lib/drb/extservm.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 =begin
  external service manager
         Copyright (c) 2000 Masatoshi SEKI
diff --git a/lib/drb/gw.rb b/lib/drb/gw.rb
index b3568ab08d6e26..d00050764456d3 100644
--- a/lib/drb/gw.rb
+++ b/lib/drb/gw.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'monitor'
 
diff --git a/lib/drb/invokemethod.rb b/lib/drb/invokemethod.rb
index 71ebec11f619c4..0fae6d52b6a1c8 100644
--- a/lib/drb/invokemethod.rb
+++ b/lib/drb/invokemethod.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # for ruby-1.8.0
 
 module DRb # :nodoc: all
diff --git a/lib/drb/observer.rb b/lib/drb/observer.rb
index cab9ebc60b03d7..3ee15331a1fd8f 100644
--- a/lib/drb/observer.rb
+++ b/lib/drb/observer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'observer'
 
 module DRb
diff --git a/lib/drb/ssl.rb b/lib/drb/ssl.rb
index efd8271a7819e8..8d2724e736eb24 100644
--- a/lib/drb/ssl.rb
+++ b/lib/drb/ssl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'socket'
 require 'openssl'
 require 'drb/drb'
diff --git a/lib/drb/timeridconv.rb b/lib/drb/timeridconv.rb
index 4ea3035f39e017..e83eb727657b3e 100644
--- a/lib/drb/timeridconv.rb
+++ b/lib/drb/timeridconv.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'monitor'
 
diff --git a/lib/drb/unix.rb b/lib/drb/unix.rb
index 637ea7cf6f8f49..adacf6df5b7c27 100644
--- a/lib/drb/unix.rb
+++ b/lib/drb/unix.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'socket'
 require 'drb/drb'
 require 'tmpdir'
diff --git a/lib/e2mmap.rb b/lib/e2mmap.rb
index 1eb5b51678e574..a9990b5ec56c74 100644
--- a/lib/e2mmap.rb
+++ b/lib/e2mmap.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #--
 #   e2mmap.rb - for Ruby 1.1
diff --git a/lib/erb.rb b/lib/erb.rb
index 7b328bffb051cd..b876ca46252f7b 100644
--- a/lib/erb.rb
+++ b/lib/erb.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 # = ERB -- Ruby Templating
 #
 # Author:: Masatoshi SEKI
diff --git a/lib/fileutils.rb b/lib/fileutils.rb
index 1468d663619696..748ebd763795e1 100644
--- a/lib/fileutils.rb
+++ b/lib/fileutils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # = fileutils.rb
 #
diff --git a/lib/find.rb b/lib/find.rb
index 55783a569503d7..aa7a3c082b38be 100644
--- a/lib/find.rb
+++ b/lib/find.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # find.rb: the Find module for processing all files under a given directory.
 #
diff --git a/lib/forwardable.rb b/lib/forwardable.rb
index c24c8d863053a0..cd15eeab0c5264 100644
--- a/lib/forwardable.rb
+++ b/lib/forwardable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   forwardable.rb -
 #       $Release Version: 1.1$
diff --git a/lib/getoptlong.rb b/lib/getoptlong.rb
index cf635f04389a07..e81493ea50f252 100644
--- a/lib/getoptlong.rb
+++ b/lib/getoptlong.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # GetoptLong for Ruby
 #
diff --git a/lib/ipaddr.rb b/lib/ipaddr.rb
index b0df4d3e6f7571..64d2a8162d5d18 100644
--- a/lib/ipaddr.rb
+++ b/lib/ipaddr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # ipaddr.rb - A class to manipulate an IP address
 #
diff --git a/lib/irb.rb b/lib/irb.rb
index 51961db20cf95c..b9b39c9f28e299 100644
--- a/lib/irb.rb
+++ b/lib/irb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb.rb - irb main module
 #       $Release Version: 0.9.6 $
diff --git a/lib/irb/cmd/chws.rb b/lib/irb/cmd/chws.rb
index 8c0260627e4ef6..606e0c52a97958 100644
--- a/lib/irb/cmd/chws.rb
+++ b/lib/irb/cmd/chws.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   change-ws.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/cmd/fork.rb b/lib/irb/cmd/fork.rb
index 1e02edac63846f..552c3962f61548 100644
--- a/lib/irb/cmd/fork.rb
+++ b/lib/irb/cmd/fork.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   fork.rb -
 #   	$Release Version: 0.9.6 $
diff --git a/lib/irb/cmd/help.rb b/lib/irb/cmd/help.rb
index 76e299fc20fa9f..7a09c396e114a1 100644
--- a/lib/irb/cmd/help.rb
+++ b/lib/irb/cmd/help.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   help.rb - helper using ri
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/cmd/load.rb b/lib/irb/cmd/load.rb
index acda9d0c8c852a..e3b84dad79c3f2 100644
--- a/lib/irb/cmd/load.rb
+++ b/lib/irb/cmd/load.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   load.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/cmd/nop.rb b/lib/irb/cmd/nop.rb
index 60379f016a4abf..9cf4337c286ccf 100644
--- a/lib/irb/cmd/nop.rb
+++ b/lib/irb/cmd/nop.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   nop.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/cmd/pushws.rb b/lib/irb/cmd/pushws.rb
index 0726a4377e5810..aa14430ce4c0d0 100644
--- a/lib/irb/cmd/pushws.rb
+++ b/lib/irb/cmd/pushws.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   change-ws.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/cmd/subirb.rb b/lib/irb/cmd/subirb.rb
index ccf4fc4bcd43a0..f29548b88fde2c 100644
--- a/lib/irb/cmd/subirb.rb
+++ b/lib/irb/cmd/subirb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #   multi.rb -
 #   	$Release Version: 0.9.6$
 #   	$Revision$
diff --git a/lib/irb/completion.rb b/lib/irb/completion.rb
index 2d47f33d66d526..e7499a8e2b1225 100644
--- a/lib/irb/completion.rb
+++ b/lib/irb/completion.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/completor.rb -
 #   	$Release Version: 0.9$
diff --git a/lib/irb/context.rb b/lib/irb/context.rb
index 9cf9600f021103..4cf61289307d5a 100644
--- a/lib/irb/context.rb
+++ b/lib/irb/context.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/context.rb - irb context
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ext/change-ws.rb b/lib/irb/ext/change-ws.rb
index 0ae9097285a3d5..94bfe62bc00f94 100644
--- a/lib/irb/ext/change-ws.rb
+++ b/lib/irb/ext/change-ws.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/ext/cb.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ext/history.rb b/lib/irb/ext/history.rb
index d8378753f2e243..62363b13f436f6 100644
--- a/lib/irb/ext/history.rb
+++ b/lib/irb/ext/history.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   history.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ext/loader.rb b/lib/irb/ext/loader.rb
index 821538cd4470cc..840226db30d66f 100644
--- a/lib/irb/ext/loader.rb
+++ b/lib/irb/ext/loader.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   loader.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ext/math-mode.rb b/lib/irb/ext/math-mode.rb
index 01bd24a1574aa7..e409dbdc6a8638 100644
--- a/lib/irb/ext/math-mode.rb
+++ b/lib/irb/ext/math-mode.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   math-mode.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ext/multi-irb.rb b/lib/irb/ext/multi-irb.rb
index 52f6fda733d650..982a319611f73a 100644
--- a/lib/irb/ext/multi-irb.rb
+++ b/lib/irb/ext/multi-irb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/multi-irb.rb - multiple irb module
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ext/save-history.rb b/lib/irb/ext/save-history.rb
index 4477d18e1a6d6d..236f00fb930b93 100644
--- a/lib/irb/ext/save-history.rb
+++ b/lib/irb/ext/save-history.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #   save-history.rb -
 #   	$Release Version: 0.9.6$
 #   	$Revision$
diff --git a/lib/irb/ext/tracer.rb b/lib/irb/ext/tracer.rb
index c145cf5b4f5d08..200f77e3412d9b 100644
--- a/lib/irb/ext/tracer.rb
+++ b/lib/irb/ext/tracer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/lib/tracer.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ext/use-loader.rb b/lib/irb/ext/use-loader.rb
index 99e76b722f713c..571dd25d17aed7 100644
--- a/lib/irb/ext/use-loader.rb
+++ b/lib/irb/ext/use-loader.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   use-loader.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ext/workspaces.rb b/lib/irb/ext/workspaces.rb
index 4237037271fc59..5bd72c194f102a 100644
--- a/lib/irb/ext/workspaces.rb
+++ b/lib/irb/ext/workspaces.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   push-ws.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/extend-command.rb b/lib/irb/extend-command.rb
index a9326272ffbaee..6f15e6403a4152 100644
--- a/lib/irb/extend-command.rb
+++ b/lib/irb/extend-command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/extend-command.rb - irb extend command
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/frame.rb b/lib/irb/frame.rb
index 64dd63dddf9c91..60738092491861 100644
--- a/lib/irb/frame.rb
+++ b/lib/irb/frame.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   frame.rb -
 #   	$Release Version: 0.9$
diff --git a/lib/irb/help.rb b/lib/irb/help.rb
index b9ebfb1ae57962..a4264ab4abb3ea 100644
--- a/lib/irb/help.rb
+++ b/lib/irb/help.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/help.rb - print usage module
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/init.rb b/lib/irb/init.rb
index af9c363a977cc6..1184db15ea7a21 100644
--- a/lib/irb/init.rb
+++ b/lib/irb/init.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/init.rb - irb initialize module
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/input-method.rb b/lib/irb/input-method.rb
index 4ea3f585f8feb7..f7b1aac3bf3c27 100644
--- a/lib/irb/input-method.rb
+++ b/lib/irb/input-method.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/input-method.rb - input methods used irb
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/inspector.rb b/lib/irb/inspector.rb
index f09b12927af94c..f6f76712b816f0 100644
--- a/lib/irb/inspector.rb
+++ b/lib/irb/inspector.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/inspector.rb - inspect methods
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/lc/error.rb b/lib/irb/lc/error.rb
index c0c6c30d79dcbd..6623f82d84763f 100644
--- a/lib/irb/lc/error.rb
+++ b/lib/irb/lc/error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/lc/error.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/lc/ja/encoding_aliases.rb b/lib/irb/lc/ja/encoding_aliases.rb
index 5bef32e20e60aa..c534bf0feff0fc 100644
--- a/lib/irb/lc/ja/encoding_aliases.rb
+++ b/lib/irb/lc/ja/encoding_aliases.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # :stopdoc:
 module IRB
   class Locale
diff --git a/lib/irb/lc/ja/error.rb b/lib/irb/lc/ja/error.rb
index 4f09d781cbee6d..919363154c0ebe 100644
--- a/lib/irb/lc/ja/error.rb
+++ b/lib/irb/lc/ja/error.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #   irb/lc/ja/error.rb -
 #   	$Release Version: 0.9.6$
 #   	$Revision$
diff --git a/lib/irb/locale.rb b/lib/irb/locale.rb
index 9f40188171afc9..df540c8cbb14ad 100644
--- a/lib/irb/locale.rb
+++ b/lib/irb/locale.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/locale.rb - internationalization module
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/magic-file.rb b/lib/irb/magic-file.rb
index 339ed60b6b0c2b..2dee6846571496 100644
--- a/lib/irb/magic-file.rb
+++ b/lib/irb/magic-file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module IRB
   class << (MagicFile = Object.new)
     # see parser_magic_comment in parse.y
diff --git a/lib/irb/notifier.rb b/lib/irb/notifier.rb
index d5981df2bf4fd2..9d8de82e695aa1 100644
--- a/lib/irb/notifier.rb
+++ b/lib/irb/notifier.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   notifier.rb - output methods used by irb
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/output-method.rb b/lib/irb/output-method.rb
index e0ba25f3e41a15..7d648516987eb0 100644
--- a/lib/irb/output-method.rb
+++ b/lib/irb/output-method.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   output-method.rb - output methods used by irb
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ruby-lex.rb b/lib/irb/ruby-lex.rb
index 7189307e0ac82c..b1138cd77d96e3 100644
--- a/lib/irb/ruby-lex.rb
+++ b/lib/irb/ruby-lex.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/ruby-lex.rb - ruby lexcal analyzer
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ruby-token.rb b/lib/irb/ruby-token.rb
index a80d81c9a55713..af53d3c93b6496 100644
--- a/lib/irb/ruby-token.rb
+++ b/lib/irb/ruby-token.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/ruby-token.rb - ruby tokens
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/slex.rb b/lib/irb/slex.rb
index f6c2bd92f55daf..68174771a70ae5 100644
--- a/lib/irb/slex.rb
+++ b/lib/irb/slex.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/slex.rb - simple lex analyzer
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/src_encoding.rb b/lib/irb/src_encoding.rb
index 958cef104c61e6..32f997fc7c7f26 100644
--- a/lib/irb/src_encoding.rb
+++ b/lib/irb/src_encoding.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # DO NOT WRITE ANY MAGIC COMMENT HERE.
 def default_src_encoding
   return __ENCODING__
diff --git a/lib/irb/version.rb b/lib/irb/version.rb
index bb998db3dd2ca7..094cb33c05eefb 100644
--- a/lib/irb/version.rb
+++ b/lib/irb/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/version.rb - irb version definition file
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/workspace.rb b/lib/irb/workspace.rb
index e05c3bbc96d313..ac3e369430f609 100644
--- a/lib/irb/workspace.rb
+++ b/lib/irb/workspace.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/workspace-binding.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/ws-for-case-2.rb b/lib/irb/ws-for-case-2.rb
index 9f3af49f30a848..eb173fddca44b0 100644
--- a/lib/irb/ws-for-case-2.rb
+++ b/lib/irb/ws-for-case-2.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   irb/ws-for-case-2.rb -
 #   	$Release Version: 0.9.6$
diff --git a/lib/irb/xmp.rb b/lib/irb/xmp.rb
index 449f04328badbd..3234cff7f3f030 100644
--- a/lib/irb/xmp.rb
+++ b/lib/irb/xmp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   xmp.rb - irb version of gotoken xmp
 #   	$Release Version: 0.9$
diff --git a/lib/logger.rb b/lib/logger.rb
index 77b08fe20446ef..2246673b0973e8 100644
--- a/lib/logger.rb
+++ b/lib/logger.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # logger.rb - simple logging utility
 # Copyright (C) 2000-2003, 2005, 2008, 2011  NAKAMURA, Hiroshi <nahi@ruby-lang.org>.
 #
diff --git a/lib/mathn.rb b/lib/mathn.rb
index 315e5438d77310..d07388bc26b7d2 100644
--- a/lib/mathn.rb
+++ b/lib/mathn.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # $Release Version: 0.5 $
 # $Revision: 1.1.1.1.4.1 $
diff --git a/lib/matrix.rb b/lib/matrix.rb
index 2b87f057ad8adf..fe61b6d120b671 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 #
 # = matrix.rb
 #
diff --git a/lib/matrix/eigenvalue_decomposition.rb b/lib/matrix/eigenvalue_decomposition.rb
index 6c3b794f33e679..919db9e83d2976 100644
--- a/lib/matrix/eigenvalue_decomposition.rb
+++ b/lib/matrix/eigenvalue_decomposition.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Matrix
   # Adapted from JAMA: http://math.nist.gov/javanumerics/jama/
 
diff --git a/lib/matrix/lup_decomposition.rb b/lib/matrix/lup_decomposition.rb
index 30f3276253545b..9c1998fd36007b 100644
--- a/lib/matrix/lup_decomposition.rb
+++ b/lib/matrix/lup_decomposition.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Matrix
   # Adapted from JAMA: http://math.nist.gov/javanumerics/jama/
 
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index d8bc1b525d88fd..2904dc05899c91 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 # frozen-string-literal: false
 # module to create Makefile for extension modules
 # invoke like: ruby -r mkmf extconf.rb
diff --git a/lib/monitor.rb b/lib/monitor.rb
index e0491ec054d118..73741f8ddb6021 100644
--- a/lib/monitor.rb
+++ b/lib/monitor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = monitor.rb
 #
 # Copyright (C) 2001  Shugo Maeda <shugo@ruby-lang.org>
diff --git a/lib/mutex_m.rb b/lib/mutex_m.rb
index 6698cb5ac6175a..627355151e7533 100644
--- a/lib/mutex_m.rb
+++ b/lib/mutex_m.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   mutex_m.rb -
 #       $Release Version: 3.0$
diff --git a/lib/net/http.rb b/lib/net/http.rb
index 70f5165e91228d..eb08edf0f7f4cb 100644
--- a/lib/net/http.rb
+++ b/lib/net/http.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # = net/http.rb
 #
diff --git a/lib/net/http/backward.rb b/lib/net/http/backward.rb
index faf47b8489e827..9e24eae32c40ee 100644
--- a/lib/net/http/backward.rb
+++ b/lib/net/http/backward.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # for backward compatibility
 
 # :enddoc:
diff --git a/lib/net/http/exceptions.rb b/lib/net/http/exceptions.rb
index 6c5d81cb044807..0d345266167201 100644
--- a/lib/net/http/exceptions.rb
+++ b/lib/net/http/exceptions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # Net::HTTP exception class.
 # You cannot use Net::HTTPExceptions directly; instead, you must use
 # its subclasses.
diff --git a/lib/net/http/generic_request.rb b/lib/net/http/generic_request.rb
index 9b7d28757d745a..19602da27cb3b7 100644
--- a/lib/net/http/generic_request.rb
+++ b/lib/net/http/generic_request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # HTTPGenericRequest is the parent of the HTTPRequest class.
 # Do not use this directly; use a subclass of HTTPRequest.
 #
diff --git a/lib/net/http/header.rb b/lib/net/http/header.rb
index 8afa32a422b59f..a911d5d255f171 100644
--- a/lib/net/http/header.rb
+++ b/lib/net/http/header.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # The HTTPHeader module defines methods for reading and writing
 # HTTP headers.
 #
diff --git a/lib/net/http/proxy_delta.rb b/lib/net/http/proxy_delta.rb
index b16c9f1ed8d999..a2f770ebdb1b09 100644
--- a/lib/net/http/proxy_delta.rb
+++ b/lib/net/http/proxy_delta.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Net::HTTP::ProxyDelta   #:nodoc: internal use only
   private
 
diff --git a/lib/net/http/request.rb b/lib/net/http/request.rb
index e8b0f48fccfe01..1e86f3e4b47365 100644
--- a/lib/net/http/request.rb
+++ b/lib/net/http/request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # HTTP request class.
 # This class wraps together the request header and the request path.
 # You cannot use this class directly. Instead, you should use one of its
diff --git a/lib/net/http/requests.rb b/lib/net/http/requests.rb
index c1f8360479845a..d4c80a3812c73b 100644
--- a/lib/net/http/requests.rb
+++ b/lib/net/http/requests.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # HTTP/1.1 methods --- RFC2616
 #
diff --git a/lib/net/http/response.rb b/lib/net/http/response.rb
index f51d6b137379f1..349812834fef7d 100644
--- a/lib/net/http/response.rb
+++ b/lib/net/http/response.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # HTTP response class.
 #
 # This class wraps together the response header and the response body (the
diff --git a/lib/net/http/responses.rb b/lib/net/http/responses.rb
index 284bfcfe7ffbf5..a5b8ddc68b7536 100644
--- a/lib/net/http/responses.rb
+++ b/lib/net/http/responses.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # :stopdoc:
 class Net::HTTPUnknownResponse < Net::HTTPResponse
   HAS_BODY = true
diff --git a/lib/net/https.rb b/lib/net/https.rb
index 4351cae36014af..58cb6ddf192621 100644
--- a/lib/net/https.rb
+++ b/lib/net/https.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 =begin
 
 = net/https -- SSL/TLS enhancement for Net::HTTP.
diff --git a/lib/net/pop.rb b/lib/net/pop.rb
index db7192c95ad436..00209fec469d9e 100644
--- a/lib/net/pop.rb
+++ b/lib/net/pop.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = net/pop.rb
 #
 # Copyright (c) 1999-2007 Yukihiro Matsumoto.
diff --git a/lib/net/protocol.rb b/lib/net/protocol.rb
index 28833a25ef707d..b53370931abfcd 100644
--- a/lib/net/protocol.rb
+++ b/lib/net/protocol.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # = net/protocol.rb
 #
diff --git a/lib/net/smtp.rb b/lib/net/smtp.rb
index 64e536a12a84fe..d634274c3ee8b1 100644
--- a/lib/net/smtp.rb
+++ b/lib/net/smtp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = net/smtp.rb
 #
 # Copyright (c) 1999-2007 Yukihiro Matsumoto.
diff --git a/lib/observer.rb b/lib/observer.rb
index 10f2eb0db5a3cc..fa7446f3847c30 100644
--- a/lib/observer.rb
+++ b/lib/observer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Implementation of the _Observer_ object-oriented design pattern.  The
 # following documentation is copied, with modifications, from "Programming
diff --git a/lib/optionparser.rb b/lib/optionparser.rb
index d89a4d22fb0204..4b9b40d82a7cdf 100644
--- a/lib/optionparser.rb
+++ b/lib/optionparser.rb
@@ -1 +1,2 @@
+# frozen_string_literal: false
 require_relative 'optparse'
diff --git a/lib/optparse.rb b/lib/optparse.rb
index 2e8b5971a2a537..49f7ebee9dadb4 100644
--- a/lib/optparse.rb
+++ b/lib/optparse.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # optparse.rb - command-line option analysis with the OptionParser class.
 #
diff --git a/lib/optparse/ac.rb b/lib/optparse/ac.rb
index 6a8626094d1c95..fb0883f97a688b 100644
--- a/lib/optparse/ac.rb
+++ b/lib/optparse/ac.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'optparse'
 
 class OptionParser::AC < OptionParser
diff --git a/lib/optparse/date.rb b/lib/optparse/date.rb
index d680559f3708a1..d6649c83f1abe6 100644
--- a/lib/optparse/date.rb
+++ b/lib/optparse/date.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'optparse'
 require 'date'
 
diff --git a/lib/optparse/shellwords.rb b/lib/optparse/shellwords.rb
index 0422d7c887de8e..bf31701b963319 100644
--- a/lib/optparse/shellwords.rb
+++ b/lib/optparse/shellwords.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # -*- ruby -*-
 
 require 'shellwords'
diff --git a/lib/optparse/time.rb b/lib/optparse/time.rb
index 402cadcf167eab..ffc6ff000d9ef3 100644
--- a/lib/optparse/time.rb
+++ b/lib/optparse/time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'optparse'
 require 'time'
 
diff --git a/lib/optparse/uri.rb b/lib/optparse/uri.rb
index 024dc69eac4bae..51550cf91b150d 100644
--- a/lib/optparse/uri.rb
+++ b/lib/optparse/uri.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # -*- ruby -*-
 
 require 'optparse'
diff --git a/lib/optparse/version.rb b/lib/optparse/version.rb
index 85256774185552..b869d8fe51ed47 100644
--- a/lib/optparse/version.rb
+++ b/lib/optparse/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # OptionParser internal utility
 
 class << OptionParser
diff --git a/lib/ostruct.rb b/lib/ostruct.rb
index 84244b3d9eea17..5aea0465bda8c3 100644
--- a/lib/ostruct.rb
+++ b/lib/ostruct.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # = ostruct.rb: OpenStruct implementation
 #
diff --git a/lib/prime.rb b/lib/prime.rb
index c79b0cfd5fe716..c64c0c2cf180d9 100644
--- a/lib/prime.rb
+++ b/lib/prime.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # = prime.rb
 #
diff --git a/lib/profile.rb b/lib/profile.rb
index 2aeecce908f24e..39f83703707145 100644
--- a/lib/profile.rb
+++ b/lib/profile.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'profiler'
 
 RubyVM::InstructionSequence.compile_option = {
diff --git a/lib/profiler.rb b/lib/profiler.rb
index e53951cbe6e309..ab55e1fe48113a 100644
--- a/lib/profiler.rb
+++ b/lib/profiler.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # Profile provides a way to Profile your Ruby application.
 #
 # Profiling your program is a way of determining which methods are called and
diff --git a/lib/pstore.rb b/lib/pstore.rb
index 02c20c91c79316..2769b250659610 100644
--- a/lib/pstore.rb
+++ b/lib/pstore.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = PStore -- Transactional File Storage for Ruby Objects
 #
 # pstore.rb -
diff --git a/lib/racc/parser.rb b/lib/racc/parser.rb
index f811ab6e781271..0cdb42e49d1428 100644
--- a/lib/racc/parser.rb
+++ b/lib/racc/parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # $originalId: parser.rb,v 1.8 2006/07/06 11:42:07 aamine Exp $
 #
diff --git a/lib/rbconfig/datadir.rb b/lib/rbconfig/datadir.rb
index 9b7eabb4730e70..136162da445586 100644
--- a/lib/rbconfig/datadir.rb
+++ b/lib/rbconfig/datadir.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rdoc.rb b/lib/rdoc.rb
index a99e5dc3099ce3..bdd3b06e2a82bb 100644
--- a/lib/rdoc.rb
+++ b/lib/rdoc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 $DEBUG_RDOC = nil
 
 # :main: README.rdoc
diff --git a/lib/rdoc/alias.rb b/lib/rdoc/alias.rb
index 39d2694817ed4f..1e06fb96e52397 100644
--- a/lib/rdoc/alias.rb
+++ b/lib/rdoc/alias.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Represent an alias, which is an old_name/new_name pair associated with a
 # particular context
diff --git a/lib/rdoc/anon_class.rb b/lib/rdoc/anon_class.rb
index c23d8e5d966b26..098bfdfcf9963f 100644
--- a/lib/rdoc/anon_class.rb
+++ b/lib/rdoc/anon_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # An anonymous class like:
 #
diff --git a/lib/rdoc/any_method.rb b/lib/rdoc/any_method.rb
index ae022d72f82248..16ac8e024e22f5 100644
--- a/lib/rdoc/any_method.rb
+++ b/lib/rdoc/any_method.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # AnyMethod is the base class for objects representing methods
 
diff --git a/lib/rdoc/attr.rb b/lib/rdoc/attr.rb
index 960e1d1107f60f..f77a5c04a72b17 100644
--- a/lib/rdoc/attr.rb
+++ b/lib/rdoc/attr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # An attribute created by \#attr, \#attr_reader, \#attr_writer or
 # \#attr_accessor
diff --git a/lib/rdoc/class_module.rb b/lib/rdoc/class_module.rb
index 71566f050a03d1..5881d6cf244206 100644
--- a/lib/rdoc/class_module.rb
+++ b/lib/rdoc/class_module.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # ClassModule is the base class for objects representing either a class or a
 # module.
diff --git a/lib/rdoc/code_object.rb b/lib/rdoc/code_object.rb
index 4620fa586da65f..dc195cc6acc07f 100644
--- a/lib/rdoc/code_object.rb
+++ b/lib/rdoc/code_object.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Base class for the RDoc code tree.
 #
diff --git a/lib/rdoc/code_objects.rb b/lib/rdoc/code_objects.rb
index f1a626cd2e1086..564849e1d16070 100644
--- a/lib/rdoc/code_objects.rb
+++ b/lib/rdoc/code_objects.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # This file was used to load all the RDoc::CodeObject subclasses at once.  Now
 # autoload handles this.
 
diff --git a/lib/rdoc/comment.rb b/lib/rdoc/comment.rb
index 33ced18b5ac6fb..ebff74223367d1 100644
--- a/lib/rdoc/comment.rb
+++ b/lib/rdoc/comment.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A comment holds the text comment for a RDoc::CodeObject and provides a
 # unified way of cleaning it up and parsing it into an RDoc::Markup::Document.
diff --git a/lib/rdoc/constant.rb b/lib/rdoc/constant.rb
index 97985cbf9986e2..4fd5c5f10ff937 100644
--- a/lib/rdoc/constant.rb
+++ b/lib/rdoc/constant.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A constant
 
diff --git a/lib/rdoc/context.rb b/lib/rdoc/context.rb
index 5eb86ddc92afa3..bc8c8eecf1c2d0 100644
--- a/lib/rdoc/context.rb
+++ b/lib/rdoc/context.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'cgi'
 
 ##
diff --git a/lib/rdoc/context/section.rb b/lib/rdoc/context/section.rb
index 580f07deff8c91..90f184cb8953b0 100644
--- a/lib/rdoc/context/section.rb
+++ b/lib/rdoc/context/section.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A section of documentation like:
 #
diff --git a/lib/rdoc/cross_reference.rb b/lib/rdoc/cross_reference.rb
index 5b08d5202de1dc..0e40d23159f867 100644
--- a/lib/rdoc/cross_reference.rb
+++ b/lib/rdoc/cross_reference.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # RDoc::CrossReference is a reusable way to create cross references for names.
 
diff --git a/lib/rdoc/encoding.rb b/lib/rdoc/encoding.rb
index b3515a435f3b32..5327f9a961c0c8 100644
--- a/lib/rdoc/encoding.rb
+++ b/lib/rdoc/encoding.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 
 ##
 # This class is a wrapper around File IO and Encoding that helps RDoc load
diff --git a/lib/rdoc/erb_partial.rb b/lib/rdoc/erb_partial.rb
index 8359258d2759cd..ebb8cb3117ee99 100644
--- a/lib/rdoc/erb_partial.rb
+++ b/lib/rdoc/erb_partial.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Allows an ERB template to be rendered in the context (binding) of an
 # existing ERB template evaluation.
diff --git a/lib/rdoc/erbio.rb b/lib/rdoc/erbio.rb
index 04a89fbd34817c..a2aaa90e67f607 100644
--- a/lib/rdoc/erbio.rb
+++ b/lib/rdoc/erbio.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'erb'
 
 ##
diff --git a/lib/rdoc/extend.rb b/lib/rdoc/extend.rb
index efa2c69bee00f8..30b51a1dbdebc1 100644
--- a/lib/rdoc/extend.rb
+++ b/lib/rdoc/extend.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A Module extension to a class with \#extend
 #
diff --git a/lib/rdoc/generator.rb b/lib/rdoc/generator.rb
index 7d3989d42f9244..d37d1db61f7a8b 100644
--- a/lib/rdoc/generator.rb
+++ b/lib/rdoc/generator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # RDoc uses generators to turn parsed source code in the form of an
 # RDoc::CodeObject tree into some form of output.  RDoc comes with the HTML
diff --git a/lib/rdoc/generator/darkfish.rb b/lib/rdoc/generator/darkfish.rb
index 024040466db055..18394a2c34ce9f 100644
--- a/lib/rdoc/generator/darkfish.rb
+++ b/lib/rdoc/generator/darkfish.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # -*- mode: ruby; ruby-indent-level: 2; tab-width: 2 -*-
 
 require 'erb'
diff --git a/lib/rdoc/generator/json_index.rb b/lib/rdoc/generator/json_index.rb
index 5318b4cc575ea7..90c68f91a1fff7 100644
--- a/lib/rdoc/generator/json_index.rb
+++ b/lib/rdoc/generator/json_index.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'json'
 begin
   require 'zlib'
diff --git a/lib/rdoc/generator/markup.rb b/lib/rdoc/generator/markup.rb
index 788e5a485df408..3ca423bb69a6ea 100644
--- a/lib/rdoc/generator/markup.rb
+++ b/lib/rdoc/generator/markup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Handle common RDoc::Markup tasks for various CodeObjects
 #
diff --git a/lib/rdoc/generator/pot.rb b/lib/rdoc/generator/pot.rb
index db6f3a03546dcc..e2cf22d7300689 100644
--- a/lib/rdoc/generator/pot.rb
+++ b/lib/rdoc/generator/pot.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Generates a POT file.
 #
diff --git a/lib/rdoc/generator/pot/message_extractor.rb b/lib/rdoc/generator/pot/message_extractor.rb
index ceabc5262adf5f..0dd2497c266bc7 100644
--- a/lib/rdoc/generator/pot/message_extractor.rb
+++ b/lib/rdoc/generator/pot/message_extractor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Extracts message from RDoc::Store
 
diff --git a/lib/rdoc/generator/pot/po.rb b/lib/rdoc/generator/pot/po.rb
index 6a6b5821f35aec..60e14db8311f36 100644
--- a/lib/rdoc/generator/pot/po.rb
+++ b/lib/rdoc/generator/pot/po.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Generates a PO format text
 
diff --git a/lib/rdoc/generator/pot/po_entry.rb b/lib/rdoc/generator/pot/po_entry.rb
index d4cef59ee96461..515d02b48dce60 100644
--- a/lib/rdoc/generator/pot/po_entry.rb
+++ b/lib/rdoc/generator/pot/po_entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A PO entry in PO
 
diff --git a/lib/rdoc/generator/ri.rb b/lib/rdoc/generator/ri.rb
index b9c4141a5e2025..830777e58709b2 100644
--- a/lib/rdoc/generator/ri.rb
+++ b/lib/rdoc/generator/ri.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Generates ri data files
 
diff --git a/lib/rdoc/ghost_method.rb b/lib/rdoc/ghost_method.rb
index 7eb2d931674c1b..a1f75bfe4b63f6 100644
--- a/lib/rdoc/ghost_method.rb
+++ b/lib/rdoc/ghost_method.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # GhostMethod represents a method referenced only by a comment
 
diff --git a/lib/rdoc/i18n.rb b/lib/rdoc/i18n.rb
index 4cccbc66d3b991..20848aad7547f8 100644
--- a/lib/rdoc/i18n.rb
+++ b/lib/rdoc/i18n.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # This module provides i18n realated features.
 
diff --git a/lib/rdoc/i18n/locale.rb b/lib/rdoc/i18n/locale.rb
index e98732e086e53d..735a271bf3149e 100644
--- a/lib/rdoc/i18n/locale.rb
+++ b/lib/rdoc/i18n/locale.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A message container for a locale.
 #
diff --git a/lib/rdoc/i18n/text.rb b/lib/rdoc/i18n/text.rb
index ee5c66a1ffc441..fcfe7611bc86c1 100644
--- a/lib/rdoc/i18n/text.rb
+++ b/lib/rdoc/i18n/text.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # An i18n supported text.
 #
diff --git a/lib/rdoc/include.rb b/lib/rdoc/include.rb
index 75ed9c7bffd1e3..efce43bffbe015 100644
--- a/lib/rdoc/include.rb
+++ b/lib/rdoc/include.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A Module included in a class with \#include
 #
diff --git a/lib/rdoc/known_classes.rb b/lib/rdoc/known_classes.rb
index a04068a435c99f..8d9421255b1231 100644
--- a/lib/rdoc/known_classes.rb
+++ b/lib/rdoc/known_classes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module RDoc
 
   ##
diff --git a/lib/rdoc/markdown.rb b/lib/rdoc/markdown.rb
index 033fc2be6d214e..f3d4bd86d0723a 100644
--- a/lib/rdoc/markdown.rb
+++ b/lib/rdoc/markdown.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 # :markup: markdown
 
 ##
diff --git a/lib/rdoc/markdown/entities.rb b/lib/rdoc/markdown/entities.rb
index 0661abab787887..d32ae51053966e 100644
--- a/lib/rdoc/markdown/entities.rb
+++ b/lib/rdoc/markdown/entities.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # HTML entity name map for RDoc::Markdown
 
diff --git a/lib/rdoc/markdown/literals_1_9.rb b/lib/rdoc/markdown/literals_1_9.rb
index f7bfbe27a132a1..d7a27f12b1a411 100644
--- a/lib/rdoc/markdown/literals_1_9.rb
+++ b/lib/rdoc/markdown/literals_1_9.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 # :markup: markdown
 
 ##
diff --git a/lib/rdoc/markup.rb b/lib/rdoc/markup.rb
index 0e754ff33db1d7..340652259688c0 100644
--- a/lib/rdoc/markup.rb
+++ b/lib/rdoc/markup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # RDoc::Markup parses plain text documents and attempts to decompose them into
 # their constituent parts.  Some of these parts are high-level: paragraphs,
diff --git a/lib/rdoc/markup/attr_changer.rb b/lib/rdoc/markup/attr_changer.rb
index 1772f18b2b264b..9a1a9c8c66ad4e 100644
--- a/lib/rdoc/markup/attr_changer.rb
+++ b/lib/rdoc/markup/attr_changer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class RDoc::Markup
 
   AttrChanger = Struct.new :turn_on, :turn_off # :nodoc:
diff --git a/lib/rdoc/markup/attr_span.rb b/lib/rdoc/markup/attr_span.rb
index b5c1b3b7b7cd46..4d9e5b0217f00b 100644
--- a/lib/rdoc/markup/attr_span.rb
+++ b/lib/rdoc/markup/attr_span.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # An array of attributes which parallels the characters in a string.
 
diff --git a/lib/rdoc/markup/attribute_manager.rb b/lib/rdoc/markup/attribute_manager.rb
index ce4ac76d5b25bb..3296d17af255d6 100644
--- a/lib/rdoc/markup/attribute_manager.rb
+++ b/lib/rdoc/markup/attribute_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Manages changes of attributes in a block of text
 
diff --git a/lib/rdoc/markup/attributes.rb b/lib/rdoc/markup/attributes.rb
index 3423f10ca7a3a9..8776c4ed29367e 100644
--- a/lib/rdoc/markup/attributes.rb
+++ b/lib/rdoc/markup/attributes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # We manage a set of attributes.  Each attribute has a symbol name and a bit
 # value.
diff --git a/lib/rdoc/markup/blank_line.rb b/lib/rdoc/markup/blank_line.rb
index 5da0ac8d813132..2b1ab91b47efc9 100644
--- a/lib/rdoc/markup/blank_line.rb
+++ b/lib/rdoc/markup/blank_line.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # An empty line.  This class is a singleton.
 
diff --git a/lib/rdoc/markup/block_quote.rb b/lib/rdoc/markup/block_quote.rb
index 552f0c4baad350..3be022f9ddabd6 100644
--- a/lib/rdoc/markup/block_quote.rb
+++ b/lib/rdoc/markup/block_quote.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A quoted section which contains markup items.
 
diff --git a/lib/rdoc/markup/document.rb b/lib/rdoc/markup/document.rb
index be93d80eecb89b..0692c3522f018c 100644
--- a/lib/rdoc/markup/document.rb
+++ b/lib/rdoc/markup/document.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A Document containing lists, headings, paragraphs, etc.
 
diff --git a/lib/rdoc/markup/formatter.rb b/lib/rdoc/markup/formatter.rb
index 7661c952395c37..197ff003e3e85a 100644
--- a/lib/rdoc/markup/formatter.rb
+++ b/lib/rdoc/markup/formatter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Base class for RDoc markup formatters
 #
diff --git a/lib/rdoc/markup/formatter_test_case.rb b/lib/rdoc/markup/formatter_test_case.rb
index 6616a7589820f8..776fe00537aa23 100644
--- a/lib/rdoc/markup/formatter_test_case.rb
+++ b/lib/rdoc/markup/formatter_test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'minitest/unit'
 
 ##
diff --git a/lib/rdoc/markup/hard_break.rb b/lib/rdoc/markup/hard_break.rb
index 8445ad26e7f159..5898bfb6449991 100644
--- a/lib/rdoc/markup/hard_break.rb
+++ b/lib/rdoc/markup/hard_break.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A hard-break in the middle of a paragraph.
 
diff --git a/lib/rdoc/markup/heading.rb b/lib/rdoc/markup/heading.rb
index 535e310e54e89f..5229287d5b971e 100644
--- a/lib/rdoc/markup/heading.rb
+++ b/lib/rdoc/markup/heading.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A heading with a level (1-6) and text
 
diff --git a/lib/rdoc/markup/include.rb b/lib/rdoc/markup/include.rb
index a2e89032792707..891be71b8516a4 100644
--- a/lib/rdoc/markup/include.rb
+++ b/lib/rdoc/markup/include.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A file included at generation time.  Objects of this class are created by
 # RDoc::RD for an extension-less include.
diff --git a/lib/rdoc/markup/indented_paragraph.rb b/lib/rdoc/markup/indented_paragraph.rb
index 1b8a8c725d0d66..56a96bd3c91a59 100644
--- a/lib/rdoc/markup/indented_paragraph.rb
+++ b/lib/rdoc/markup/indented_paragraph.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # An Indented Paragraph of text
 
diff --git a/lib/rdoc/markup/inline.rb b/lib/rdoc/markup/inline.rb
index fb3ab5c74d1dc8..58072fef0656b6 100644
--- a/lib/rdoc/markup/inline.rb
+++ b/lib/rdoc/markup/inline.rb
@@ -1 +1,2 @@
+# frozen_string_literal: false
 warn "requiring rdoc/markup/inline is deprecated and will be removed in RDoc 4." if $-w
diff --git a/lib/rdoc/markup/list.rb b/lib/rdoc/markup/list.rb
index 89b7fc20fa2e21..bcaea7d7c13d8f 100644
--- a/lib/rdoc/markup/list.rb
+++ b/lib/rdoc/markup/list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A List is a homogeneous set of ListItems.
 #
diff --git a/lib/rdoc/markup/list_item.rb b/lib/rdoc/markup/list_item.rb
index c5e59fe1672946..115ec0412c023a 100644
--- a/lib/rdoc/markup/list_item.rb
+++ b/lib/rdoc/markup/list_item.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # An item within a List that contains paragraphs, headings, etc.
 #
diff --git a/lib/rdoc/markup/paragraph.rb b/lib/rdoc/markup/paragraph.rb
index 7180729f75474b..fefa12f9eff063 100644
--- a/lib/rdoc/markup/paragraph.rb
+++ b/lib/rdoc/markup/paragraph.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A Paragraph of text
 
diff --git a/lib/rdoc/markup/parser.rb b/lib/rdoc/markup/parser.rb
index cc828a4513042c..2f8b7628e27153 100644
--- a/lib/rdoc/markup/parser.rb
+++ b/lib/rdoc/markup/parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'strscan'
 
 ##
diff --git a/lib/rdoc/markup/pre_process.rb b/lib/rdoc/markup/pre_process.rb
index 01fb293462c99c..d7cef3615888a7 100644
--- a/lib/rdoc/markup/pre_process.rb
+++ b/lib/rdoc/markup/pre_process.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Handle common directives that can occur in a block of text:
 #
diff --git a/lib/rdoc/markup/raw.rb b/lib/rdoc/markup/raw.rb
index e11e8efff43248..8012d2cea6c863 100644
--- a/lib/rdoc/markup/raw.rb
+++ b/lib/rdoc/markup/raw.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A section of text that is added to the output document as-is
 
diff --git a/lib/rdoc/markup/rule.rb b/lib/rdoc/markup/rule.rb
index b778f2bc090792..b96d4fb2933c86 100644
--- a/lib/rdoc/markup/rule.rb
+++ b/lib/rdoc/markup/rule.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A horizontal rule with a weight
 
diff --git a/lib/rdoc/markup/special.rb b/lib/rdoc/markup/special.rb
index 1c0fc03eea5138..4d834b9e378458 100644
--- a/lib/rdoc/markup/special.rb
+++ b/lib/rdoc/markup/special.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Hold details of a special sequence
 
diff --git a/lib/rdoc/markup/text_formatter_test_case.rb b/lib/rdoc/markup/text_formatter_test_case.rb
index 4abf42563b58ad..1c8882aa36e854 100644
--- a/lib/rdoc/markup/text_formatter_test_case.rb
+++ b/lib/rdoc/markup/text_formatter_test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Test case for creating new plain-text RDoc::Markup formatters.  See also
 # RDoc::Markup::FormatterTestCase
diff --git a/lib/rdoc/markup/to_ansi.rb b/lib/rdoc/markup/to_ansi.rb
index 4d439ce88db278..56cd1fe44612be 100644
--- a/lib/rdoc/markup/to_ansi.rb
+++ b/lib/rdoc/markup/to_ansi.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Outputs RDoc markup with vibrant ANSI color!
 
diff --git a/lib/rdoc/markup/to_bs.rb b/lib/rdoc/markup/to_bs.rb
index 10c31854d21117..d55f64c5e78571 100644
--- a/lib/rdoc/markup/to_bs.rb
+++ b/lib/rdoc/markup/to_bs.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Outputs RDoc markup with hot backspace action!  You will probably need a
 # pager to use this output format.
diff --git a/lib/rdoc/markup/to_html.rb b/lib/rdoc/markup/to_html.rb
index 2b1216ef2a5d3e..3bf66c2c31ac62 100644
--- a/lib/rdoc/markup/to_html.rb
+++ b/lib/rdoc/markup/to_html.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'cgi'
 
 ##
diff --git a/lib/rdoc/markup/to_html_crossref.rb b/lib/rdoc/markup/to_html_crossref.rb
index d27e0ab6274ef1..3f03c65898d334 100644
--- a/lib/rdoc/markup/to_html_crossref.rb
+++ b/lib/rdoc/markup/to_html_crossref.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Subclass of the RDoc::Markup::ToHtml class that supports looking up method
 # names, classes, etc to create links.  RDoc::CrossReference is used to
diff --git a/lib/rdoc/markup/to_html_snippet.rb b/lib/rdoc/markup/to_html_snippet.rb
index 4ad0a9a4b9b7b9..75c1df94d9afd6 100644
--- a/lib/rdoc/markup/to_html_snippet.rb
+++ b/lib/rdoc/markup/to_html_snippet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Outputs RDoc markup as paragraphs with inline markup only.
 
diff --git a/lib/rdoc/markup/to_joined_paragraph.rb b/lib/rdoc/markup/to_joined_paragraph.rb
index 835841071d37b6..293258c092fcc5 100644
--- a/lib/rdoc/markup/to_joined_paragraph.rb
+++ b/lib/rdoc/markup/to_joined_paragraph.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Joins the parts of an RDoc::Markup::Paragraph into a single String.
 #
diff --git a/lib/rdoc/markup/to_label.rb b/lib/rdoc/markup/to_label.rb
index 6fbe4a3dbddc42..bdf08b7aee9e8c 100644
--- a/lib/rdoc/markup/to_label.rb
+++ b/lib/rdoc/markup/to_label.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'cgi'
 
 ##
diff --git a/lib/rdoc/markup/to_markdown.rb b/lib/rdoc/markup/to_markdown.rb
index d4b15bf41bf3ed..9074547b4c1832 100644
--- a/lib/rdoc/markup/to_markdown.rb
+++ b/lib/rdoc/markup/to_markdown.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # :markup: markdown
 
 ##
diff --git a/lib/rdoc/markup/to_rdoc.rb b/lib/rdoc/markup/to_rdoc.rb
index f16b4ed5a39453..a40c09859f4248 100644
--- a/lib/rdoc/markup/to_rdoc.rb
+++ b/lib/rdoc/markup/to_rdoc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Outputs RDoc markup as RDoc markup! (mostly)
 
diff --git a/lib/rdoc/markup/to_table_of_contents.rb b/lib/rdoc/markup/to_table_of_contents.rb
index 2e0f98cfebb03e..eae7c59d94a117 100644
--- a/lib/rdoc/markup/to_table_of_contents.rb
+++ b/lib/rdoc/markup/to_table_of_contents.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Extracts just the RDoc::Markup::Heading elements from a
 # RDoc::Markup::Document to help build a table of contents
diff --git a/lib/rdoc/markup/to_test.rb b/lib/rdoc/markup/to_test.rb
index c51f64b917b3d0..7b1fa8c630d1ea 100644
--- a/lib/rdoc/markup/to_test.rb
+++ b/lib/rdoc/markup/to_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # This Markup outputter is used for testing purposes.
 
diff --git a/lib/rdoc/markup/to_tt_only.rb b/lib/rdoc/markup/to_tt_only.rb
index e2da20c6f31f65..ba20fcdd003e9a 100644
--- a/lib/rdoc/markup/to_tt_only.rb
+++ b/lib/rdoc/markup/to_tt_only.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Extracts sections of text enclosed in plus, tt or code.  Used to discover
 # undocumented parameters.
diff --git a/lib/rdoc/markup/verbatim.rb b/lib/rdoc/markup/verbatim.rb
index 0ddde675e3a588..a0b1d059284ccb 100644
--- a/lib/rdoc/markup/verbatim.rb
+++ b/lib/rdoc/markup/verbatim.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A section of verbatim text
 
diff --git a/lib/rdoc/meta_method.rb b/lib/rdoc/meta_method.rb
index 68ba8109e0f490..408c089dd19131 100644
--- a/lib/rdoc/meta_method.rb
+++ b/lib/rdoc/meta_method.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # MetaMethod represents a meta-programmed method
 
diff --git a/lib/rdoc/method_attr.rb b/lib/rdoc/method_attr.rb
index a0ea851dc502f6..50eab141be3171 100644
--- a/lib/rdoc/method_attr.rb
+++ b/lib/rdoc/method_attr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Abstract class representing either a method or an attribute.
 
diff --git a/lib/rdoc/mixin.rb b/lib/rdoc/mixin.rb
index 547744f8707577..14f04c15e77060 100644
--- a/lib/rdoc/mixin.rb
+++ b/lib/rdoc/mixin.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A Mixin adds features from a module into another context.  RDoc::Include and
 # RDoc::Extend are both mixins.
diff --git a/lib/rdoc/normal_class.rb b/lib/rdoc/normal_class.rb
index 7589e2686c74bf..eb53e964dd2eb8 100644
--- a/lib/rdoc/normal_class.rb
+++ b/lib/rdoc/normal_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A normal class, neither singleton nor anonymous
 
diff --git a/lib/rdoc/normal_module.rb b/lib/rdoc/normal_module.rb
index 961c431ed6bdc3..d046c8cbfe27d2 100644
--- a/lib/rdoc/normal_module.rb
+++ b/lib/rdoc/normal_module.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A normal module, like NormalClass
 
diff --git a/lib/rdoc/options.rb b/lib/rdoc/options.rb
index 5779d35c44d3f5..17b0bb105dd846 100644
--- a/lib/rdoc/options.rb
+++ b/lib/rdoc/options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'optparse'
 require 'pathname'
 
diff --git a/lib/rdoc/parser.rb b/lib/rdoc/parser.rb
index 4da7f00d3c8f93..9c207edcffe9a9 100644
--- a/lib/rdoc/parser.rb
+++ b/lib/rdoc/parser.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 
 ##
 # A parser is simple a class that subclasses RDoc::Parser and implements #scan
diff --git a/lib/rdoc/parser/c.rb b/lib/rdoc/parser/c.rb
index fd336f5f5ba338..cd139441ba6625 100644
--- a/lib/rdoc/parser/c.rb
+++ b/lib/rdoc/parser/c.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'tsort'
 
 ##
diff --git a/lib/rdoc/parser/changelog.rb b/lib/rdoc/parser/changelog.rb
index a3567c1f81c378..92c8d94ad643e6 100644
--- a/lib/rdoc/parser/changelog.rb
+++ b/lib/rdoc/parser/changelog.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'time'
 
 ##
diff --git a/lib/rdoc/parser/markdown.rb b/lib/rdoc/parser/markdown.rb
index 6fd88cf614eeee..feffb26ced6960 100644
--- a/lib/rdoc/parser/markdown.rb
+++ b/lib/rdoc/parser/markdown.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Parse a Markdown format file.  The parsed RDoc::Markup::Document is attached
 # as a file comment.
diff --git a/lib/rdoc/parser/rd.rb b/lib/rdoc/parser/rd.rb
index 09069ae297bfcb..e6693b9ac8e26c 100644
--- a/lib/rdoc/parser/rd.rb
+++ b/lib/rdoc/parser/rd.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Parse a RD format file.  The parsed RDoc::Markup::Document is attached as a
 # file comment.
diff --git a/lib/rdoc/parser/ruby.rb b/lib/rdoc/parser/ruby.rb
index ce1083edc7de0d..ac7094f48887ae 100644
--- a/lib/rdoc/parser/ruby.rb
+++ b/lib/rdoc/parser/ruby.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # This file contains stuff stolen outright from:
 #
diff --git a/lib/rdoc/parser/ruby_tools.rb b/lib/rdoc/parser/ruby_tools.rb
index 654431ea3023d4..bbca065b5ee8f4 100644
--- a/lib/rdoc/parser/ruby_tools.rb
+++ b/lib/rdoc/parser/ruby_tools.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Collection of methods for writing parsers against RDoc::RubyLex and
 # RDoc::RubyToken
diff --git a/lib/rdoc/parser/simple.rb b/lib/rdoc/parser/simple.rb
index 65cfc1b2e7c679..73bb7bdffb943c 100644
--- a/lib/rdoc/parser/simple.rb
+++ b/lib/rdoc/parser/simple.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Parse a non-source file. We basically take the whole thing as one big
 # comment.
diff --git a/lib/rdoc/parser/text.rb b/lib/rdoc/parser/text.rb
index f9733135513b88..1a13fd118655d9 100644
--- a/lib/rdoc/parser/text.rb
+++ b/lib/rdoc/parser/text.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Indicates this parser is text and doesn't contain code constructs.
 #
diff --git a/lib/rdoc/rd.rb b/lib/rdoc/rd.rb
index 28c5d286e0f9fc..39af3294f5132b 100644
--- a/lib/rdoc/rd.rb
+++ b/lib/rdoc/rd.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # RDoc::RD implements the RD format from the rdtool gem.
 #
diff --git a/lib/rdoc/rd/block_parser.rb b/lib/rdoc/rd/block_parser.rb
index ac754f420030a3..111ba90fdc3a39 100644
--- a/lib/rdoc/rd/block_parser.rb
+++ b/lib/rdoc/rd/block_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # DO NOT MODIFY!!!!
 # This file is automatically generated by Racc 1.4.12
diff --git a/lib/rdoc/rd/inline.rb b/lib/rdoc/rd/inline.rb
index ee724fb80f51a5..011ec67e33910e 100644
--- a/lib/rdoc/rd/inline.rb
+++ b/lib/rdoc/rd/inline.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Inline keeps track of markup and labels to create proper links.
 
diff --git a/lib/rdoc/rd/inline_parser.rb b/lib/rdoc/rd/inline_parser.rb
index 98b503564da59f..240f68ba136c08 100644
--- a/lib/rdoc/rd/inline_parser.rb
+++ b/lib/rdoc/rd/inline_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # DO NOT MODIFY!!!!
 # This file is automatically generated by Racc 1.4.12
diff --git a/lib/rdoc/rdoc.rb b/lib/rdoc/rdoc.rb
index f4bb58e14bd70d..7c5d34e0894681 100644
--- a/lib/rdoc/rdoc.rb
+++ b/lib/rdoc/rdoc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc'
 
 require 'find'
diff --git a/lib/rdoc/require.rb b/lib/rdoc/require.rb
index a3d4bd18c07e45..f565ffad78c8bc 100644
--- a/lib/rdoc/require.rb
+++ b/lib/rdoc/require.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A file loaded by \#require
 
diff --git a/lib/rdoc/ri.rb b/lib/rdoc/ri.rb
index 8b35e0fa2fbcc0..388cb12c7046e9 100644
--- a/lib/rdoc/ri.rb
+++ b/lib/rdoc/ri.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc'
 
 ##
diff --git a/lib/rdoc/ri/driver.rb b/lib/rdoc/ri/driver.rb
index 39064c1384cad5..e571ae82ac38df 100644
--- a/lib/rdoc/ri/driver.rb
+++ b/lib/rdoc/ri/driver.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'abbrev'
 require 'optparse'
 
diff --git a/lib/rdoc/ri/formatter.rb b/lib/rdoc/ri/formatter.rb
index 84d37a9d31f1c0..d0c85dbe6bc20c 100644
--- a/lib/rdoc/ri/formatter.rb
+++ b/lib/rdoc/ri/formatter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # For RubyGems backwards compatibility
 
diff --git a/lib/rdoc/ri/paths.rb b/lib/rdoc/ri/paths.rb
index 970cb91461eaba..41529a3e0d5174 100644
--- a/lib/rdoc/ri/paths.rb
+++ b/lib/rdoc/ri/paths.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/ri'
 
 ##
diff --git a/lib/rdoc/ri/store.rb b/lib/rdoc/ri/store.rb
index 9fa9bbb03c298e..66e234f5211afd 100644
--- a/lib/rdoc/ri/store.rb
+++ b/lib/rdoc/ri/store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module RDoc::RI
 
   Store = RDoc::Store # :nodoc:
diff --git a/lib/rdoc/ri/task.rb b/lib/rdoc/ri/task.rb
index e545d4ac1e62ee..d45f0c664c3c16 100644
--- a/lib/rdoc/ri/task.rb
+++ b/lib/rdoc/ri/task.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 begin
   gem 'rdoc'
diff --git a/lib/rdoc/ruby_lex.rb b/lib/rdoc/ruby_lex.rb
index 91b90ab2cf5657..e772e660e0a8cc 100644
--- a/lib/rdoc/ruby_lex.rb
+++ b/lib/rdoc/ruby_lex.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 
 #--
 #   irb/ruby-lex.rb - ruby lexcal analyzer
diff --git a/lib/rdoc/ruby_token.rb b/lib/rdoc/ruby_token.rb
index f091e1a676a75a..d923e24b18fb74 100644
--- a/lib/rdoc/ruby_token.rb
+++ b/lib/rdoc/ruby_token.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 #   irb/ruby-token.rb - ruby tokens
 #   	$Release Version: 0.9.5$
diff --git a/lib/rdoc/rubygems_hook.rb b/lib/rdoc/rubygems_hook.rb
index c4eaddbd979d98..f6aeb845983715 100644
--- a/lib/rdoc/rubygems_hook.rb
+++ b/lib/rdoc/rubygems_hook.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/user_interaction'
 require 'fileutils'
diff --git a/lib/rdoc/servlet.rb b/lib/rdoc/servlet.rb
index 7ef04655e5f85d..952be255dbd12d 100644
--- a/lib/rdoc/servlet.rb
+++ b/lib/rdoc/servlet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc'
 require 'time'
 require 'json'
diff --git a/lib/rdoc/single_class.rb b/lib/rdoc/single_class.rb
index 358e1f38eb9d61..7affa027e1a733 100644
--- a/lib/rdoc/single_class.rb
+++ b/lib/rdoc/single_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A singleton class
 
diff --git a/lib/rdoc/stats.rb b/lib/rdoc/stats.rb
index 94fdd279c7546f..354e904b19a273 100644
--- a/lib/rdoc/stats.rb
+++ b/lib/rdoc/stats.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # RDoc statistics collector which prints a summary and report of a project's
 # documentation totals.
diff --git a/lib/rdoc/stats/normal.rb b/lib/rdoc/stats/normal.rb
index ef366a500e65f9..f32db48005a3f1 100644
--- a/lib/rdoc/stats/normal.rb
+++ b/lib/rdoc/stats/normal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'io/console/size'
 rescue LoadError
diff --git a/lib/rdoc/stats/quiet.rb b/lib/rdoc/stats/quiet.rb
index eed27b2a8878d5..561c272ef78150 100644
--- a/lib/rdoc/stats/quiet.rb
+++ b/lib/rdoc/stats/quiet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Stats printer that prints nothing
 
diff --git a/lib/rdoc/stats/verbose.rb b/lib/rdoc/stats/verbose.rb
index 430809ae07a0e5..e04edade52b513 100644
--- a/lib/rdoc/stats/verbose.rb
+++ b/lib/rdoc/stats/verbose.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Stats printer that prints everything documented, including the documented
 # status
diff --git a/lib/rdoc/store.rb b/lib/rdoc/store.rb
index fde6f0695b72a9..3f91f0582408ee 100644
--- a/lib/rdoc/store.rb
+++ b/lib/rdoc/store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'fileutils'
 
 ##
diff --git a/lib/rdoc/task.rb b/lib/rdoc/task.rb
index a83939090d259e..0577677054e246 100644
--- a/lib/rdoc/task.rb
+++ b/lib/rdoc/task.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright (c) 2003, 2004 Jim Weirich, 2009 Eric Hodel
 #
diff --git a/lib/rdoc/test_case.rb b/lib/rdoc/test_case.rb
index 4989516b7ab443..1d5469bc19e523 100644
--- a/lib/rdoc/test_case.rb
+++ b/lib/rdoc/test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 
 begin
diff --git a/lib/rdoc/text.rb b/lib/rdoc/text.rb
index 827767b830625c..71a35de101fe80 100644
--- a/lib/rdoc/text.rb
+++ b/lib/rdoc/text.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 ##
 # For RDoc::Text#to_html
diff --git a/lib/rdoc/token_stream.rb b/lib/rdoc/token_stream.rb
index b46b7da2f70e7f..b0035227fab675 100644
--- a/lib/rdoc/token_stream.rb
+++ b/lib/rdoc/token_stream.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A TokenStream is a list of tokens, gathered during the parse of some entity
 # (say a method). Entities populate these streams by being registered with the
diff --git a/lib/rdoc/tom_doc.rb b/lib/rdoc/tom_doc.rb
index 2b6224352572d2..d7608499385ccf 100644
--- a/lib/rdoc/tom_doc.rb
+++ b/lib/rdoc/tom_doc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # :markup: tomdoc
 
 # A parser for TomDoc based on TomDoc 1.0.0-rc1 (02adef9b5a)
diff --git a/lib/rdoc/top_level.rb b/lib/rdoc/top_level.rb
index 64d81d20c152e6..38be646ad06823 100644
--- a/lib/rdoc/top_level.rb
+++ b/lib/rdoc/top_level.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A TopLevel context is a representation of the contents of a single file
 
diff --git a/lib/rexml/attlistdecl.rb b/lib/rexml/attlistdecl.rb
index e2135d9e83d71e..dc1d2add0b8995 100644
--- a/lib/rexml/attlistdecl.rb
+++ b/lib/rexml/attlistdecl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #vim:ts=2 sw=2 noexpandtab:
 require 'rexml/child'
 require 'rexml/source'
diff --git a/lib/rexml/attribute.rb b/lib/rexml/attribute.rb
index ef9e54429434f5..e9917cf52d8796 100644
--- a/lib/rexml/attribute.rb
+++ b/lib/rexml/attribute.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/namespace"
 require 'rexml/text'
 
diff --git a/lib/rexml/cdata.rb b/lib/rexml/cdata.rb
index 73358edc289930..fe9b49b5f7c782 100644
--- a/lib/rexml/cdata.rb
+++ b/lib/rexml/cdata.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/text"
 
 module REXML
diff --git a/lib/rexml/child.rb b/lib/rexml/child.rb
index bf97d5f903e523..d23451e71ec843 100644
--- a/lib/rexml/child.rb
+++ b/lib/rexml/child.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/node"
 
 module REXML
diff --git a/lib/rexml/comment.rb b/lib/rexml/comment.rb
index 000b03dddd9096..746af772969acd 100644
--- a/lib/rexml/comment.rb
+++ b/lib/rexml/comment.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/child"
 
 module REXML
diff --git a/lib/rexml/doctype.rb b/lib/rexml/doctype.rb
index 0b3c533bb467b5..1eb1f5b4e18f8e 100644
--- a/lib/rexml/doctype.rb
+++ b/lib/rexml/doctype.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/parent"
 require "rexml/parseexception"
 require "rexml/namespace"
diff --git a/lib/rexml/document.rb b/lib/rexml/document.rb
index d7d24f473231f3..806bc499cde85a 100644
--- a/lib/rexml/document.rb
+++ b/lib/rexml/document.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/security"
 require "rexml/element"
 require "rexml/xmldecl"
diff --git a/lib/rexml/dtd/attlistdecl.rb b/lib/rexml/dtd/attlistdecl.rb
index 25955ee274960f..32847daadb2975 100644
--- a/lib/rexml/dtd/attlistdecl.rb
+++ b/lib/rexml/dtd/attlistdecl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/child"
 module REXML
   module DTD
diff --git a/lib/rexml/dtd/dtd.rb b/lib/rexml/dtd/dtd.rb
index 62317bac9e90e8..927d5d847b1a36 100644
--- a/lib/rexml/dtd/dtd.rb
+++ b/lib/rexml/dtd/dtd.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/dtd/elementdecl"
 require "rexml/dtd/entitydecl"
 require "rexml/comment"
diff --git a/lib/rexml/dtd/elementdecl.rb b/lib/rexml/dtd/elementdecl.rb
index f90b27d7614709..119fd41a8f6140 100644
--- a/lib/rexml/dtd/elementdecl.rb
+++ b/lib/rexml/dtd/elementdecl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/child"
 module REXML
   module DTD
diff --git a/lib/rexml/dtd/entitydecl.rb b/lib/rexml/dtd/entitydecl.rb
index a9286b2b90c219..45707e2f42d009 100644
--- a/lib/rexml/dtd/entitydecl.rb
+++ b/lib/rexml/dtd/entitydecl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/child"
 module REXML
   module DTD
diff --git a/lib/rexml/dtd/notationdecl.rb b/lib/rexml/dtd/notationdecl.rb
index 17d1b9ef293e9f..cfdf0b9b74a10e 100644
--- a/lib/rexml/dtd/notationdecl.rb
+++ b/lib/rexml/dtd/notationdecl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/child"
 module REXML
   module DTD
diff --git a/lib/rexml/element.rb b/lib/rexml/element.rb
index e459704d3cc15c..f725d5a2be53da 100644
--- a/lib/rexml/element.rb
+++ b/lib/rexml/element.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/parent"
 require "rexml/namespace"
 require "rexml/attribute"
diff --git a/lib/rexml/encoding.rb b/lib/rexml/encoding.rb
index 1c7e79a124a20e..da2d70d6c9d7be 100644
--- a/lib/rexml/encoding.rb
+++ b/lib/rexml/encoding.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 module REXML
   module Encoding
     # ID ---> Encoding name
diff --git a/lib/rexml/entity.rb b/lib/rexml/entity.rb
index 3a35ec6b9477a6..d9a72cc8fa147b 100644
--- a/lib/rexml/entity.rb
+++ b/lib/rexml/entity.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/child'
 require 'rexml/source'
 require 'rexml/xmltokens'
diff --git a/lib/rexml/formatters/default.rb b/lib/rexml/formatters/default.rb
index 574c821f964345..b84759d2ff5f51 100644
--- a/lib/rexml/formatters/default.rb
+++ b/lib/rexml/formatters/default.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   module Formatters
     class Default
diff --git a/lib/rexml/formatters/pretty.rb b/lib/rexml/formatters/pretty.rb
index e5ba561a584900..a80274bdad529a 100644
--- a/lib/rexml/formatters/pretty.rb
+++ b/lib/rexml/formatters/pretty.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/formatters/default'
 
 module REXML
diff --git a/lib/rexml/formatters/transitive.rb b/lib/rexml/formatters/transitive.rb
index 6cc690d9228a7f..81e67f3274ef3a 100644
--- a/lib/rexml/formatters/transitive.rb
+++ b/lib/rexml/formatters/transitive.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/formatters/pretty'
 
 module REXML
diff --git a/lib/rexml/functions.rb b/lib/rexml/functions.rb
index 2010be14e0179a..ee73b28881a871 100644
--- a/lib/rexml/functions.rb
+++ b/lib/rexml/functions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   # If you add a method, keep in mind two things:
   # (1) the first argument will always be a list of nodes from which to
diff --git a/lib/rexml/instruction.rb b/lib/rexml/instruction.rb
index f8b734a5b541e0..576939ca2b96d8 100644
--- a/lib/rexml/instruction.rb
+++ b/lib/rexml/instruction.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/child"
 require "rexml/source"
 
diff --git a/lib/rexml/light/node.rb b/lib/rexml/light/node.rb
index b33f78f7ceb2a0..d58119a3a44ebf 100644
--- a/lib/rexml/light/node.rb
+++ b/lib/rexml/light/node.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/xmltokens'
 
 # [ :element, parent, name, attributes, children* ]
diff --git a/lib/rexml/namespace.rb b/lib/rexml/namespace.rb
index aeb339ee8392a4..90ba7cc635bc8e 100644
--- a/lib/rexml/namespace.rb
+++ b/lib/rexml/namespace.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/xmltokens'
 
 module REXML
diff --git a/lib/rexml/node.rb b/lib/rexml/node.rb
index cab6e9fddb5dd9..c7a39367990e95 100644
--- a/lib/rexml/node.rb
+++ b/lib/rexml/node.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/parseexception"
 require "rexml/formatters/pretty"
 require "rexml/formatters/default"
diff --git a/lib/rexml/output.rb b/lib/rexml/output.rb
index 0c6cc7a7f845a6..96dfea570ed874 100644
--- a/lib/rexml/output.rb
+++ b/lib/rexml/output.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/encoding'
 
 module REXML
diff --git a/lib/rexml/parent.rb b/lib/rexml/parent.rb
index 2a07fcacbdaa66..3bd0a962555032 100644
--- a/lib/rexml/parent.rb
+++ b/lib/rexml/parent.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/child"
 
 module REXML
diff --git a/lib/rexml/parseexception.rb b/lib/rexml/parseexception.rb
index 0c4d55abdaa283..7b16cd1a411de4 100644
--- a/lib/rexml/parseexception.rb
+++ b/lib/rexml/parseexception.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   class ParseException < RuntimeError
     attr_accessor :source, :parser, :continued_exception
diff --git a/lib/rexml/parsers/baseparser.rb b/lib/rexml/parsers/baseparser.rb
index 6a08b8661d6d12..80eeb0fa79c1a6 100644
--- a/lib/rexml/parsers/baseparser.rb
+++ b/lib/rexml/parsers/baseparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/parseexception'
 require 'rexml/undefinednamespaceexception'
 require 'rexml/source'
diff --git a/lib/rexml/parsers/lightparser.rb b/lib/rexml/parsers/lightparser.rb
index 81041681c2e9d9..f0601ae51b1372 100644
--- a/lib/rexml/parsers/lightparser.rb
+++ b/lib/rexml/parsers/lightparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/parsers/streamparser'
 require 'rexml/parsers/baseparser'
 require 'rexml/light/node'
diff --git a/lib/rexml/parsers/pullparser.rb b/lib/rexml/parsers/pullparser.rb
index 68a4ff7eaed67c..8c4921755333c3 100644
--- a/lib/rexml/parsers/pullparser.rb
+++ b/lib/rexml/parsers/pullparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'forwardable'
 
 require 'rexml/parseexception'
diff --git a/lib/rexml/parsers/sax2parser.rb b/lib/rexml/parsers/sax2parser.rb
index a72c0a79714eff..1386f69c83fe56 100644
--- a/lib/rexml/parsers/sax2parser.rb
+++ b/lib/rexml/parsers/sax2parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/parsers/baseparser'
 require 'rexml/parseexception'
 require 'rexml/namespace'
diff --git a/lib/rexml/parsers/streamparser.rb b/lib/rexml/parsers/streamparser.rb
index 9ea65ed3d11398..b271e6743e1789 100644
--- a/lib/rexml/parsers/streamparser.rb
+++ b/lib/rexml/parsers/streamparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/parsers/baseparser"
 
 module REXML
diff --git a/lib/rexml/parsers/treeparser.rb b/lib/rexml/parsers/treeparser.rb
index 68edb777593ca0..fc0993c72a5aee 100644
--- a/lib/rexml/parsers/treeparser.rb
+++ b/lib/rexml/parsers/treeparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/validation/validationexception'
 require 'rexml/undefinednamespaceexception'
 
diff --git a/lib/rexml/parsers/ultralightparser.rb b/lib/rexml/parsers/ultralightparser.rb
index 4e2d7a81cf67d4..6571d119bd6930 100644
--- a/lib/rexml/parsers/ultralightparser.rb
+++ b/lib/rexml/parsers/ultralightparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/parsers/streamparser'
 require 'rexml/parsers/baseparser'
 
diff --git a/lib/rexml/parsers/xpathparser.rb b/lib/rexml/parsers/xpathparser.rb
index 57767fbcd1b3be..32b70bb7989889 100644
--- a/lib/rexml/parsers/xpathparser.rb
+++ b/lib/rexml/parsers/xpathparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/namespace'
 require 'rexml/xmltokens'
 
diff --git a/lib/rexml/quickpath.rb b/lib/rexml/quickpath.rb
index 9bec2158dd0cf2..f3ad29a93a08ed 100644
--- a/lib/rexml/quickpath.rb
+++ b/lib/rexml/quickpath.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/functions'
 require 'rexml/xmltokens'
 
diff --git a/lib/rexml/rexml.rb b/lib/rexml/rexml.rb
index f89951171a7e85..fbc0d339d88d31 100644
--- a/lib/rexml/rexml.rb
+++ b/lib/rexml/rexml.rb
@@ -1,4 +1,5 @@
 # -*- encoding: utf-8 -*-
+# frozen_string_literal: false
 # REXML is an XML toolkit for Ruby[http://www.ruby-lang.org], in Ruby.
 #
 # REXML is a _pure_ Ruby, XML 1.0 conforming,
diff --git a/lib/rexml/sax2listener.rb b/lib/rexml/sax2listener.rb
index 9f276eb4ed86f0..5afdc80890e7bd 100644
--- a/lib/rexml/sax2listener.rb
+++ b/lib/rexml/sax2listener.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   # A template for stream parser listeners.
   # Note that the declarations (attlistdecl, elementdecl, etc) are trivially
diff --git a/lib/rexml/security.rb b/lib/rexml/security.rb
index 593b652dc66b12..99b74607728b94 100644
--- a/lib/rexml/security.rb
+++ b/lib/rexml/security.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   module Security
     @@entity_expansion_limit = 10_000
diff --git a/lib/rexml/source.rb b/lib/rexml/source.rb
index 87f7232232b83e..af65cf4751a78d 100644
--- a/lib/rexml/source.rb
+++ b/lib/rexml/source.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'rexml/encoding'
 
 module REXML
diff --git a/lib/rexml/streamlistener.rb b/lib/rexml/streamlistener.rb
index 3a0528c10234ae..30c89451795485 100644
--- a/lib/rexml/streamlistener.rb
+++ b/lib/rexml/streamlistener.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   # A template for stream parser listeners.
   # Note that the declarations (attlistdecl, elementdecl, etc) are trivially
diff --git a/lib/rexml/syncenumerator.rb b/lib/rexml/syncenumerator.rb
index 11609bdf3daa9f..a9d2ad7f9c2b4c 100644
--- a/lib/rexml/syncenumerator.rb
+++ b/lib/rexml/syncenumerator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   class SyncEnumerator
     include Enumerable
diff --git a/lib/rexml/text.rb b/lib/rexml/text.rb
index d3242ee46db0ae..b132bab8f4601e 100644
--- a/lib/rexml/text.rb
+++ b/lib/rexml/text.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/security'
 require 'rexml/entity'
 require 'rexml/doctype'
diff --git a/lib/rexml/undefinednamespaceexception.rb b/lib/rexml/undefinednamespaceexception.rb
index 8ebfdfd0a9596f..e522ed57eaa3ad 100644
--- a/lib/rexml/undefinednamespaceexception.rb
+++ b/lib/rexml/undefinednamespaceexception.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/parseexception'
 module REXML
   class UndefinedNamespaceException < ParseException
diff --git a/lib/rexml/validation/relaxng.rb b/lib/rexml/validation/relaxng.rb
index 370efd5a980f6e..fb52438290d3f4 100644
--- a/lib/rexml/validation/relaxng.rb
+++ b/lib/rexml/validation/relaxng.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/validation/validation"
 require "rexml/parsers/baseparser"
 
diff --git a/lib/rexml/validation/validation.rb b/lib/rexml/validation/validation.rb
index bab7f225a54eec..f0c76f976ca928 100644
--- a/lib/rexml/validation/validation.rb
+++ b/lib/rexml/validation/validation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/validation/validationexception'
 
 module REXML
diff --git a/lib/rexml/validation/validationexception.rb b/lib/rexml/validation/validationexception.rb
index 4723d9e4d3c654..78cd63fd04662c 100644
--- a/lib/rexml/validation/validationexception.rb
+++ b/lib/rexml/validation/validationexception.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   module Validation
     class ValidationException < RuntimeError
diff --git a/lib/rexml/xmldecl.rb b/lib/rexml/xmldecl.rb
index 465e6abeb76e9b..a37e9f3ddc6420 100644
--- a/lib/rexml/xmldecl.rb
+++ b/lib/rexml/xmldecl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/encoding'
 require 'rexml/source'
 
diff --git a/lib/rexml/xmltokens.rb b/lib/rexml/xmltokens.rb
index 4d4dd27f2da372..392b47b1d33cf5 100644
--- a/lib/rexml/xmltokens.rb
+++ b/lib/rexml/xmltokens.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module REXML
   # Defines a number of tokens used for parsing XML.  Not for general
   # consumption.
diff --git a/lib/rexml/xpath.rb b/lib/rexml/xpath.rb
index 0f99808defe42f..f1cb99baea05cc 100644
--- a/lib/rexml/xpath.rb
+++ b/lib/rexml/xpath.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/functions'
 require 'rexml/xpath_parser'
 
diff --git a/lib/rexml/xpath_parser.rb b/lib/rexml/xpath_parser.rb
index ef49a32fbaff83..edd11277353ff7 100644
--- a/lib/rexml/xpath_parser.rb
+++ b/lib/rexml/xpath_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/namespace'
 require 'rexml/xmltokens'
 require 'rexml/attribute'
diff --git a/lib/rinda/rinda.rb b/lib/rinda/rinda.rb
index d9cd3782a0f925..36c3503aa8a447 100644
--- a/lib/rinda/rinda.rb
+++ b/lib/rinda/rinda.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'thread'
 
diff --git a/lib/rinda/ring.rb b/lib/rinda/ring.rb
index fe33420494f505..9ec8a2fb2fec3e 100644
--- a/lib/rinda/ring.rb
+++ b/lib/rinda/ring.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Note: Rinda::Ring API is unstable.
 #
diff --git a/lib/rinda/tuplespace.rb b/lib/rinda/tuplespace.rb
index 14cae9ebed5e97..e29bd63126a5d9 100644
--- a/lib/rinda/tuplespace.rb
+++ b/lib/rinda/tuplespace.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'monitor'
 require 'thread'
 require 'drb/drb'
diff --git a/lib/rss.rb b/lib/rss.rb
index fd7364645bf122..1c7d72b9f7ed63 100644
--- a/lib/rss.rb
+++ b/lib/rss.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # = RSS reading and writing
 #
diff --git a/lib/rss/0.9.rb b/lib/rss/0.9.rb
index 77b2de131c8557..d852a6a85e98ee 100644
--- a/lib/rss/0.9.rb
+++ b/lib/rss/0.9.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/parser"
 
 module RSS
diff --git a/lib/rss/1.0.rb b/lib/rss/1.0.rb
index a2d88d459e0ec1..fb63937c5e1505 100644
--- a/lib/rss/1.0.rb
+++ b/lib/rss/1.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/parser"
 
 module RSS
diff --git a/lib/rss/2.0.rb b/lib/rss/2.0.rb
index 5c0caecd73e3f5..13f9ade918a2f4 100644
--- a/lib/rss/2.0.rb
+++ b/lib/rss/2.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/0.9"
 
 module RSS
diff --git a/lib/rss/atom.rb b/lib/rss/atom.rb
index d3524231ff088a..a232e358be002e 100644
--- a/lib/rss/atom.rb
+++ b/lib/rss/atom.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/parser'
 
 module RSS
diff --git a/lib/rss/content.rb b/lib/rss/content.rb
index 5a2120c0671cdd..d35311075a2cfa 100644
--- a/lib/rss/content.rb
+++ b/lib/rss/content.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/rss"
 
 module RSS
diff --git a/lib/rss/content/1.0.rb b/lib/rss/content/1.0.rb
index e5dc85793036d2..1367dfe092448d 100644
--- a/lib/rss/content/1.0.rb
+++ b/lib/rss/content/1.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/1.0'
 
 module RSS
diff --git a/lib/rss/content/2.0.rb b/lib/rss/content/2.0.rb
index 8491a999377380..3b468248ace866 100644
--- a/lib/rss/content/2.0.rb
+++ b/lib/rss/content/2.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/2.0"
 
 module RSS
diff --git a/lib/rss/converter.rb b/lib/rss/converter.rb
index 3e79eba4fb3a2f..b92e35a051d172 100644
--- a/lib/rss/converter.rb
+++ b/lib/rss/converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/utils"
 
 module RSS
diff --git a/lib/rss/dublincore.rb b/lib/rss/dublincore.rb
index 58424141cdc84e..8d1a5519472182 100644
--- a/lib/rss/dublincore.rb
+++ b/lib/rss/dublincore.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/rss"
 
 module RSS
diff --git a/lib/rss/dublincore/1.0.rb b/lib/rss/dublincore/1.0.rb
index efe2f5dad48170..1d96fab9b91c71 100644
--- a/lib/rss/dublincore/1.0.rb
+++ b/lib/rss/dublincore/1.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/1.0"
 
 module RSS
diff --git a/lib/rss/dublincore/2.0.rb b/lib/rss/dublincore/2.0.rb
index a79c1e84a4d065..e3011fef6a3203 100644
--- a/lib/rss/dublincore/2.0.rb
+++ b/lib/rss/dublincore/2.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/2.0"
 
 module RSS
diff --git a/lib/rss/dublincore/atom.rb b/lib/rss/dublincore/atom.rb
index 8db9066bb8ac3e..0b8b11e440b4e3 100644
--- a/lib/rss/dublincore/atom.rb
+++ b/lib/rss/dublincore/atom.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/atom"
 
 module RSS
diff --git a/lib/rss/image.rb b/lib/rss/image.rb
index b0619141bbd40f..6b86ec0e5b60ca 100644
--- a/lib/rss/image.rb
+++ b/lib/rss/image.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/1.0'
 require 'rss/dublincore'
 
diff --git a/lib/rss/itunes.rb b/lib/rss/itunes.rb
index e6de5c1ca281f9..827970c20970e5 100644
--- a/lib/rss/itunes.rb
+++ b/lib/rss/itunes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/2.0'
 
 module RSS
diff --git a/lib/rss/maker.rb b/lib/rss/maker.rb
index 824b2b2dcd1896..33d285f6afb50d 100644
--- a/lib/rss/maker.rb
+++ b/lib/rss/maker.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/rss"
 
 module RSS
diff --git a/lib/rss/maker/0.9.rb b/lib/rss/maker/0.9.rb
index c398343ec4320a..622a4c30b4c3b5 100644
--- a/lib/rss/maker/0.9.rb
+++ b/lib/rss/maker/0.9.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/0.9"
 
 require "rss/maker/base"
diff --git a/lib/rss/maker/1.0.rb b/lib/rss/maker/1.0.rb
index 1b9f7c3b796f03..3aee77e913b1d2 100644
--- a/lib/rss/maker/1.0.rb
+++ b/lib/rss/maker/1.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/1.0"
 
 require "rss/maker/base"
diff --git a/lib/rss/maker/2.0.rb b/lib/rss/maker/2.0.rb
index 15b1349c2a6ecb..1f77a014d12c86 100644
--- a/lib/rss/maker/2.0.rb
+++ b/lib/rss/maker/2.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/2.0"
 
 require "rss/maker/0.9"
diff --git a/lib/rss/maker/atom.rb b/lib/rss/maker/atom.rb
index fd3198cd9e6b00..e0cd7623c86ecb 100644
--- a/lib/rss/maker/atom.rb
+++ b/lib/rss/maker/atom.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/atom"
 
 require "rss/maker/base"
diff --git a/lib/rss/maker/base.rb b/lib/rss/maker/base.rb
index 0f2fc11103e736..bc4ca841419fb8 100644
--- a/lib/rss/maker/base.rb
+++ b/lib/rss/maker/base.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'forwardable'
 
 require 'rss/rss'
diff --git a/lib/rss/maker/content.rb b/lib/rss/maker/content.rb
index 46c4911f737f49..3559a45ad02c75 100644
--- a/lib/rss/maker/content.rb
+++ b/lib/rss/maker/content.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/content'
 require 'rss/maker/1.0'
 require 'rss/maker/2.0'
diff --git a/lib/rss/maker/dublincore.rb b/lib/rss/maker/dublincore.rb
index 717b074fae8ad2..988209c045b53a 100644
--- a/lib/rss/maker/dublincore.rb
+++ b/lib/rss/maker/dublincore.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/dublincore'
 require 'rss/maker/1.0'
 
diff --git a/lib/rss/maker/entry.rb b/lib/rss/maker/entry.rb
index f8f5469f2cb0c0..f806cbcaae85bb 100644
--- a/lib/rss/maker/entry.rb
+++ b/lib/rss/maker/entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/maker/atom"
 require "rss/maker/feed"
 
diff --git a/lib/rss/maker/feed.rb b/lib/rss/maker/feed.rb
index 0129218b0c5a47..fdef7ad6430bfc 100644
--- a/lib/rss/maker/feed.rb
+++ b/lib/rss/maker/feed.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/maker/atom"
 
 module RSS
diff --git a/lib/rss/maker/image.rb b/lib/rss/maker/image.rb
index 06084b4af469c7..1957ba86891511 100644
--- a/lib/rss/maker/image.rb
+++ b/lib/rss/maker/image.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/image'
 require 'rss/maker/1.0'
 require 'rss/maker/dublincore'
diff --git a/lib/rss/maker/itunes.rb b/lib/rss/maker/itunes.rb
index 8b7420da3ce847..cc1051ae0c22cc 100644
--- a/lib/rss/maker/itunes.rb
+++ b/lib/rss/maker/itunes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/itunes'
 require 'rss/maker/2.0'
 
diff --git a/lib/rss/maker/slash.rb b/lib/rss/maker/slash.rb
index 27adef383290b6..3bd82d305702d9 100644
--- a/lib/rss/maker/slash.rb
+++ b/lib/rss/maker/slash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/slash'
 require 'rss/maker/1.0'
 
diff --git a/lib/rss/maker/syndication.rb b/lib/rss/maker/syndication.rb
index b81230457ce366..840b70229ab06d 100644
--- a/lib/rss/maker/syndication.rb
+++ b/lib/rss/maker/syndication.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/syndication'
 require 'rss/maker/1.0'
 
diff --git a/lib/rss/maker/taxonomy.rb b/lib/rss/maker/taxonomy.rb
index 13ae9aa8052e75..76a2d1600d488c 100644
--- a/lib/rss/maker/taxonomy.rb
+++ b/lib/rss/maker/taxonomy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/taxonomy'
 require 'rss/maker/1.0'
 require 'rss/maker/dublincore'
diff --git a/lib/rss/maker/trackback.rb b/lib/rss/maker/trackback.rb
index 00f001cb8550b8..f97691c608eaf9 100644
--- a/lib/rss/maker/trackback.rb
+++ b/lib/rss/maker/trackback.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/trackback'
 require 'rss/maker/1.0'
 require 'rss/maker/2.0'
diff --git a/lib/rss/parser.rb b/lib/rss/parser.rb
index 1b6e4e9596519b..a9842e6d40877a 100644
--- a/lib/rss/parser.rb
+++ b/lib/rss/parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "forwardable"
 require "open-uri"
 
diff --git a/lib/rss/rexmlparser.rb b/lib/rss/rexmlparser.rb
index a5a2a2edbe46fa..ef0595e447f2ae 100644
--- a/lib/rss/rexmlparser.rb
+++ b/lib/rss/rexmlparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/document"
 require "rexml/streamlistener"
 
diff --git a/lib/rss/rss.rb b/lib/rss/rss.rb
index dbea3b53444571..1bb0f6e8265889 100644
--- a/lib/rss/rss.rb
+++ b/lib/rss/rss.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "time"
 
 class Time
diff --git a/lib/rss/slash.rb b/lib/rss/slash.rb
index 65c61142e13f69..0055fc9f885e35 100644
--- a/lib/rss/slash.rb
+++ b/lib/rss/slash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rss/1.0'
 
 module RSS
diff --git a/lib/rss/syndication.rb b/lib/rss/syndication.rb
index c0bd5294f466db..8f9620f9f3f35b 100644
--- a/lib/rss/syndication.rb
+++ b/lib/rss/syndication.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/1.0"
 
 module RSS
diff --git a/lib/rss/taxonomy.rb b/lib/rss/taxonomy.rb
index b7fbe6b0de046d..b7ea219e8cbbfb 100644
--- a/lib/rss/taxonomy.rb
+++ b/lib/rss/taxonomy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/1.0"
 require "rss/dublincore"
 
diff --git a/lib/rss/trackback.rb b/lib/rss/trackback.rb
index 577bf0cef7c514..1a3c3849b57154 100644
--- a/lib/rss/trackback.rb
+++ b/lib/rss/trackback.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # This file contains the implementation of trackbacks. It is entirely internal
 # and not useful to outside developers.
 require 'rss/1.0'
diff --git a/lib/rss/utils.rb b/lib/rss/utils.rb
index b420e6b24cd1f6..ce7dbf1b02b025 100644
--- a/lib/rss/utils.rb
+++ b/lib/rss/utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module RSS
 
   ##
diff --git a/lib/rss/xml-stylesheet.rb b/lib/rss/xml-stylesheet.rb
index 96ee95050ec605..be9cfaaf64bc4f 100644
--- a/lib/rss/xml-stylesheet.rb
+++ b/lib/rss/xml-stylesheet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/utils"
 
 module RSS
diff --git a/lib/rss/xml.rb b/lib/rss/xml.rb
index 1ae878b7721336..cda8668044f8fe 100644
--- a/lib/rss/xml.rb
+++ b/lib/rss/xml.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rss/utils"
 
 module RSS
diff --git a/lib/rss/xmlparser.rb b/lib/rss/xmlparser.rb
index 46df94a3203d6c..cb2dd2afdd90a3 100644
--- a/lib/rss/xmlparser.rb
+++ b/lib/rss/xmlparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require "xml/parser"
 rescue LoadError
diff --git a/lib/rss/xmlscanner.rb b/lib/rss/xmlscanner.rb
index 1cdf81c0c3bf63..6e3b13d2f57f50 100644
--- a/lib/rss/xmlscanner.rb
+++ b/lib/rss/xmlscanner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'xmlscan/scanner'
 require 'stringio'
 
diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index f0861b3533c146..fdcc2aa4d39d1b 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # -*- ruby -*-
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
diff --git a/lib/rubygems/available_set.rb b/lib/rubygems/available_set.rb
index dae254b385781c..da43cdf3fbe9b9 100644
--- a/lib/rubygems/available_set.rb
+++ b/lib/rubygems/available_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Gem::AvailableSet
 
   include Enumerable
diff --git a/lib/rubygems/basic_specification.rb b/lib/rubygems/basic_specification.rb
index 53beb434023ac5..db962c6dcd5f58 100644
--- a/lib/rubygems/basic_specification.rb
+++ b/lib/rubygems/basic_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # BasicSpecification is an abstract class which implements some common code
 # used by both Specification and StubSpecification.
diff --git a/lib/rubygems/command.rb b/lib/rubygems/command.rb
index 0c6abec56ced02..28af3d090c8107 100644
--- a/lib/rubygems/command.rb
+++ b/lib/rubygems/command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/command_manager.rb b/lib/rubygems/command_manager.rb
index 53d18c29cc3ab0..95e846e34077c0 100644
--- a/lib/rubygems/command_manager.rb
+++ b/lib/rubygems/command_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/commands/build_command.rb b/lib/rubygems/commands/build_command.rb
index d975429fe85fc3..facc5226af4376 100644
--- a/lib/rubygems/commands/build_command.rb
+++ b/lib/rubygems/commands/build_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/package'
 
diff --git a/lib/rubygems/commands/cert_command.rb b/lib/rubygems/commands/cert_command.rb
index a920e7fcc3652b..073c6bd1957005 100644
--- a/lib/rubygems/commands/cert_command.rb
+++ b/lib/rubygems/commands/cert_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/security'
 begin
diff --git a/lib/rubygems/commands/check_command.rb b/lib/rubygems/commands/check_command.rb
index 8893b9c3b2a59f..9d2b0869516d5f 100644
--- a/lib/rubygems/commands/check_command.rb
+++ b/lib/rubygems/commands/check_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/version_option'
 require 'rubygems/validator'
diff --git a/lib/rubygems/commands/cleanup_command.rb b/lib/rubygems/commands/cleanup_command.rb
index 69975640fe3276..a0bb3d576a93ca 100644
--- a/lib/rubygems/commands/cleanup_command.rb
+++ b/lib/rubygems/commands/cleanup_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/dependency_list'
 require 'rubygems/uninstaller'
diff --git a/lib/rubygems/commands/contents_command.rb b/lib/rubygems/commands/contents_command.rb
index 4b944f18be2312..de756939c0bf9d 100644
--- a/lib/rubygems/commands/contents_command.rb
+++ b/lib/rubygems/commands/contents_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'English'
 require 'rubygems/command'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/dependency_command.rb b/lib/rubygems/commands/dependency_command.rb
index 9d4b3e0f504877..b9e33a94e03755 100644
--- a/lib/rubygems/commands/dependency_command.rb
+++ b/lib/rubygems/commands/dependency_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/environment_command.rb b/lib/rubygems/commands/environment_command.rb
index 79dd710bdff037..47b62f03afb3cd 100644
--- a/lib/rubygems/commands/environment_command.rb
+++ b/lib/rubygems/commands/environment_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 
 class Gem::Commands::EnvironmentCommand < Gem::Command
diff --git a/lib/rubygems/commands/fetch_command.rb b/lib/rubygems/commands/fetch_command.rb
index c57ab0089ae5ab..3aecdc3b080aea 100644
--- a/lib/rubygems/commands/fetch_command.rb
+++ b/lib/rubygems/commands/fetch_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/generate_index_command.rb b/lib/rubygems/commands/generate_index_command.rb
index ca6f694bc56d7d..c0fadba64f3c15 100644
--- a/lib/rubygems/commands/generate_index_command.rb
+++ b/lib/rubygems/commands/generate_index_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/indexer'
 
diff --git a/lib/rubygems/commands/help_command.rb b/lib/rubygems/commands/help_command.rb
index c4078364677819..4c176f372e2b2a 100644
--- a/lib/rubygems/commands/help_command.rb
+++ b/lib/rubygems/commands/help_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 
 class Gem::Commands::HelpCommand < Gem::Command
diff --git a/lib/rubygems/commands/install_command.rb b/lib/rubygems/commands/install_command.rb
index 7e3a953d192100..6e243df441e006 100644
--- a/lib/rubygems/commands/install_command.rb
+++ b/lib/rubygems/commands/install_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/install_update_options'
 require 'rubygems/dependency_installer'
diff --git a/lib/rubygems/commands/list_command.rb b/lib/rubygems/commands/list_command.rb
index 6aa00d30b8d212..1f85cd3fcd892a 100644
--- a/lib/rubygems/commands/list_command.rb
+++ b/lib/rubygems/commands/list_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/commands/query_command'
 
diff --git a/lib/rubygems/commands/lock_command.rb b/lib/rubygems/commands/lock_command.rb
index 6b4b25a28129ca..5a56e91933181f 100644
--- a/lib/rubygems/commands/lock_command.rb
+++ b/lib/rubygems/commands/lock_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 
 class Gem::Commands::LockCommand < Gem::Command
diff --git a/lib/rubygems/commands/mirror_command.rb b/lib/rubygems/commands/mirror_command.rb
index 24fb668d5410d6..3816876a92a7ba 100644
--- a/lib/rubygems/commands/mirror_command.rb
+++ b/lib/rubygems/commands/mirror_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 
 unless defined? Gem::Commands::MirrorCommand
diff --git a/lib/rubygems/commands/open_command.rb b/lib/rubygems/commands/open_command.rb
index 254a74275e6d08..63bff16db0f7f4 100644
--- a/lib/rubygems/commands/open_command.rb
+++ b/lib/rubygems/commands/open_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'English'
 require 'rubygems/command'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/outdated_command.rb b/lib/rubygems/commands/outdated_command.rb
index 7159dbb984c4d4..f7cfc08f70ae02 100644
--- a/lib/rubygems/commands/outdated_command.rb
+++ b/lib/rubygems/commands/outdated_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/spec_fetcher'
diff --git a/lib/rubygems/commands/owner_command.rb b/lib/rubygems/commands/owner_command.rb
index 322bf6590a1e43..b002ff18d4ccc5 100644
--- a/lib/rubygems/commands/owner_command.rb
+++ b/lib/rubygems/commands/owner_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/gemcutter_utilities'
diff --git a/lib/rubygems/commands/pristine_command.rb b/lib/rubygems/commands/pristine_command.rb
index 5a36b1235822a8..991272ae8552ca 100644
--- a/lib/rubygems/commands/pristine_command.rb
+++ b/lib/rubygems/commands/pristine_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/package'
 require 'rubygems/installer'
diff --git a/lib/rubygems/commands/push_command.rb b/lib/rubygems/commands/push_command.rb
index 6899b489ad74cb..a8e0819e82529e 100644
--- a/lib/rubygems/commands/push_command.rb
+++ b/lib/rubygems/commands/push_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/gemcutter_utilities'
diff --git a/lib/rubygems/commands/query_command.rb b/lib/rubygems/commands/query_command.rb
index 0d28711de80f1d..4782eb98efa493 100644
--- a/lib/rubygems/commands/query_command.rb
+++ b/lib/rubygems/commands/query_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/spec_fetcher'
diff --git a/lib/rubygems/commands/rdoc_command.rb b/lib/rubygems/commands/rdoc_command.rb
index 86597f99a65e29..72aa9720177df9 100644
--- a/lib/rubygems/commands/rdoc_command.rb
+++ b/lib/rubygems/commands/rdoc_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/version_option'
 require 'rubygems/rdoc'
diff --git a/lib/rubygems/commands/search_command.rb b/lib/rubygems/commands/search_command.rb
index a1e2c1a00e3dfd..06cc997d4cd852 100644
--- a/lib/rubygems/commands/search_command.rb
+++ b/lib/rubygems/commands/search_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/commands/query_command'
 
diff --git a/lib/rubygems/commands/server_command.rb b/lib/rubygems/commands/server_command.rb
index 4796ce2ad6ea1e..f41bda40daaf7a 100644
--- a/lib/rubygems/commands/server_command.rb
+++ b/lib/rubygems/commands/server_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/server'
 
diff --git a/lib/rubygems/commands/setup_command.rb b/lib/rubygems/commands/setup_command.rb
index 66173967802c81..d3ef9ef94e1fba 100644
--- a/lib/rubygems/commands/setup_command.rb
+++ b/lib/rubygems/commands/setup_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 
 ##
diff --git a/lib/rubygems/commands/sources_command.rb b/lib/rubygems/commands/sources_command.rb
index 56d7845c54f12c..0ff5e075f5a665 100644
--- a/lib/rubygems/commands/sources_command.rb
+++ b/lib/rubygems/commands/sources_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/remote_fetcher'
 require 'rubygems/spec_fetcher'
diff --git a/lib/rubygems/commands/specification_command.rb b/lib/rubygems/commands/specification_command.rb
index 3bc02a9c14bcd7..4e291c6ab11dc5 100644
--- a/lib/rubygems/commands/specification_command.rb
+++ b/lib/rubygems/commands/specification_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/stale_command.rb b/lib/rubygems/commands/stale_command.rb
index 0ef0755960ead9..6930c1cfde5e36 100644
--- a/lib/rubygems/commands/stale_command.rb
+++ b/lib/rubygems/commands/stale_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 
 class Gem::Commands::StaleCommand < Gem::Command
diff --git a/lib/rubygems/commands/uninstall_command.rb b/lib/rubygems/commands/uninstall_command.rb
index 9285e57b773a20..52d4450bfbe50f 100644
--- a/lib/rubygems/commands/uninstall_command.rb
+++ b/lib/rubygems/commands/uninstall_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/version_option'
 require 'rubygems/uninstaller'
diff --git a/lib/rubygems/commands/unpack_command.rb b/lib/rubygems/commands/unpack_command.rb
index 5a05ad0a81e8be..08eaf0131499d8 100644
--- a/lib/rubygems/commands/unpack_command.rb
+++ b/lib/rubygems/commands/unpack_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/installer'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/commands/update_command.rb b/lib/rubygems/commands/update_command.rb
index c758ce8a9da822..8d76a8ce8ea818 100644
--- a/lib/rubygems/commands/update_command.rb
+++ b/lib/rubygems/commands/update_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/command_manager'
 require 'rubygems/dependency_installer'
diff --git a/lib/rubygems/commands/which_command.rb b/lib/rubygems/commands/which_command.rb
index 96eeb862883e17..c01dc18ee012ad 100644
--- a/lib/rubygems/commands/which_command.rb
+++ b/lib/rubygems/commands/which_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 
 class Gem::Commands::WhichCommand < Gem::Command
diff --git a/lib/rubygems/commands/yank_command.rb b/lib/rubygems/commands/yank_command.rb
index c05ee66283769c..ec99bd7df682a9 100644
--- a/lib/rubygems/commands/yank_command.rb
+++ b/lib/rubygems/commands/yank_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 require 'rubygems/local_remote_options'
 require 'rubygems/version_option'
diff --git a/lib/rubygems/compatibility.rb b/lib/rubygems/compatibility.rb
index 6a00a199f95091..d09ddb6bf8b4b0 100644
--- a/lib/rubygems/compatibility.rb
+++ b/lib/rubygems/compatibility.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # :stopdoc:
 
 #--
diff --git a/lib/rubygems/config_file.rb b/lib/rubygems/config_file.rb
index f93917cbd43800..30f26db8c98fad 100644
--- a/lib/rubygems/config_file.rb
+++ b/lib/rubygems/config_file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/core_ext/kernel_gem.rb b/lib/rubygems/core_ext/kernel_gem.rb
index 61e77fe3c5c289..07376784e6855d 100644
--- a/lib/rubygems/core_ext/kernel_gem.rb
+++ b/lib/rubygems/core_ext/kernel_gem.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # RubyGems adds the #gem method to allow activation of specific gem versions
 # and overrides the #require method on Kernel to make gems appear as if they
diff --git a/lib/rubygems/core_ext/kernel_require.rb b/lib/rubygems/core_ext/kernel_require.rb
index f9b67ea5a65d49..196db5b6eefe27 100755
--- a/lib/rubygems/core_ext/kernel_require.rb
+++ b/lib/rubygems/core_ext/kernel_require.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/defaults.rb b/lib/rubygems/defaults.rb
index 55ca080c96f22a..c1d45c19e6e519 100644
--- a/lib/rubygems/defaults.rb
+++ b/lib/rubygems/defaults.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem
   DEFAULT_HOST = "https://rubygems.org"
 
diff --git a/lib/rubygems/dependency.rb b/lib/rubygems/dependency.rb
index da990fa13921e4..c0ab87d965c686 100644
--- a/lib/rubygems/dependency.rb
+++ b/lib/rubygems/dependency.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The Dependency class holds a Gem name and a Gem::Requirement.
 
diff --git a/lib/rubygems/dependency_installer.rb b/lib/rubygems/dependency_installer.rb
index 9741554360d917..954e2bf9841d3a 100644
--- a/lib/rubygems/dependency_installer.rb
+++ b/lib/rubygems/dependency_installer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/dependency_list'
 require 'rubygems/package'
diff --git a/lib/rubygems/dependency_list.rb b/lib/rubygems/dependency_list.rb
index c034bb65896683..8e00dc94c80fb0 100644
--- a/lib/rubygems/dependency_list.rb
+++ b/lib/rubygems/dependency_list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/deprecate.rb b/lib/rubygems/deprecate.rb
index e19360da13a81f..54ab02830c2620 100644
--- a/lib/rubygems/deprecate.rb
+++ b/lib/rubygems/deprecate.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Provides a single method +deprecate+ to be used to declare when
 # something is going away.
diff --git a/lib/rubygems/doctor.rb b/lib/rubygems/doctor.rb
index 3c71fd5aa4448b..15f05f63fadfa0 100644
--- a/lib/rubygems/doctor.rb
+++ b/lib/rubygems/doctor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/user_interaction'
 
diff --git a/lib/rubygems/errors.rb b/lib/rubygems/errors.rb
index 9defb9ee9bd88d..b22cd077066444 100644
--- a/lib/rubygems/errors.rb
+++ b/lib/rubygems/errors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # This file contains all the various exceptions and other errors that are used
 # inside of RubyGems.
diff --git a/lib/rubygems/exceptions.rb b/lib/rubygems/exceptions.rb
index 2a9875cd24b9a4..0c741a2d016184 100644
--- a/lib/rubygems/exceptions.rb
+++ b/lib/rubygems/exceptions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # TODO: the documentation in here is terrible.
 #
 # Each exception needs a brief description and the scenarios where it is
diff --git a/lib/rubygems/ext.rb b/lib/rubygems/ext.rb
index 5af6bbf39efa5a..4640b668f0245e 100644
--- a/lib/rubygems/ext.rb
+++ b/lib/rubygems/ext.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/build_error.rb b/lib/rubygems/ext/build_error.rb
index bfe85ffc113124..2098026b05582b 100644
--- a/lib/rubygems/ext/build_error.rb
+++ b/lib/rubygems/ext/build_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Raised when there is an error while building extensions.
 
diff --git a/lib/rubygems/ext/builder.rb b/lib/rubygems/ext/builder.rb
index abcc09ce5742e0..d79b3a59011b7f 100644
--- a/lib/rubygems/ext/builder.rb
+++ b/lib/rubygems/ext/builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/cmake_builder.rb b/lib/rubygems/ext/cmake_builder.rb
index 24531bc75c7ebb..7bf431c37eac71 100644
--- a/lib/rubygems/ext/cmake_builder.rb
+++ b/lib/rubygems/ext/cmake_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command'
 
 class Gem::Ext::CmakeBuilder < Gem::Ext::Builder
diff --git a/lib/rubygems/ext/configure_builder.rb b/lib/rubygems/ext/configure_builder.rb
index f66e39387a2214..b732cada577bd8 100644
--- a/lib/rubygems/ext/configure_builder.rb
+++ b/lib/rubygems/ext/configure_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/ext_conf_builder.rb b/lib/rubygems/ext/ext_conf_builder.rb
index f5c4c8ce8486f6..2b50b08dc963f4 100644
--- a/lib/rubygems/ext/ext_conf_builder.rb
+++ b/lib/rubygems/ext/ext_conf_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/ext/rake_builder.rb b/lib/rubygems/ext/rake_builder.rb
index d5ebf597aee5fa..279117675a2bf5 100644
--- a/lib/rubygems/ext/rake_builder.rb
+++ b/lib/rubygems/ext/rake_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/gem_runner.rb b/lib/rubygems/gem_runner.rb
index 7a3fd6b1168142..2bf8ac68bf3289 100644
--- a/lib/rubygems/gem_runner.rb
+++ b/lib/rubygems/gem_runner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/gemcutter_utilities.rb b/lib/rubygems/gemcutter_utilities.rb
index 4ecf7376e09d0f..98e78fe341541f 100644
--- a/lib/rubygems/gemcutter_utilities.rb
+++ b/lib/rubygems/gemcutter_utilities.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/remote_fetcher'
 
 ##
diff --git a/lib/rubygems/indexer.rb b/lib/rubygems/indexer.rb
index 23279f40ecda47..21ccf0dfbbd046 100644
--- a/lib/rubygems/indexer.rb
+++ b/lib/rubygems/indexer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/package'
 require 'time'
diff --git a/lib/rubygems/install_default_message.rb b/lib/rubygems/install_default_message.rb
index 458ba3da9602a3..d20a6c71a31de9 100644
--- a/lib/rubygems/install_default_message.rb
+++ b/lib/rubygems/install_default_message.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/user_interaction'
 
diff --git a/lib/rubygems/install_message.rb b/lib/rubygems/install_message.rb
index c1979c154941b2..da68b192b111dd 100644
--- a/lib/rubygems/install_message.rb
+++ b/lib/rubygems/install_message.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/user_interaction'
 
diff --git a/lib/rubygems/install_update_options.rb b/lib/rubygems/install_update_options.rb
index a503b7fca42f2c..0466583e429c86 100644
--- a/lib/rubygems/install_update_options.rb
+++ b/lib/rubygems/install_update_options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/installer.rb b/lib/rubygems/installer.rb
index 69590c39d885ce..7b4979d7ca2761 100644
--- a/lib/rubygems/installer.rb
+++ b/lib/rubygems/installer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/installer_test_case.rb b/lib/rubygems/installer_test_case.rb
index f4aa773114e044..7a1b0aa5f0dc7e 100644
--- a/lib/rubygems/installer_test_case.rb
+++ b/lib/rubygems/installer_test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/installer'
 
diff --git a/lib/rubygems/local_remote_options.rb b/lib/rubygems/local_remote_options.rb
index db23d9f9748f44..8d9e209771a876 100644
--- a/lib/rubygems/local_remote_options.rb
+++ b/lib/rubygems/local_remote_options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/mock_gem_ui.rb b/lib/rubygems/mock_gem_ui.rb
index 76a9389676ef12..32e154c8b3f95b 100644
--- a/lib/rubygems/mock_gem_ui.rb
+++ b/lib/rubygems/mock_gem_ui.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'stringio'
 require 'rubygems/user_interaction'
 
diff --git a/lib/rubygems/name_tuple.rb b/lib/rubygems/name_tuple.rb
index 60323db408823d..1dc7f741124c70 100644
--- a/lib/rubygems/name_tuple.rb
+++ b/lib/rubygems/name_tuple.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 #
 # Represents a gem of name +name+ at +version+ of +platform+. These
diff --git a/lib/rubygems/package.rb b/lib/rubygems/package.rb
index 64beae55503cdc..6b87475c785042 100644
--- a/lib/rubygems/package.rb
+++ b/lib/rubygems/package.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package/digest_io.rb b/lib/rubygems/package/digest_io.rb
index f8bde0f557f439..47f76ec10d809c 100644
--- a/lib/rubygems/package/digest_io.rb
+++ b/lib/rubygems/package/digest_io.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # IO wrapper that creates digests of contents written to the IO it wraps.
 
diff --git a/lib/rubygems/package/file_source.rb b/lib/rubygems/package/file_source.rb
index 85316f62e7da82..4c2a7b9a4e86b2 100644
--- a/lib/rubygems/package/file_source.rb
+++ b/lib/rubygems/package/file_source.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The primary source of gems is a file on disk, including all usages
 # internal to rubygems.
diff --git a/lib/rubygems/package/io_source.rb b/lib/rubygems/package/io_source.rb
index f89593dd2d490b..16a6e4be8b90aa 100644
--- a/lib/rubygems/package/io_source.rb
+++ b/lib/rubygems/package/io_source.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Supports reading and writing gems from/to a generic IO object.  This is
 # useful for other applications built on top of rubygems, such as
diff --git a/lib/rubygems/package/old.rb b/lib/rubygems/package/old.rb
index bcf60a00c9e09a..1f1f33b856a8b6 100644
--- a/lib/rubygems/package/old.rb
+++ b/lib/rubygems/package/old.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/package/source.rb b/lib/rubygems/package/source.rb
index 1f18d479da0adf..3dcce02a672776 100644
--- a/lib/rubygems/package/source.rb
+++ b/lib/rubygems/package/source.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Gem::Package::Source # :nodoc:
 end
 
diff --git a/lib/rubygems/package/tar_header.rb b/lib/rubygems/package/tar_header.rb
index f9ab13aca77447..71529ee978563b 100644
--- a/lib/rubygems/package/tar_header.rb
+++ b/lib/rubygems/package/tar_header.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package/tar_reader.rb b/lib/rubygems/package/tar_reader.rb
index e257fdd846aa66..a1ea81cac481e2 100644
--- a/lib/rubygems/package/tar_reader.rb
+++ b/lib/rubygems/package/tar_reader.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package/tar_reader/entry.rb b/lib/rubygems/package/tar_reader/entry.rb
index 1d917a81ac03cb..59d167ee8e1e59 100644
--- a/lib/rubygems/package/tar_reader/entry.rb
+++ b/lib/rubygems/package/tar_reader/entry.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #++
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package/tar_test_case.rb b/lib/rubygems/package/tar_test_case.rb
index b2d6f4ea772b49..3e494e55949323 100644
--- a/lib/rubygems/package/tar_test_case.rb
+++ b/lib/rubygems/package/tar_test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/package'
 
diff --git a/lib/rubygems/package/tar_writer.rb b/lib/rubygems/package/tar_writer.rb
index fff02e92355e1b..6f1aab47a166ef 100644
--- a/lib/rubygems/package/tar_writer.rb
+++ b/lib/rubygems/package/tar_writer.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #--
 # Copyright (C) 2004 Mauricio Julio Fernández Pradier
 # See LICENSE.txt for additional licensing information.
diff --git a/lib/rubygems/package_task.rb b/lib/rubygems/package_task.rb
index 09384cc0e72288..0c525ad517009e 100644
--- a/lib/rubygems/package_task.rb
+++ b/lib/rubygems/package_task.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # Copyright (c) 2003, 2004 Jim Weirich, 2009 Eric Hodel
 #
 # Permission is hereby granted, free of charge, to any person obtaining
diff --git a/lib/rubygems/path_support.rb b/lib/rubygems/path_support.rb
index e68654c428377e..0ec29f8b600c85 100644
--- a/lib/rubygems/path_support.rb
+++ b/lib/rubygems/path_support.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 #
 # Gem::PathSupport facilitates the GEM_HOME and GEM_PATH environment settings
diff --git a/lib/rubygems/platform.rb b/lib/rubygems/platform.rb
index 487d245a01b488..cdc52cc9b33373 100644
--- a/lib/rubygems/platform.rb
+++ b/lib/rubygems/platform.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rubygems/deprecate"
 
 ##
diff --git a/lib/rubygems/psych_additions.rb b/lib/rubygems/psych_additions.rb
index 08fc04c90dee82..487b2699036322 100644
--- a/lib/rubygems/psych_additions.rb
+++ b/lib/rubygems/psych_additions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # This exists just to satisfy bugs in marshal'd gemspecs that
 # contain a reference to YAML::PrivateType. We prune these out
 # in Specification._load, but if we don't have the constant, Marshal
diff --git a/lib/rubygems/psych_tree.rb b/lib/rubygems/psych_tree.rb
index e3f1d1a08afdcb..a5d306d769e24c 100644
--- a/lib/rubygems/psych_tree.rb
+++ b/lib/rubygems/psych_tree.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem
   if defined? ::Psych::Visitors
     class NoAliasYAMLTree < Psych::Visitors::YAMLTree
diff --git a/lib/rubygems/rdoc.rb b/lib/rubygems/rdoc.rb
index 75913463060723..e9402ede768efd 100644
--- a/lib/rubygems/rdoc.rb
+++ b/lib/rubygems/rdoc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/user_interaction'
 require 'fileutils'
diff --git a/lib/rubygems/remote_fetcher.rb b/lib/rubygems/remote_fetcher.rb
index 8c7ee78f840443..db1eed89d4608e 100644
--- a/lib/rubygems/remote_fetcher.rb
+++ b/lib/rubygems/remote_fetcher.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/request'
 require 'rubygems/uri_formatter'
diff --git a/lib/rubygems/request.rb b/lib/rubygems/request.rb
index b1d041d8eada41..3dfbc3d89c9398 100644
--- a/lib/rubygems/request.rb
+++ b/lib/rubygems/request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'net/http'
 require 'thread'
 require 'time'
diff --git a/lib/rubygems/request/connection_pools.rb b/lib/rubygems/request/connection_pools.rb
index 271b32b2b119d6..d22e3572575625 100644
--- a/lib/rubygems/request/connection_pools.rb
+++ b/lib/rubygems/request/connection_pools.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'thread'
 
 class Gem::Request::ConnectionPools # :nodoc:
diff --git a/lib/rubygems/request/http_pool.rb b/lib/rubygems/request/http_pool.rb
index c9a1858b98a23e..ba3ab095bd98fa 100644
--- a/lib/rubygems/request/http_pool.rb
+++ b/lib/rubygems/request/http_pool.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A connection "pool" that only manages one connection for now.  Provides
 # thread safe `checkout` and `checkin` methods.  The pool consists of one
diff --git a/lib/rubygems/request/https_pool.rb b/lib/rubygems/request/https_pool.rb
index 2e3da0a44ef440..3ab91faf61ab7c 100644
--- a/lib/rubygems/request/https_pool.rb
+++ b/lib/rubygems/request/https_pool.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Gem::Request::HTTPSPool < Gem::Request::HTTPPool # :nodoc:
   private
 
diff --git a/lib/rubygems/request_set.rb b/lib/rubygems/request_set.rb
index 12806836aabf3e..b760a05d9bf35e 100644
--- a/lib/rubygems/request_set.rb
+++ b/lib/rubygems/request_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'tsort'
 
 ##
diff --git a/lib/rubygems/request_set/gem_dependency_api.rb b/lib/rubygems/request_set/gem_dependency_api.rb
index 73813c9ac7dae4..4927e5db6a3122 100644
--- a/lib/rubygems/request_set/gem_dependency_api.rb
+++ b/lib/rubygems/request_set/gem_dependency_api.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A semi-compatible DSL for the Bundler Gemfile and Isolate gem dependencies
 # files.
diff --git a/lib/rubygems/request_set/lockfile.rb b/lib/rubygems/request_set/lockfile.rb
index b79a37724855a8..e9a706e83b1da2 100644
--- a/lib/rubygems/request_set/lockfile.rb
+++ b/lib/rubygems/request_set/lockfile.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Parses a gem.deps.rb.lock file and constructs a LockSet containing the
 # dependencies found inside.  If the lock file is missing no LockSet is
diff --git a/lib/rubygems/request_set/lockfile/parser.rb b/lib/rubygems/request_set/lockfile/parser.rb
index f43f6457fd2795..18aaadf3bb08b2 100644
--- a/lib/rubygems/request_set/lockfile/parser.rb
+++ b/lib/rubygems/request_set/lockfile/parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Gem::RequestSet::Lockfile::Parser
   ###
   # Parses lockfiles
diff --git a/lib/rubygems/request_set/lockfile/tokenizer.rb b/lib/rubygems/request_set/lockfile/tokenizer.rb
index 422b03c03f3b4c..d68645d235f724 100644
--- a/lib/rubygems/request_set/lockfile/tokenizer.rb
+++ b/lib/rubygems/request_set/lockfile/tokenizer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'strscan'
 require 'rubygems/request_set/lockfile/parser'
 
diff --git a/lib/rubygems/requirement.rb b/lib/rubygems/requirement.rb
index de169265735136..a33f67dafb2dae 100644
--- a/lib/rubygems/requirement.rb
+++ b/lib/rubygems/requirement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rubygems/version"
 require "rubygems/deprecate"
 
diff --git a/lib/rubygems/resolver.rb b/lib/rubygems/resolver.rb
index dcd33ce10d4bfa..92dcab8e42cf85 100644
--- a/lib/rubygems/resolver.rb
+++ b/lib/rubygems/resolver.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/dependency'
 require 'rubygems/exceptions'
 require 'rubygems/util'
diff --git a/lib/rubygems/resolver/activation_request.rb b/lib/rubygems/resolver/activation_request.rb
index 03dd8d083bffc0..2dd540cda03f8a 100644
--- a/lib/rubygems/resolver/activation_request.rb
+++ b/lib/rubygems/resolver/activation_request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Specifies a Specification object that should be activated.  Also contains a
 # dependency that was used to introduce this activation.
diff --git a/lib/rubygems/resolver/api_set.rb b/lib/rubygems/resolver/api_set.rb
index 17d602f9877276..611c74ad10ea35 100644
--- a/lib/rubygems/resolver/api_set.rb
+++ b/lib/rubygems/resolver/api_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The global rubygems pool, available via the rubygems.org API.
 # Returns instances of APISpecification.
diff --git a/lib/rubygems/resolver/api_specification.rb b/lib/rubygems/resolver/api_specification.rb
index 4960e66934d982..e7ba38d6143c64 100644
--- a/lib/rubygems/resolver/api_specification.rb
+++ b/lib/rubygems/resolver/api_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Represents a specification retrieved via the rubygems.org API.
 #
diff --git a/lib/rubygems/resolver/best_set.rb b/lib/rubygems/resolver/best_set.rb
index 7e2d7e2647e2cb..c3c756c5e34df0 100644
--- a/lib/rubygems/resolver/best_set.rb
+++ b/lib/rubygems/resolver/best_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The BestSet chooses the best available method to query a remote index.
 #
diff --git a/lib/rubygems/resolver/composed_set.rb b/lib/rubygems/resolver/composed_set.rb
index 5b08f128ed997c..66d927be2a2215 100644
--- a/lib/rubygems/resolver/composed_set.rb
+++ b/lib/rubygems/resolver/composed_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A ComposedSet allows multiple sets to be queried like a single set.
 #
diff --git a/lib/rubygems/resolver/conflict.rb b/lib/rubygems/resolver/conflict.rb
index 0b6c704d6ab66c..101923eb747639 100644
--- a/lib/rubygems/resolver/conflict.rb
+++ b/lib/rubygems/resolver/conflict.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Used internally to indicate that a dependency conflicted
 # with a spec that would be activated.
diff --git a/lib/rubygems/resolver/current_set.rb b/lib/rubygems/resolver/current_set.rb
index 4e8d34026b109c..f8cec599ded88d 100644
--- a/lib/rubygems/resolver/current_set.rb
+++ b/lib/rubygems/resolver/current_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A set which represents the installed gems. Respects
 # all the normal settings that control where to look
diff --git a/lib/rubygems/resolver/dependency_request.rb b/lib/rubygems/resolver/dependency_request.rb
index 6c6ea8f4da0ad8..ded554a85a81bf 100644
--- a/lib/rubygems/resolver/dependency_request.rb
+++ b/lib/rubygems/resolver/dependency_request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Used Internally. Wraps a Dependency object to also track which spec
 # contained the Dependency.
diff --git a/lib/rubygems/resolver/git_set.rb b/lib/rubygems/resolver/git_set.rb
index 5f1b368ac1fd88..2b5aae64c69644 100644
--- a/lib/rubygems/resolver/git_set.rb
+++ b/lib/rubygems/resolver/git_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A GitSet represents gems that are sourced from git repositories.
 #
diff --git a/lib/rubygems/resolver/git_specification.rb b/lib/rubygems/resolver/git_specification.rb
index dcfb2ad8550176..507f346812cc8c 100644
--- a/lib/rubygems/resolver/git_specification.rb
+++ b/lib/rubygems/resolver/git_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A GitSpecification represents a gem that is sourced from a git repository
 # and is being loaded through a gem dependencies file through the +git:+
diff --git a/lib/rubygems/resolver/index_set.rb b/lib/rubygems/resolver/index_set.rb
index 7c56c2bf9990ac..e7cd989095af31 100644
--- a/lib/rubygems/resolver/index_set.rb
+++ b/lib/rubygems/resolver/index_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The global rubygems pool represented via the traditional
 # source index.
diff --git a/lib/rubygems/resolver/index_specification.rb b/lib/rubygems/resolver/index_specification.rb
index 56fecb5753e0df..632a8a2d891bbe 100644
--- a/lib/rubygems/resolver/index_specification.rb
+++ b/lib/rubygems/resolver/index_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Represents a possible Specification object returned from IndexSet.  Used to
 # delay needed to download full Specification objects when only the +name+
diff --git a/lib/rubygems/resolver/installed_specification.rb b/lib/rubygems/resolver/installed_specification.rb
index 2a2b89a6c295d6..06da6af3dbeafb 100644
--- a/lib/rubygems/resolver/installed_specification.rb
+++ b/lib/rubygems/resolver/installed_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # An InstalledSpecification represents a gem that is already installed
 # locally.
diff --git a/lib/rubygems/resolver/installer_set.rb b/lib/rubygems/resolver/installer_set.rb
index a68ff09dbdfd59..d840b7171146f8 100644
--- a/lib/rubygems/resolver/installer_set.rb
+++ b/lib/rubygems/resolver/installer_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A set of gems for installation sourced from remote sources and local .gem
 # files
diff --git a/lib/rubygems/resolver/local_specification.rb b/lib/rubygems/resolver/local_specification.rb
index 20a283f0badab5..76192e4c0b4990 100644
--- a/lib/rubygems/resolver/local_specification.rb
+++ b/lib/rubygems/resolver/local_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A LocalSpecification comes from a .gem file on the local filesystem.
 
diff --git a/lib/rubygems/resolver/lock_set.rb b/lib/rubygems/resolver/lock_set.rb
index 4ede5971fbd08c..fb581a1508875d 100644
--- a/lib/rubygems/resolver/lock_set.rb
+++ b/lib/rubygems/resolver/lock_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A set of gems from a gem dependencies lockfile.
 
diff --git a/lib/rubygems/resolver/lock_specification.rb b/lib/rubygems/resolver/lock_specification.rb
index 00131714695742..02268787524608 100644
--- a/lib/rubygems/resolver/lock_specification.rb
+++ b/lib/rubygems/resolver/lock_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The LockSpecification comes from a lockfile (Gem::RequestSet::Lockfile).
 #
diff --git a/lib/rubygems/resolver/molinillo.rb b/lib/rubygems/resolver/molinillo.rb
index 24ac0f9b2d28f9..019536dc9b3961 100644
--- a/lib/rubygems/resolver/molinillo.rb
+++ b/lib/rubygems/resolver/molinillo.rb
@@ -1 +1,2 @@
+# frozen_string_literal: false
 require 'rubygems/resolver/molinillo/lib/molinillo'
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo.rb b/lib/rubygems/resolver/molinillo/lib/molinillo.rb
index 47b451832127ee..34dc7787dc0dac 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/resolver/molinillo/lib/molinillo/gem_metadata'
 require 'rubygems/resolver/molinillo/lib/molinillo/errors'
 require 'rubygems/resolver/molinillo/lib/molinillo/resolver'
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
index 9780200e6fcd57..c3a1d5a2ef7f9a 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'set'
 require 'tsort'
 
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/errors.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/errors.rb
index cc9f636ed582d6..074ee9dd7dfa74 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/errors.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/errors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem::Resolver::Molinillo
   # An error that occurred during the resolution process
   class ResolverError < StandardError; end
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/gem_metadata.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/gem_metadata.rb
index 73a0daa528ad2b..8140c57a58ec80 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/gem_metadata.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/gem_metadata.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem::Resolver::Molinillo
   VERSION = '0.4.0'
 end
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider.rb
index 848392b2154e2d..10c655ac32ddef 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/modules/specification_provider.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem::Resolver::Molinillo
   # Provides information about specifcations and dependencies to the resolver,
   # allowing the {Resolver} class to remain generic while still providing power
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/modules/ui.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/modules/ui.rb
index 18f53639509d32..100b694ebc8a96 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/modules/ui.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/modules/ui.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem::Resolver::Molinillo
   # Conveys information about the resolution process to a user.
   module UI
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb
index cc572b411a38d8..5a0eb368494193 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem::Resolver::Molinillo
   class Resolver
     # A specific resolution from a given {Resolver}
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb
index b22caf44da697a..a92b3273ab005b 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/resolver/molinillo/lib/molinillo/dependency_graph'
 
 module Gem::Resolver::Molinillo
diff --git a/lib/rubygems/resolver/molinillo/lib/molinillo/state.rb b/lib/rubygems/resolver/molinillo/lib/molinillo/state.rb
index f0317185ab3be1..7bc9d9892771a9 100644
--- a/lib/rubygems/resolver/molinillo/lib/molinillo/state.rb
+++ b/lib/rubygems/resolver/molinillo/lib/molinillo/state.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem::Resolver::Molinillo
   # A state that a {Resolution} can be in
   # @attr [String] name
diff --git a/lib/rubygems/resolver/requirement_list.rb b/lib/rubygems/resolver/requirement_list.rb
index a6bfaab307e45b..32f2ac5a9918f5 100644
--- a/lib/rubygems/resolver/requirement_list.rb
+++ b/lib/rubygems/resolver/requirement_list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The RequirementList is used to hold the requirements being considered
 # while resolving a set of gems.
diff --git a/lib/rubygems/resolver/set.rb b/lib/rubygems/resolver/set.rb
index b26dc45c7b7fe9..e2253abf3ab496 100644
--- a/lib/rubygems/resolver/set.rb
+++ b/lib/rubygems/resolver/set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Resolver sets are used to look up specifications (and their
 # dependencies) used in resolution.  This set is abstract.
diff --git a/lib/rubygems/resolver/spec_specification.rb b/lib/rubygems/resolver/spec_specification.rb
index 1350e8a7ab88a6..00a0533bb5814d 100644
--- a/lib/rubygems/resolver/spec_specification.rb
+++ b/lib/rubygems/resolver/spec_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The Resolver::SpecSpecification contains common functionality for
 # Resolver specifications that are backed by a Gem::Specification.
diff --git a/lib/rubygems/resolver/specification.rb b/lib/rubygems/resolver/specification.rb
index 9b597f19168965..5833320660fa50 100644
--- a/lib/rubygems/resolver/specification.rb
+++ b/lib/rubygems/resolver/specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A Resolver::Specification contains a subset of the information
 # contained in a Gem::Specification.  Only the information necessary for
diff --git a/lib/rubygems/resolver/stats.rb b/lib/rubygems/resolver/stats.rb
index c31e5be9626445..4de766f2e1d8b5 100644
--- a/lib/rubygems/resolver/stats.rb
+++ b/lib/rubygems/resolver/stats.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Gem::Resolver::Stats
   def initialize
     @max_depth = 0
diff --git a/lib/rubygems/resolver/vendor_set.rb b/lib/rubygems/resolver/vendor_set.rb
index 614bd05382c2cb..a006220ffe6ad8 100644
--- a/lib/rubygems/resolver/vendor_set.rb
+++ b/lib/rubygems/resolver/vendor_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A VendorSet represents gems that have been unpacked into a specific
 # directory that contains a gemspec.
diff --git a/lib/rubygems/resolver/vendor_specification.rb b/lib/rubygems/resolver/vendor_specification.rb
index a99b5f3cc19081..ecf8e74def63f9 100644
--- a/lib/rubygems/resolver/vendor_specification.rb
+++ b/lib/rubygems/resolver/vendor_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A VendorSpecification represents a gem that has been unpacked into a project
 # and is being loaded through a gem dependencies file through the +path:+
diff --git a/lib/rubygems/security.rb b/lib/rubygems/security.rb
index 8c5fb7d9f2e146..d44ebec9f5a1db 100644
--- a/lib/rubygems/security.rb
+++ b/lib/rubygems/security.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/security/policies.rb b/lib/rubygems/security/policies.rb
index a976ecaf590069..05c6bbdb2a0941 100644
--- a/lib/rubygems/security/policies.rb
+++ b/lib/rubygems/security/policies.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem::Security
 
   ##
diff --git a/lib/rubygems/security/policy.rb b/lib/rubygems/security/policy.rb
index b9bcb175255480..0e13497b9d1b43 100644
--- a/lib/rubygems/security/policy.rb
+++ b/lib/rubygems/security/policy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/user_interaction'
 
 ##
diff --git a/lib/rubygems/security/signer.rb b/lib/rubygems/security/signer.rb
index fbee240f298ec6..a6d0161edcbdfb 100644
--- a/lib/rubygems/security/signer.rb
+++ b/lib/rubygems/security/signer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Basic OpenSSL-based package signing class.
 
diff --git a/lib/rubygems/security/trust_dir.rb b/lib/rubygems/security/trust_dir.rb
index 76ef89af7f772b..a032debf6e88a9 100644
--- a/lib/rubygems/security/trust_dir.rb
+++ b/lib/rubygems/security/trust_dir.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The TrustDir manages the trusted certificates for gem signature
 # verification.
diff --git a/lib/rubygems/server.rb b/lib/rubygems/server.rb
index 7655be22cef674..d83a928571f9d2 100644
--- a/lib/rubygems/server.rb
+++ b/lib/rubygems/server.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'webrick'
 require 'zlib'
 require 'erb'
diff --git a/lib/rubygems/source.rb b/lib/rubygems/source.rb
index e5995f005f9a19..7a58a441d2b2eb 100644
--- a/lib/rubygems/source.rb
+++ b/lib/rubygems/source.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'uri'
 require 'fileutils'
 
diff --git a/lib/rubygems/source/git.rb b/lib/rubygems/source/git.rb
index 35c2270a744d39..7096ebe617491c 100644
--- a/lib/rubygems/source/git.rb
+++ b/lib/rubygems/source/git.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'digest'
 require 'rubygems/util'
 
diff --git a/lib/rubygems/source/installed.rb b/lib/rubygems/source/installed.rb
index bd05c75af17f2f..3327010768d603 100644
--- a/lib/rubygems/source/installed.rb
+++ b/lib/rubygems/source/installed.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Represents an installed gem.  This is used for dependency resolution.
 
diff --git a/lib/rubygems/source/local.rb b/lib/rubygems/source/local.rb
index 8057921163e89f..a320ff1c66ac0d 100644
--- a/lib/rubygems/source/local.rb
+++ b/lib/rubygems/source/local.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The local source finds gems in the current directory for fulfilling
 # dependencies.
diff --git a/lib/rubygems/source/lock.rb b/lib/rubygems/source/lock.rb
index 2ba7702bdadec6..98fef5a4d1fcb1 100644
--- a/lib/rubygems/source/lock.rb
+++ b/lib/rubygems/source/lock.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A Lock source wraps an installed gem's source and sorts before other sources
 # during dependency resolution.  This allows RubyGems to prefer gems from
diff --git a/lib/rubygems/source/specific_file.rb b/lib/rubygems/source/specific_file.rb
index 250a83920349f3..790e4240335ee4 100644
--- a/lib/rubygems/source/specific_file.rb
+++ b/lib/rubygems/source/specific_file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # A source representing a single .gem file.  This is used for installation of
 # local gems.
diff --git a/lib/rubygems/source/vendor.rb b/lib/rubygems/source/vendor.rb
index 2d936231c167c8..057d54ebeac401 100644
--- a/lib/rubygems/source/vendor.rb
+++ b/lib/rubygems/source/vendor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # This represents a vendored source that is similar to an installed gem.
 
diff --git a/lib/rubygems/source_list.rb b/lib/rubygems/source_list.rb
index e01f11cc1e2146..add82f232742ad 100644
--- a/lib/rubygems/source_list.rb
+++ b/lib/rubygems/source_list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/source'
 
 ##
diff --git a/lib/rubygems/source_local.rb b/lib/rubygems/source_local.rb
index 0808f4694abfc1..d56b697718899e 100644
--- a/lib/rubygems/source_local.rb
+++ b/lib/rubygems/source_local.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/source'
 require 'rubygems/source_local'
 
diff --git a/lib/rubygems/source_specific_file.rb b/lib/rubygems/source_specific_file.rb
index f785c2667ca0e5..2ae57927812e33 100644
--- a/lib/rubygems/source_specific_file.rb
+++ b/lib/rubygems/source_specific_file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/source/specific_file'
 
 # TODO warn upon require, this file is deprecated.
diff --git a/lib/rubygems/spec_fetcher.rb b/lib/rubygems/spec_fetcher.rb
index 4967c4a40b93e3..dbeecad2436010 100644
--- a/lib/rubygems/spec_fetcher.rb
+++ b/lib/rubygems/spec_fetcher.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/remote_fetcher'
 require 'rubygems/user_interaction'
 require 'rubygems/errors'
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index 50c27aa272cc72..ddba38da841f56 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/stub_specification.rb b/lib/rubygems/stub_specification.rb
index 482a75bd48ed43..98ec7ce0702c3b 100644
--- a/lib/rubygems/stub_specification.rb
+++ b/lib/rubygems/stub_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # Gem::StubSpecification reads the stub: line from the gemspec.  This prevents
 # us having to eval the entire gemspec in order to find out certain
diff --git a/lib/rubygems/syck_hack.rb b/lib/rubygems/syck_hack.rb
index 92179abb53f707..0f49793ea1aceb 100644
--- a/lib/rubygems/syck_hack.rb
+++ b/lib/rubygems/syck_hack.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # :stopdoc:
 
 # Hack to handle syck's DefaultKey bug
diff --git a/lib/rubygems/test_case.rb b/lib/rubygems/test_case.rb
index 0e0bdfbe3e12f0..3ffc608a1cb476 100644
--- a/lib/rubygems/test_case.rb
+++ b/lib/rubygems/test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # TODO: $SAFE = 1
 
 begin
diff --git a/lib/rubygems/test_utilities.rb b/lib/rubygems/test_utilities.rb
index 6789f6efc5e78c..bb633eb3cc4e56 100644
--- a/lib/rubygems/test_utilities.rb
+++ b/lib/rubygems/test_utilities.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'tempfile'
 require 'rubygems'
 require 'rubygems/remote_fetcher'
diff --git a/lib/rubygems/text.rb b/lib/rubygems/text.rb
index 4c033cf00e77e4..470874621b6b98 100644
--- a/lib/rubygems/text.rb
+++ b/lib/rubygems/text.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 
 ##
diff --git a/lib/rubygems/uninstaller.rb b/lib/rubygems/uninstaller.rb
index bb3e204c8d962c..b54eeba585eb06 100644
--- a/lib/rubygems/uninstaller.rb
+++ b/lib/rubygems/uninstaller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/uri_formatter.rb b/lib/rubygems/uri_formatter.rb
index 68aacc6369cbc3..bf0fc287a4e85a 100644
--- a/lib/rubygems/uri_formatter.rb
+++ b/lib/rubygems/uri_formatter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'cgi'
 require 'uri'
 
diff --git a/lib/rubygems/user_interaction.rb b/lib/rubygems/user_interaction.rb
index 78d37906c9a86c..69eb26df5a1c5c 100644
--- a/lib/rubygems/user_interaction.rb
+++ b/lib/rubygems/user_interaction.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/util.rb b/lib/rubygems/util.rb
index 9bfe13f815df3d..76d8ad4bc1dc8e 100644
--- a/lib/rubygems/util.rb
+++ b/lib/rubygems/util.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # This module contains various utility methods as module methods.
 
diff --git a/lib/rubygems/util/licenses.rb b/lib/rubygems/util/licenses.rb
index a15b556c3eed88..08ebd925f736ac 100644
--- a/lib/rubygems/util/licenses.rb
+++ b/lib/rubygems/util/licenses.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Gem::Licenses
   NONSTANDARD = 'Nonstandard'.freeze
 
diff --git a/lib/rubygems/util/list.rb b/lib/rubygems/util/list.rb
index 6fa767646c605b..83dc8497c4bdb7 100644
--- a/lib/rubygems/util/list.rb
+++ b/lib/rubygems/util/list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Gem
   class List
     include Enumerable
diff --git a/lib/rubygems/validator.rb b/lib/rubygems/validator.rb
index 6992af16baf62d..8a13e9911bbda5 100644
--- a/lib/rubygems/validator.rb
+++ b/lib/rubygems/validator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/rubygems/version.rb b/lib/rubygems/version.rb
index 16e20c524644c7..8e37baa3484fb9 100644
--- a/lib/rubygems/version.rb
+++ b/lib/rubygems/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The Version class processes string versions into comparable
 # values. A version string should normally be a series of numbers
diff --git a/lib/rubygems/version_option.rb b/lib/rubygems/version_option.rb
index a0755d50206571..a31cb14db48c4b 100644
--- a/lib/rubygems/version_option.rb
+++ b/lib/rubygems/version_option.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/lib/scanf.rb b/lib/scanf.rb
index 6ba6847616e4a1..a98c3595735ad5 100644
--- a/lib/scanf.rb
+++ b/lib/scanf.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # scanf for Ruby
 #
 #--
diff --git a/lib/shell.rb b/lib/shell.rb
index db2d6879083ba7..bf389795b789c1 100644
--- a/lib/shell.rb
+++ b/lib/shell.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   shell.rb -
 #       $Release Version: 0.7 $
diff --git a/lib/shell/builtin-command.rb b/lib/shell/builtin-command.rb
index 80a0ce5534b87f..c76fa81ee134a2 100644
--- a/lib/shell/builtin-command.rb
+++ b/lib/shell/builtin-command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   shell/builtin-command.rb -
 #       $Release Version: 0.7 $
diff --git a/lib/shell/command-processor.rb b/lib/shell/command-processor.rb
index 13bc50c3fe043f..2239ca98f63d88 100644
--- a/lib/shell/command-processor.rb
+++ b/lib/shell/command-processor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   shell/command-controller.rb -
 #       $Release Version: 0.7 $
diff --git a/lib/shell/error.rb b/lib/shell/error.rb
index 2701338b5a0c3b..677c424baf6832 100644
--- a/lib/shell/error.rb
+++ b/lib/shell/error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   shell/error.rb -
 #       $Release Version: 0.7 $
diff --git a/lib/shell/filter.rb b/lib/shell/filter.rb
index 9fae07d23ece64..c1f4b28a45e48c 100644
--- a/lib/shell/filter.rb
+++ b/lib/shell/filter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   shell/filter.rb -
 #       $Release Version: 0.7 $
diff --git a/lib/shell/process-controller.rb b/lib/shell/process-controller.rb
index d0cad0ec056d47..a100727aa6376d 100644
--- a/lib/shell/process-controller.rb
+++ b/lib/shell/process-controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   shell/process-controller.rb -
 #       $Release Version: 0.7 $
diff --git a/lib/shell/system-command.rb b/lib/shell/system-command.rb
index 1fe37333d64514..2a8ffd6ed928ba 100644
--- a/lib/shell/system-command.rb
+++ b/lib/shell/system-command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   shell/system-command.rb -
 #       $Release Version: 0.7 $
diff --git a/lib/shell/version.rb b/lib/shell/version.rb
index 2568627e2b0b45..bb4e7dfb8ed4f7 100644
--- a/lib/shell/version.rb
+++ b/lib/shell/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   version.rb - shell version definition file
 #       $Release Version: 0.7$
diff --git a/lib/shellwords.rb b/lib/shellwords.rb
index 0030f0784fbca1..76aedbc1797f3b 100644
--- a/lib/shellwords.rb
+++ b/lib/shellwords.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # frozen-string-literal: true
 ##
 # == Manipulates strings like the UNIX Bourne shell
diff --git a/lib/singleton.rb b/lib/singleton.rb
index be1f7ff6cac26f..2ee9b5b3b55f2f 100644
--- a/lib/singleton.rb
+++ b/lib/singleton.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'thread'
 
 # The Singleton module implements the Singleton pattern.
diff --git a/lib/sync.rb b/lib/sync.rb
index 09542d59f94522..ad6caf074357c2 100644
--- a/lib/sync.rb
+++ b/lib/sync.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   sync.rb - 2 phase lock with counter
 #       $Release Version: 1.0$
diff --git a/lib/tempfile.rb b/lib/tempfile.rb
index 77f3e4ede36b4b..13d9585a3b1656 100644
--- a/lib/tempfile.rb
+++ b/lib/tempfile.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # tempfile - manipulates temporary files
 #
diff --git a/lib/thwait.rb b/lib/thwait.rb
index d9750a406b213f..db7e6b1ce5c4a4 100644
--- a/lib/thwait.rb
+++ b/lib/thwait.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   thwait.rb - thread synchronization class
 #       $Release Version: 0.9 $
diff --git a/lib/timeout.rb b/lib/timeout.rb
index 63a629923d17f1..79d28b6c5e763c 100644
--- a/lib/timeout.rb
+++ b/lib/timeout.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # Timeout long-running blocks
 #
 # == Synopsis
diff --git a/lib/tracer.rb b/lib/tracer.rb
index 1d6b019bcf8c85..fd45f003c89909 100644
--- a/lib/tracer.rb
+++ b/lib/tracer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # $Release Version: 0.3$
 # $Revision: 1.12 $
diff --git a/lib/ubygems.rb b/lib/ubygems.rb
index fec880f73b152a..3d1798fe98435f 100644
--- a/lib/ubygems.rb
+++ b/lib/ubygems.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # This file allows for the running of rubygems with a nice
 # command line look-and-feel: ruby -rubygems foo.rb
 #--
diff --git a/lib/un.rb b/lib/un.rb
index 1f336a4442dc8a..9c1ce624a58d6f 100644
--- a/lib/un.rb
+++ b/lib/un.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # = un.rb
 #
diff --git a/lib/unicode_normalize.rb b/lib/unicode_normalize.rb
index e79f41d1a273ef..8daf7b301a8849 100644
--- a/lib/unicode_normalize.rb
+++ b/lib/unicode_normalize.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 # Copyright Ayumu Nojima (野島 歩) and Martin J. Dürst (duerst@it.aoyama.ac.jp)
 
diff --git a/lib/unicode_normalize/normalize.rb b/lib/unicode_normalize/normalize.rb
index 18080ce03de64c..8f0e8a20d11801 100644
--- a/lib/unicode_normalize/normalize.rb
+++ b/lib/unicode_normalize/normalize.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 # Copyright Ayumu Nojima (野島 歩) and Martin J. Dürst (duerst@it.aoyama.ac.jp)
 
diff --git a/lib/uri.rb b/lib/uri.rb
index 2a486214719201..971a97038fd9fb 100644
--- a/lib/uri.rb
+++ b/lib/uri.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # URI is a module providing classes to handle Uniform Resource Identifiers
 # (RFC2396[http://tools.ietf.org/html/rfc2396])
 #
diff --git a/lib/uri/common.rb b/lib/uri/common.rb
index 28b5c997892106..4c7d112e614516 100644
--- a/lib/uri/common.rb
+++ b/lib/uri/common.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # = uri/common.rb
 #
diff --git a/lib/uri/ftp.rb b/lib/uri/ftp.rb
index a90e9b20fde335..e5c00b34da2ca4 100644
--- a/lib/uri/ftp.rb
+++ b/lib/uri/ftp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = uri/ftp.rb
 #
 # Author:: Akira Yamada <akira@ruby-lang.org>
diff --git a/lib/uri/http.rb b/lib/uri/http.rb
index dc47613cdfca96..d43e9a28e091fe 100644
--- a/lib/uri/http.rb
+++ b/lib/uri/http.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = uri/http.rb
 #
 # Author:: Akira Yamada <akira@ruby-lang.org>
diff --git a/lib/uri/https.rb b/lib/uri/https.rb
index 7d242e7e793716..3c8c905cc3e171 100644
--- a/lib/uri/https.rb
+++ b/lib/uri/https.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = uri/https.rb
 #
 # Author:: Akira Yamada <akira@ruby-lang.org>
diff --git a/lib/uri/ldap.rb b/lib/uri/ldap.rb
index 56d748e59edd56..4345875e28a12a 100644
--- a/lib/uri/ldap.rb
+++ b/lib/uri/ldap.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = uri/ldap.rb
 #
 # Author::
diff --git a/lib/uri/ldaps.rb b/lib/uri/ldaps.rb
index 42bbfe86badfd7..d03f8efa2d8890 100644
--- a/lib/uri/ldaps.rb
+++ b/lib/uri/ldaps.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = uri/ldap.rb
 #
 # License:: You can redistribute it and/or modify it under the same term as Ruby.
diff --git a/lib/uri/mailto.rb b/lib/uri/mailto.rb
index b4405630a97473..495f939a3b0971 100644
--- a/lib/uri/mailto.rb
+++ b/lib/uri/mailto.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # = uri/mailto.rb
 #
 # Author:: Akira Yamada <akira@ruby-lang.org>
diff --git a/lib/uri/rfc2396_parser.rb b/lib/uri/rfc2396_parser.rb
index a8af37502a8b9d..b9e7b2b26ef6c5 100644
--- a/lib/uri/rfc2396_parser.rb
+++ b/lib/uri/rfc2396_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # = uri/common.rb
 #
diff --git a/lib/uri/rfc3986_parser.rb b/lib/uri/rfc3986_parser.rb
index 3923b0699c0d7d..871280044adfad 100644
--- a/lib/uri/rfc3986_parser.rb
+++ b/lib/uri/rfc3986_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module URI
   class RFC3986_Parser # :nodoc:
     # URI defined in RFC3986
diff --git a/lib/weakref.rb b/lib/weakref.rb
index cdcbabf77caa79..cdfbe4a679bd53 100644
--- a/lib/weakref.rb
+++ b/lib/weakref.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "delegate"
 
 # Weak Reference class that allows a referenced object to be
diff --git a/lib/webrick.rb b/lib/webrick.rb
index fd8522a6c5ff5a..b7f327ca3377e9 100644
--- a/lib/webrick.rb
+++ b/lib/webrick.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # = WEB server toolkit.
 #
diff --git a/lib/webrick/accesslog.rb b/lib/webrick/accesslog.rb
index 4df27efc291adf..17e5b38ac93c9f 100644
--- a/lib/webrick/accesslog.rb
+++ b/lib/webrick/accesslog.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # accesslog.rb -- Access log handling utilities
 #
diff --git a/lib/webrick/cgi.rb b/lib/webrick/cgi.rb
index 80f636edc3d9cf..94f385f1dd65d0 100644
--- a/lib/webrick/cgi.rb
+++ b/lib/webrick/cgi.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # cgi.rb -- Yet another CGI library
 #
diff --git a/lib/webrick/compat.rb b/lib/webrick/compat.rb
index d2bc3ef6b4b852..c497a1933c92af 100644
--- a/lib/webrick/compat.rb
+++ b/lib/webrick/compat.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # compat.rb -- cross platform compatibility
 #
diff --git a/lib/webrick/config.rb b/lib/webrick/config.rb
index c347da4be6afe7..5f7b0a7fa4c926 100644
--- a/lib/webrick/config.rb
+++ b/lib/webrick/config.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # config.rb -- Default configurations.
 #
diff --git a/lib/webrick/cookie.rb b/lib/webrick/cookie.rb
index d8df23133de5f9..16f8d218275bf7 100644
--- a/lib/webrick/cookie.rb
+++ b/lib/webrick/cookie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # cookie.rb -- Cookie class
 #
diff --git a/lib/webrick/htmlutils.rb b/lib/webrick/htmlutils.rb
index 4cb3d0d7f652d7..ed9f4ac0d3e97c 100644
--- a/lib/webrick/htmlutils.rb
+++ b/lib/webrick/htmlutils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # htmlutils.rb -- HTMLUtils Module
 #
diff --git a/lib/webrick/httpauth.rb b/lib/webrick/httpauth.rb
index 96d479b2d7e04a..bbb67765284801 100644
--- a/lib/webrick/httpauth.rb
+++ b/lib/webrick/httpauth.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpauth.rb -- HTTP access authentication
 #
diff --git a/lib/webrick/httpauth/authenticator.rb b/lib/webrick/httpauth/authenticator.rb
index f6d4ab844f9387..8655118a04c0d1 100644
--- a/lib/webrick/httpauth/authenticator.rb
+++ b/lib/webrick/httpauth/authenticator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # httpauth/authenticator.rb -- Authenticator mix-in module.
 #
diff --git a/lib/webrick/httpauth/basicauth.rb b/lib/webrick/httpauth/basicauth.rb
index ed5dcd1fcdb971..e23420fdfa31df 100644
--- a/lib/webrick/httpauth/basicauth.rb
+++ b/lib/webrick/httpauth/basicauth.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpauth/basicauth.rb -- HTTP basic access authentication
 #
diff --git a/lib/webrick/httpauth/digestauth.rb b/lib/webrick/httpauth/digestauth.rb
index d94bd890ebb378..018989e6dd5c51 100644
--- a/lib/webrick/httpauth/digestauth.rb
+++ b/lib/webrick/httpauth/digestauth.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpauth/digestauth.rb -- HTTP digest access authentication
 #
diff --git a/lib/webrick/httpauth/htdigest.rb b/lib/webrick/httpauth/htdigest.rb
index 5fb0635e2a1259..4bb25e1724b3a4 100644
--- a/lib/webrick/httpauth/htdigest.rb
+++ b/lib/webrick/httpauth/htdigest.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpauth/htdigest.rb -- Apache compatible htdigest file
 #
diff --git a/lib/webrick/httpauth/htgroup.rb b/lib/webrick/httpauth/htgroup.rb
index 0ecabef820125e..832ae8bd040a97 100644
--- a/lib/webrick/httpauth/htgroup.rb
+++ b/lib/webrick/httpauth/htgroup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpauth/htgroup.rb -- Apache compatible htgroup file
 #
diff --git a/lib/webrick/httpauth/htpasswd.rb b/lib/webrick/httpauth/htpasswd.rb
index 69b739fbfe96f2..f43fc2c548a6c7 100644
--- a/lib/webrick/httpauth/htpasswd.rb
+++ b/lib/webrick/httpauth/htpasswd.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpauth/htpasswd -- Apache compatible htpasswd file
 #
diff --git a/lib/webrick/httpauth/userdb.rb b/lib/webrick/httpauth/userdb.rb
index 005c18dfd08f51..7a17715cdf3951 100644
--- a/lib/webrick/httpauth/userdb.rb
+++ b/lib/webrick/httpauth/userdb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # httpauth/userdb.rb -- UserDB mix-in module.
 #
diff --git a/lib/webrick/httpproxy.rb b/lib/webrick/httpproxy.rb
index 075d9c494d4283..79a2e8f55b0874 100644
--- a/lib/webrick/httpproxy.rb
+++ b/lib/webrick/httpproxy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpproxy.rb -- HTTPProxy Class
 #
diff --git a/lib/webrick/httprequest.rb b/lib/webrick/httprequest.rb
index 6aa2d1c1f26d6c..88cdec8a52c8d4 100644
--- a/lib/webrick/httprequest.rb
+++ b/lib/webrick/httprequest.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httprequest.rb -- HTTPRequest Class
 #
diff --git a/lib/webrick/httpresponse.rb b/lib/webrick/httpresponse.rb
index e897e8c01b16ac..5fd54b77c76890 100644
--- a/lib/webrick/httpresponse.rb
+++ b/lib/webrick/httpresponse.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpresponse.rb -- HTTPResponse Class
 #
diff --git a/lib/webrick/https.rb b/lib/webrick/https.rb
index 9194f9411c0ecd..73875d73262369 100644
--- a/lib/webrick/https.rb
+++ b/lib/webrick/https.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # https.rb -- SSL/TLS enhancement for HTTPServer
 #
diff --git a/lib/webrick/httpserver.rb b/lib/webrick/httpserver.rb
index 96bd3fa5482314..b27f2311bdeacf 100644
--- a/lib/webrick/httpserver.rb
+++ b/lib/webrick/httpserver.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpserver.rb -- HTTPServer Class
 #
diff --git a/lib/webrick/httpservlet.rb b/lib/webrick/httpservlet.rb
index ac7c022bd75e06..1ee04ec86fd5fc 100644
--- a/lib/webrick/httpservlet.rb
+++ b/lib/webrick/httpservlet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpservlet.rb -- HTTPServlet Utility File
 #
diff --git a/lib/webrick/httpservlet/abstract.rb b/lib/webrick/httpservlet/abstract.rb
index d3b00ab4e1b69e..ee558eb02606ee 100644
--- a/lib/webrick/httpservlet/abstract.rb
+++ b/lib/webrick/httpservlet/abstract.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httpservlet.rb -- HTTPServlet Module
 #
diff --git a/lib/webrick/httpservlet/cgi_runner.rb b/lib/webrick/httpservlet/cgi_runner.rb
index 32ecb6fe00cd3c..597f48936b0ce5 100644
--- a/lib/webrick/httpservlet/cgi_runner.rb
+++ b/lib/webrick/httpservlet/cgi_runner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # cgi_runner.rb -- CGI launcher.
 #
diff --git a/lib/webrick/httpservlet/cgihandler.rb b/lib/webrick/httpservlet/cgihandler.rb
index 32100418e66cef..051bb7cfcc8d7f 100644
--- a/lib/webrick/httpservlet/cgihandler.rb
+++ b/lib/webrick/httpservlet/cgihandler.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # cgihandler.rb -- CGIHandler Class
 #
diff --git a/lib/webrick/httpservlet/erbhandler.rb b/lib/webrick/httpservlet/erbhandler.rb
index 1b8a82d67b65d3..9bcec698831739 100644
--- a/lib/webrick/httpservlet/erbhandler.rb
+++ b/lib/webrick/httpservlet/erbhandler.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # erbhandler.rb -- ERBHandler Class
 #
diff --git a/lib/webrick/httpservlet/filehandler.rb b/lib/webrick/httpservlet/filehandler.rb
index cc9db4a8707631..068246c9d0290e 100644
--- a/lib/webrick/httpservlet/filehandler.rb
+++ b/lib/webrick/httpservlet/filehandler.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # filehandler.rb -- FileHandler Module
 #
diff --git a/lib/webrick/httpservlet/prochandler.rb b/lib/webrick/httpservlet/prochandler.rb
index 2f5aa66f45356e..c1f454e2f6f487 100644
--- a/lib/webrick/httpservlet/prochandler.rb
+++ b/lib/webrick/httpservlet/prochandler.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # prochandler.rb -- ProcHandler Class
 #
diff --git a/lib/webrick/httpstatus.rb b/lib/webrick/httpstatus.rb
index 7ffda64cf0f92f..8664da26d0ee2a 100644
--- a/lib/webrick/httpstatus.rb
+++ b/lib/webrick/httpstatus.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # httpstatus.rb -- HTTPStatus Class
 #
diff --git a/lib/webrick/httputils.rb b/lib/webrick/httputils.rb
index a5f0632b86377b..28f906ef4d34cc 100644
--- a/lib/webrick/httputils.rb
+++ b/lib/webrick/httputils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # httputils.rb -- HTTPUtils Module
 #
diff --git a/lib/webrick/httpversion.rb b/lib/webrick/httpversion.rb
index cdfb957296bd14..8a251944a2c067 100644
--- a/lib/webrick/httpversion.rb
+++ b/lib/webrick/httpversion.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # HTTPVersion.rb -- presentation of HTTP version
 #
diff --git a/lib/webrick/log.rb b/lib/webrick/log.rb
index 41cde4a7408412..7542d8f79a992b 100644
--- a/lib/webrick/log.rb
+++ b/lib/webrick/log.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # log.rb -- Log Class
 #
diff --git a/lib/webrick/server.rb b/lib/webrick/server.rb
index 73395a406d8272..e2e99bfc5ff8a4 100644
--- a/lib/webrick/server.rb
+++ b/lib/webrick/server.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # server.rb -- GenericServer Class
 #
diff --git a/lib/webrick/ssl.rb b/lib/webrick/ssl.rb
index b69a836f5dd54c..8eb3a442dac7b6 100644
--- a/lib/webrick/ssl.rb
+++ b/lib/webrick/ssl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # ssl.rb -- SSL/TLS enhancement for GenericServer
 #
diff --git a/lib/webrick/utils.rb b/lib/webrick/utils.rb
index 654d9dea9518e6..f7b4412c1924d6 100644
--- a/lib/webrick/utils.rb
+++ b/lib/webrick/utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # utils.rb -- Miscellaneous utilities
 #
diff --git a/lib/webrick/version.rb b/lib/webrick/version.rb
index 48bdc6d94d00cd..da5dac94a937dc 100644
--- a/lib/webrick/version.rb
+++ b/lib/webrick/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # version.rb -- version and release date
 #
diff --git a/lib/xmlrpc.rb b/lib/xmlrpc.rb
index 8cad6a10995b28..aa24afacac8e14 100644
--- a/lib/xmlrpc.rb
+++ b/lib/xmlrpc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # == Author and Copyright
 #
 # Copyright (C) 2001-2004 by Michael Neumann (mailto:mneumann@ntecs.de)
diff --git a/lib/xmlrpc/base64.rb b/lib/xmlrpc/base64.rb
index 4aac3520c57d09..21f8c65ce2527b 100644
--- a/lib/xmlrpc/base64.rb
+++ b/lib/xmlrpc/base64.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # xmlrpc/base64.rb
 # Copyright (C) 2001, 2002, 2003 by Michael Neumann (mneumann@ntecs.de)
diff --git a/lib/xmlrpc/client.rb b/lib/xmlrpc/client.rb
index aab07a7f956657..3cb9e9a9e95d64 100644
--- a/lib/xmlrpc/client.rb
+++ b/lib/xmlrpc/client.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # xmlrpc/client.rb
 # Copyright (C) 2001, 2002, 2003 by Michael Neumann (mneumann@ntecs.de)
 #
diff --git a/lib/xmlrpc/config.rb b/lib/xmlrpc/config.rb
index 7923f3a26efbf9..f49adb6892cdc8 100644
--- a/lib/xmlrpc/config.rb
+++ b/lib/xmlrpc/config.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # $Id$
 # Configuration file for XML-RPC for Ruby
diff --git a/lib/xmlrpc/create.rb b/lib/xmlrpc/create.rb
index 13c9cd8faa81b9..93822c4dd2f8a3 100644
--- a/lib/xmlrpc/create.rb
+++ b/lib/xmlrpc/create.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Copyright (C) 2001, 2002, 2003 by Michael Neumann (mneumann@ntecs.de)
 #
diff --git a/lib/xmlrpc/datetime.rb b/lib/xmlrpc/datetime.rb
index 444a29f176d87d..431ac24aa93e23 100644
--- a/lib/xmlrpc/datetime.rb
+++ b/lib/xmlrpc/datetime.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # xmlrpc/datetime.rb
 # Copyright (C) 2001, 2002, 2003 by Michael Neumann (mneumann@ntecs.de)
diff --git a/lib/xmlrpc/marshal.rb b/lib/xmlrpc/marshal.rb
index ef1234f80156f6..42b7b1e125bb0f 100644
--- a/lib/xmlrpc/marshal.rb
+++ b/lib/xmlrpc/marshal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Copyright (C) 2001, 2002, 2003 by Michael Neumann (mneumann@ntecs.de)
 #
diff --git a/lib/xmlrpc/parser.rb b/lib/xmlrpc/parser.rb
index be8accfd6b0e77..3b912b6be2f621 100644
--- a/lib/xmlrpc/parser.rb
+++ b/lib/xmlrpc/parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # Copyright (C) 2001, 2002, 2003 by Michael Neumann (mneumann@ntecs.de)
 #
 # $Id$
diff --git a/lib/xmlrpc/server.rb b/lib/xmlrpc/server.rb
index 64856ea1fa1498..cd0fdbad38bdc5 100644
--- a/lib/xmlrpc/server.rb
+++ b/lib/xmlrpc/server.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # xmlrpc/server.rb
 # Copyright (C) 2001, 2002, 2003, 2005 by Michael Neumann (mneumann@ntecs.de)
 #
diff --git a/lib/xmlrpc/utils.rb b/lib/xmlrpc/utils.rb
index 186938a56ef816..cd2ab107d9072e 100644
--- a/lib/xmlrpc/utils.rb
+++ b/lib/xmlrpc/utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Copyright (C) 2001, 2002, 2003 by Michael Neumann (mneumann@ntecs.de)
 #
diff --git a/lib/yaml.rb b/lib/yaml.rb
index b211ca5a73700d..0c33305e1dca6f 100644
--- a/lib/yaml.rb
+++ b/lib/yaml.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # The YAML module is an alias of Psych, the YAML engine for Ruby.
 
diff --git a/lib/yaml/dbm.rb b/lib/yaml/dbm.rb
index 24a68bfa71ae33..e2508cd74b38c1 100644
--- a/lib/yaml/dbm.rb
+++ b/lib/yaml/dbm.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'yaml'
 require 'dbm'
 
diff --git a/lib/yaml/store.rb b/lib/yaml/store.rb
index b0b580ba1ac9bd..57ef0ba5009db2 100644
--- a/lib/yaml/store.rb
+++ b/lib/yaml/store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # YAML::Store
 #
diff --git a/test/-ext-/array/test_resize.rb b/test/-ext-/array/test_resize.rb
index 8e526b5a0c4c0a..f6a368cb755f86 100644
--- a/test/-ext-/array/test_resize.rb
+++ b/test/-ext-/array/test_resize.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/array/resize'
 
diff --git a/test/-ext-/bignum/test_big2str.rb b/test/-ext-/bignum/test_big2str.rb
index 0af552ea70971a..4fae24eb345533 100644
--- a/test/-ext-/bignum/test_big2str.rb
+++ b/test/-ext-/bignum/test_big2str.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/bignum"
 
diff --git a/test/-ext-/bignum/test_bigzero.rb b/test/-ext-/bignum/test_bigzero.rb
index f75c4590b86fd6..8529e54456bc90 100644
--- a/test/-ext-/bignum/test_bigzero.rb
+++ b/test/-ext-/bignum/test_bigzero.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/bignum"
 
diff --git a/test/-ext-/bignum/test_div.rb b/test/-ext-/bignum/test_div.rb
index 9c1a3c3d2a9a55..9a8e93b081513d 100644
--- a/test/-ext-/bignum/test_div.rb
+++ b/test/-ext-/bignum/test_div.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/bignum"
 
diff --git a/test/-ext-/bignum/test_mul.rb b/test/-ext-/bignum/test_mul.rb
index 3e78247aa45d2c..103a00fbad296e 100644
--- a/test/-ext-/bignum/test_mul.rb
+++ b/test/-ext-/bignum/test_mul.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/bignum"
 
diff --git a/test/-ext-/bignum/test_pack.rb b/test/-ext-/bignum/test_pack.rb
index f2a3df814e0315..04bf3e02de1f22 100644
--- a/test/-ext-/bignum/test_pack.rb
+++ b/test/-ext-/bignum/test_pack.rb
@@ -1,4 +1,5 @@
 # coding: ASCII-8BIT
+# frozen_string_literal: false
 
 require 'test/unit'
 require "-test-/bignum"
diff --git a/test/-ext-/bignum/test_str2big.rb b/test/-ext-/bignum/test_str2big.rb
index 4304be88e9fa7e..3b5750154ead50 100644
--- a/test/-ext-/bignum/test_str2big.rb
+++ b/test/-ext-/bignum/test_str2big.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/bignum"
 
diff --git a/test/-ext-/bug_reporter/test_bug_reporter.rb b/test/-ext-/bug_reporter/test_bug_reporter.rb
index e68adeef06fc57..fb37658c9204dd 100644
--- a/test/-ext-/bug_reporter/test_bug_reporter.rb
+++ b/test/-ext-/bug_reporter/test_bug_reporter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 
diff --git a/test/-ext-/class/test_class2name.rb b/test/-ext-/class/test_class2name.rb
index 070be5a130fbe5..e61964d9eb7365 100644
--- a/test/-ext-/class/test_class2name.rb
+++ b/test/-ext-/class/test_class2name.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/class"
 
diff --git a/test/-ext-/debug/test_debug.rb b/test/-ext-/debug/test_debug.rb
index ec506e0ca527ce..3804714d0dce9b 100644
--- a/test/-ext-/debug/test_debug.rb
+++ b/test/-ext-/debug/test_debug.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/debug'
 
diff --git a/test/-ext-/debug/test_profile_frames.rb b/test/-ext-/debug/test_profile_frames.rb
index e257ef09b3df43..860652c0cdf53c 100644
--- a/test/-ext-/debug/test_profile_frames.rb
+++ b/test/-ext-/debug/test_profile_frames.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/debug'
 
diff --git a/test/-ext-/exception/test_data_error.rb b/test/-ext-/exception/test_data_error.rb
index 53cbb28438f470..d33d8ca43fd425 100644
--- a/test/-ext-/exception/test_data_error.rb
+++ b/test/-ext-/exception/test_data_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module Bug
diff --git a/test/-ext-/exception/test_enc_raise.rb b/test/-ext-/exception/test_enc_raise.rb
index a578b167ea86a6..2bc7f024135a71 100644
--- a/test/-ext-/exception/test_enc_raise.rb
+++ b/test/-ext-/exception/test_enc_raise.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/exception'
 
diff --git a/test/-ext-/exception/test_ensured.rb b/test/-ext-/exception/test_ensured.rb
index 97d97941862227..858245868b3de0 100644
--- a/test/-ext-/exception/test_ensured.rb
+++ b/test/-ext-/exception/test_ensured.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module Bug
diff --git a/test/-ext-/file/test_stat.rb b/test/-ext-/file/test_stat.rb
index b9aa132932e702..9eebcd97b9f679 100644
--- a/test/-ext-/file/test_stat.rb
+++ b/test/-ext-/file/test_stat.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/file"
 
diff --git a/test/-ext-/float/test_nextafter.rb b/test/-ext-/float/test_nextafter.rb
index e3a3e726c7fa7e..c131d1e4131982 100644
--- a/test/-ext-/float/test_nextafter.rb
+++ b/test/-ext-/float/test_nextafter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/float"
 
diff --git a/test/-ext-/funcall/test_passing_block.rb b/test/-ext-/funcall/test_passing_block.rb
index 87aed2212c80e2..fac7eaf9539fb5 100644
--- a/test/-ext-/funcall/test_passing_block.rb
+++ b/test/-ext-/funcall/test_passing_block.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestFuncall < Test::Unit::TestCase
diff --git a/test/-ext-/gvl/test_last_thread.rb b/test/-ext-/gvl/test_last_thread.rb
index cf5f28f4b61ca0..3b297a5b31189b 100644
--- a/test/-ext-/gvl/test_last_thread.rb
+++ b/test/-ext-/gvl/test_last_thread.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class TestLastThread < Test::Unit::TestCase
 
   # [Bug #11237]
diff --git a/test/-ext-/hash/test_delete.rb b/test/-ext-/hash/test_delete.rb
index 13f359548261b9..e2ad3cbdbc0c8d 100644
--- a/test/-ext-/hash/test_delete.rb
+++ b/test/-ext-/hash/test_delete.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/hash'
 
diff --git a/test/-ext-/iseq_load/test_iseq_load.rb b/test/-ext-/iseq_load/test_iseq_load.rb
index 5dfd69a8634d38..7eb8f4bfc84a65 100644
--- a/test/-ext-/iseq_load/test_iseq_load.rb
+++ b/test/-ext-/iseq_load/test_iseq_load.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestIseqLoad < Test::Unit::TestCase
diff --git a/test/-ext-/iter/test_iter_break.rb b/test/-ext-/iter/test_iter_break.rb
index 5bac6331fdb132..8c2379960a9a4d 100644
--- a/test/-ext-/iter/test_iter_break.rb
+++ b/test/-ext-/iter/test_iter_break.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/iter'
 
diff --git a/test/-ext-/iter/test_yield_block.rb b/test/-ext-/iter/test_yield_block.rb
index bec993c95057f8..d4f1fa3c35a27b 100644
--- a/test/-ext-/iter/test_yield_block.rb
+++ b/test/-ext-/iter/test_yield_block.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/iter'
 
diff --git a/test/-ext-/load/test_dot_dot.rb b/test/-ext-/load/test_dot_dot.rb
index 82aa10a95f0f7b..1b2c8716089fef 100644
--- a/test/-ext-/load/test_dot_dot.rb
+++ b/test/-ext-/load/test_dot_dot.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class Test_DotDot < Test::Unit::TestCase
diff --git a/test/-ext-/marshal/test_internal_ivar.rb b/test/-ext-/marshal/test_internal_ivar.rb
index e0e2a72f54366a..51529667b52b6a 100644
--- a/test/-ext-/marshal/test_internal_ivar.rb
+++ b/test/-ext-/marshal/test_internal_ivar.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/marshal/internal_ivar'
 
diff --git a/test/-ext-/marshal/test_usrmarshal.rb b/test/-ext-/marshal/test_usrmarshal.rb
index 8d8db012acab04..263dcb829740a9 100644
--- a/test/-ext-/marshal/test_usrmarshal.rb
+++ b/test/-ext-/marshal/test_usrmarshal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/marshal/usr'
 
diff --git a/test/-ext-/method/test_arity.rb b/test/-ext-/method/test_arity.rb
index 79ef23b34ff93a..d0032c6a50c0bb 100644
--- a/test/-ext-/method/test_arity.rb
+++ b/test/-ext-/method/test_arity.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require '-test-/method'
 require 'test/unit'
 
diff --git a/test/-ext-/num2int/test_num2int.rb b/test/-ext-/num2int/test_num2int.rb
index f5796599291389..c00bb56833d050 100644
--- a/test/-ext-/num2int/test_num2int.rb
+++ b/test/-ext-/num2int/test_num2int.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/num2int/num2int'
 
diff --git a/test/-ext-/path_to_class/test_path_to_class.rb b/test/-ext-/path_to_class/test_path_to_class.rb
index fdf4097fde1611..57e3a9233a5e4a 100644
--- a/test/-ext-/path_to_class/test_path_to_class.rb
+++ b/test/-ext-/path_to_class/test_path_to_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class Test_PathToClass < Test::Unit::TestCase
diff --git a/test/-ext-/popen_deadlock/test_popen_deadlock.rb b/test/-ext-/popen_deadlock/test_popen_deadlock.rb
index 60ec6ccce43610..97892e50083176 100644
--- a/test/-ext-/popen_deadlock/test_popen_deadlock.rb
+++ b/test/-ext-/popen_deadlock/test_popen_deadlock.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require '-test-/popen_deadlock/infinite_loop_dlsym'
 rescue LoadError
diff --git a/test/-ext-/postponed_job/test_postponed_job.rb b/test/-ext-/postponed_job/test_postponed_job.rb
index 032e35c055a589..da3b579ebae33c 100644
--- a/test/-ext-/postponed_job/test_postponed_job.rb
+++ b/test/-ext-/postponed_job/test_postponed_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'thread'
 require '-test-/postponed_job'
diff --git a/test/-ext-/proc/test_bmethod.rb b/test/-ext-/proc/test_bmethod.rb
index 16927dcf7d7c7a..344f9757559cb8 100644
--- a/test/-ext-/proc/test_bmethod.rb
+++ b/test/-ext-/proc/test_bmethod.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/proc'
 
diff --git a/test/-ext-/rational/test_rat.rb b/test/-ext-/rational/test_rat.rb
index ef7e7fe535ac0d..626ffb96611f91 100644
--- a/test/-ext-/rational/test_rat.rb
+++ b/test/-ext-/rational/test_rat.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/rational"
 
diff --git a/test/-ext-/st/test_foreach.rb b/test/-ext-/st/test_foreach.rb
index 259b0a93b127ae..4b3eb870e4839b 100644
--- a/test/-ext-/st/test_foreach.rb
+++ b/test/-ext-/st/test_foreach.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/st/foreach'
 
diff --git a/test/-ext-/st/test_numhash.rb b/test/-ext-/st/test_numhash.rb
index 24dc87c1d9dfe7..97c3a755bbcd0f 100644
--- a/test/-ext-/st/test_numhash.rb
+++ b/test/-ext-/st/test_numhash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/st/numhash"
 
diff --git a/test/-ext-/st/test_update.rb b/test/-ext-/st/test_update.rb
index 1b41d2bc03fb8a..db86eeb8d7ed41 100644
--- a/test/-ext-/st/test_update.rb
+++ b/test/-ext-/st/test_update.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/st/update"
 
diff --git a/test/-ext-/string/test_coderange.rb b/test/-ext-/string/test_coderange.rb
index 31f5c871f56b5e..18b256fcea3826 100644
--- a/test/-ext-/string/test_coderange.rb
+++ b/test/-ext-/string/test_coderange.rb
@@ -1,4 +1,5 @@
 # coding: ascii-8bit
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 require "rbconfig/sizeof"
diff --git a/test/-ext-/string/test_cstr.rb b/test/-ext-/string/test_cstr.rb
index 4be2cc98fa23d9..f4ed520b2d5835 100644
--- a/test/-ext-/string/test_cstr.rb
+++ b/test/-ext-/string/test_cstr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 
diff --git a/test/-ext-/string/test_ellipsize.rb b/test/-ext-/string/test_ellipsize.rb
index 23ccdb515b2773..d7947041d56336 100644
--- a/test/-ext-/string/test_ellipsize.rb
+++ b/test/-ext-/string/test_ellipsize.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 
diff --git a/test/-ext-/string/test_enc_associate.rb b/test/-ext-/string/test_enc_associate.rb
index 2c84f49db183a9..4fad8e1cc87991 100644
--- a/test/-ext-/string/test_enc_associate.rb
+++ b/test/-ext-/string/test_enc_associate.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 
diff --git a/test/-ext-/string/test_enc_str_buf_cat.rb b/test/-ext-/string/test_enc_str_buf_cat.rb
index c925affb4194c8..72f903903c7b10 100644
--- a/test/-ext-/string/test_enc_str_buf_cat.rb
+++ b/test/-ext-/string/test_enc_str_buf_cat.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 
diff --git a/test/-ext-/string/test_fstring.rb b/test/-ext-/string/test_fstring.rb
index 3ad9a4c312ef42..39ed0208923cc0 100644
--- a/test/-ext-/string/test_fstring.rb
+++ b/test/-ext-/string/test_fstring.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/string'
 
diff --git a/test/-ext-/string/test_modify_expand.rb b/test/-ext-/string/test_modify_expand.rb
index cc19a47b91728c..5eb7a02b91a656 100644
--- a/test/-ext-/string/test_modify_expand.rb
+++ b/test/-ext-/string/test_modify_expand.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 
diff --git a/test/-ext-/string/test_nofree.rb b/test/-ext-/string/test_nofree.rb
index cb034a4b8f6e57..86681e46523391 100644
--- a/test/-ext-/string/test_nofree.rb
+++ b/test/-ext-/string/test_nofree.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class Test_StringNoFree < Test::Unit::TestCase
diff --git a/test/-ext-/string/test_normalize.rb b/test/-ext-/string/test_normalize.rb
index b270a450058c49..8c11bfe3d424a6 100644
--- a/test/-ext-/string/test_normalize.rb
+++ b/test/-ext-/string/test_normalize.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 require "tempfile"
diff --git a/test/-ext-/string/test_qsort.rb b/test/-ext-/string/test_qsort.rb
index 1a6dae0124b100..94aff8c3c45ea4 100644
--- a/test/-ext-/string/test_qsort.rb
+++ b/test/-ext-/string/test_qsort.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 
diff --git a/test/-ext-/string/test_set_len.rb b/test/-ext-/string/test_set_len.rb
index 198129d72ff82f..1c5252a5f65d56 100644
--- a/test/-ext-/string/test_set_len.rb
+++ b/test/-ext-/string/test_set_len.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/string"
 
diff --git a/test/-ext-/struct/test_member.rb b/test/-ext-/struct/test_member.rb
index 18e98085a0749b..5ee0adcf6769f3 100644
--- a/test/-ext-/struct/test_member.rb
+++ b/test/-ext-/struct/test_member.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/struct"
 
diff --git a/test/-ext-/symbol/test_inadvertent_creation.rb b/test/-ext-/symbol/test_inadvertent_creation.rb
index 14afc90d74027a..073952fae33b5e 100644
--- a/test/-ext-/symbol/test_inadvertent_creation.rb
+++ b/test/-ext-/symbol/test_inadvertent_creation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/symbol"
 
diff --git a/test/-ext-/symbol/test_type.rb b/test/-ext-/symbol/test_type.rb
index ddd79561ab7507..32a700d2732013 100644
--- a/test/-ext-/symbol/test_type.rb
+++ b/test/-ext-/symbol/test_type.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/symbol"
 
diff --git a/test/-ext-/test_bug-3571.rb b/test/-ext-/test_bug-3571.rb
index d7c26d1ff0f038..dc9c92bd233e0b 100644
--- a/test/-ext-/test_bug-3571.rb
+++ b/test/-ext-/test_bug-3571.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class Test_BUG_3571 < Test::Unit::TestCase
diff --git a/test/-ext-/test_bug-5832.rb b/test/-ext-/test_bug-5832.rb
index 11f8a52a95c6f0..6812e64e5e5409 100644
--- a/test/-ext-/test_bug-5832.rb
+++ b/test/-ext-/test_bug-5832.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require '-test-/bug-5832/bug'
 
 class Test_BUG_5832 < Test::Unit::TestCase
diff --git a/test/-ext-/test_notimplement.rb b/test/-ext-/test_notimplement.rb
index 7394126fb169e5..0eba7bdaf8c4a3 100644
--- a/test/-ext-/test_notimplement.rb
+++ b/test/-ext-/test_notimplement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require '-test-/notimplement'
 
 class TestNotImplement < Test::Unit::TestCase
diff --git a/test/-ext-/test_printf.rb b/test/-ext-/test_printf.rb
index 1f06ad6300c14c..4e4f5b4695153c 100644
--- a/test/-ext-/test_printf.rb
+++ b/test/-ext-/test_printf.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/printf"
 require_relative '../ruby/allpairs'
diff --git a/test/-ext-/test_recursion.rb b/test/-ext-/test_recursion.rb
index 06faf6dc7a5103..db7a8539886721 100644
--- a/test/-ext-/test_recursion.rb
+++ b/test/-ext-/test_recursion.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestRecursion < Test::Unit::TestCase
diff --git a/test/-ext-/time/test_new.rb b/test/-ext-/time/test_new.rb
index 5ccf6f0a5d98cc..699201fda59047 100644
--- a/test/-ext-/time/test_new.rb
+++ b/test/-ext-/time/test_new.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/time"
 
diff --git a/test/-ext-/tracepoint/test_tracepoint.rb b/test/-ext-/tracepoint/test_tracepoint.rb
index b5a6e769d6a47a..33d0c3e8e158f1 100644
--- a/test/-ext-/tracepoint/test_tracepoint.rb
+++ b/test/-ext-/tracepoint/test_tracepoint.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require '-test-/tracepoint'
 
diff --git a/test/-ext-/typeddata/test_typeddata.rb b/test/-ext-/typeddata/test_typeddata.rb
index 31fe32b20a4c3d..058b7b70c5e932 100644
--- a/test/-ext-/typeddata/test_typeddata.rb
+++ b/test/-ext-/typeddata/test_typeddata.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "-test-/typeddata/typeddata"
 
diff --git a/test/-ext-/wait_for_single_fd/test_wait_for_single_fd.rb b/test/-ext-/wait_for_single_fd/test_wait_for_single_fd.rb
index e88dbefac69011..d9fc52ebb22d9b 100644
--- a/test/-ext-/wait_for_single_fd/test_wait_for_single_fd.rb
+++ b/test/-ext-/wait_for_single_fd/test_wait_for_single_fd.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestWaitForSingleFD < Test::Unit::TestCase
diff --git a/test/-ext-/win32/test_console_attr.rb b/test/-ext-/win32/test_console_attr.rb
index 3afb2d93789ac9..e596e13469c774 100644
--- a/test/-ext-/win32/test_console_attr.rb
+++ b/test/-ext-/win32/test_console_attr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 if /mswin|mingw/ =~ RUBY_PLATFORM and STDOUT.tty?
   require '-test-/win32/console'
   require 'io/console'
diff --git a/test/-ext-/win32/test_dln.rb b/test/-ext-/win32/test_dln.rb
index fe289d150f96f3..fd5e453719e3c3 100644
--- a/test/-ext-/win32/test_dln.rb
+++ b/test/-ext-/win32/test_dln.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 require 'rbconfig'
diff --git a/test/-ext-/win32/test_fd_setsize.rb b/test/-ext-/win32/test_fd_setsize.rb
index 6fe889c941d48d..4c64376f156ec4 100644
--- a/test/-ext-/win32/test_fd_setsize.rb
+++ b/test/-ext-/win32/test_fd_setsize.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module Bug
diff --git a/test/base64/test_base64.rb b/test/base64/test_base64.rb
index c2cd60adcd06fc..8e11bef9a69bde 100644
--- a/test/base64/test_base64.rb
+++ b/test/base64/test_base64.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require "test/unit"
 require "base64"
 
diff --git a/test/benchmark/test_benchmark.rb b/test/benchmark/test_benchmark.rb
index 1b9964eafa6bd9..2db148304c51bf 100644
--- a/test/benchmark/test_benchmark.rb
+++ b/test/benchmark/test_benchmark.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'benchmark'
 
diff --git a/test/bigdecimal/test_bigdecimal.rb b/test/bigdecimal/test_bigdecimal.rb
index edbaa163b45177..f10c50b47a9f97 100644
--- a/test/bigdecimal/test_bigdecimal.rb
+++ b/test/bigdecimal/test_bigdecimal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "testbase"
 require 'bigdecimal/math'
 
diff --git a/test/bigdecimal/test_bigdecimal_util.rb b/test/bigdecimal/test_bigdecimal_util.rb
index e4d64006ab10af..c3a45b2eeea008 100644
--- a/test/bigdecimal/test_bigdecimal_util.rb
+++ b/test/bigdecimal/test_bigdecimal_util.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "testbase"
 
 require 'bigdecimal/util'
diff --git a/test/bigdecimal/test_bigmath.rb b/test/bigdecimal/test_bigmath.rb
index 740c755eae6d85..6f271d0960fa42 100644
--- a/test/bigdecimal/test_bigmath.rb
+++ b/test/bigdecimal/test_bigmath.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "testbase"
 require "bigdecimal/math"
 
diff --git a/test/bigdecimal/testbase.rb b/test/bigdecimal/testbase.rb
index c014e61e92cfac..22b05f09ae423c 100644
--- a/test/bigdecimal/testbase.rb
+++ b/test/bigdecimal/testbase.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "bigdecimal"
 
diff --git a/test/cgi/test_cgi_cookie.rb b/test/cgi/test_cgi_cookie.rb
index eee6215facfd64..ae7b14a4ddd719 100644
--- a/test/cgi/test_cgi_cookie.rb
+++ b/test/cgi/test_cgi_cookie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cgi'
 require 'stringio'
diff --git a/test/cgi/test_cgi_core.rb b/test/cgi/test_cgi_core.rb
index 68e008d3f129a3..97308a0457330b 100644
--- a/test/cgi/test_cgi_core.rb
+++ b/test/cgi/test_cgi_core.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cgi'
 require 'stringio'
diff --git a/test/cgi/test_cgi_header.rb b/test/cgi/test_cgi_header.rb
index 91086c4f27524d..b1a0b41856b80e 100644
--- a/test/cgi/test_cgi_header.rb
+++ b/test/cgi/test_cgi_header.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cgi'
 require 'time'
diff --git a/test/cgi/test_cgi_modruby.rb b/test/cgi/test_cgi_modruby.rb
index ed1d519bae900b..9813a95277ec90 100644
--- a/test/cgi/test_cgi_modruby.rb
+++ b/test/cgi/test_cgi_modruby.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cgi'
 require_relative 'update_env'
diff --git a/test/cgi/test_cgi_multipart.rb b/test/cgi/test_cgi_multipart.rb
index b3df6948491a21..f63c2e37780a73 100644
--- a/test/cgi/test_cgi_multipart.rb
+++ b/test/cgi/test_cgi_multipart.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cgi'
 require 'tempfile'
diff --git a/test/cgi/test_cgi_session.rb b/test/cgi/test_cgi_session.rb
index c2d7bdc60dc5c5..59e8d4c15bb882 100644
--- a/test/cgi/test_cgi_session.rb
+++ b/test/cgi/test_cgi_session.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cgi'
 require 'cgi/session'
diff --git a/test/cgi/test_cgi_tag_helper.rb b/test/cgi/test_cgi_tag_helper.rb
index cc119cb1bcc6d8..a48bafdaecc06c 100644
--- a/test/cgi/test_cgi_tag_helper.rb
+++ b/test/cgi/test_cgi_tag_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cgi'
 require 'stringio'
diff --git a/test/cgi/test_cgi_util.rb b/test/cgi/test_cgi_util.rb
index 2c5182b524fe46..5662a30eff9d6c 100644
--- a/test/cgi/test_cgi_util.rb
+++ b/test/cgi/test_cgi_util.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cgi'
 require 'stringio'
diff --git a/test/cgi/update_env.rb b/test/cgi/update_env.rb
index 0cd926d7af4895..cbc8dc13c6ee2d 100644
--- a/test/cgi/update_env.rb
+++ b/test/cgi/update_env.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module UpdateEnv
   def update_env(environ)
     environ.each do |key, val|
diff --git a/test/coverage/test_coverage.rb b/test/coverage/test_coverage.rb
index b7a7ea7dab2b4e..4870b1006ad57c 100644
--- a/test/coverage/test_coverage.rb
+++ b/test/coverage/test_coverage.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "coverage"
 require "tmpdir"
diff --git a/test/csv/base.rb b/test/csv/base.rb
index 621569e01317c1..a282c7afed569d 100644
--- a/test/csv/base.rb
+++ b/test/csv/base.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 
 require "csv"
diff --git a/test/csv/test_csv_parsing.rb b/test/csv/test_csv_parsing.rb
index 319f3f392f63e4..ff3d65fd242797 100755
--- a/test/csv/test_csv_parsing.rb
+++ b/test/csv/test_csv_parsing.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_csv_parsing.rb
 #
diff --git a/test/csv/test_csv_writing.rb b/test/csv/test_csv_writing.rb
index 704c1d7ddc32f9..de82dae2440d3d 100755
--- a/test/csv/test_csv_writing.rb
+++ b/test/csv/test_csv_writing.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_csv_writing.rb
 #
diff --git a/test/csv/test_data_converters.rb b/test/csv/test_data_converters.rb
index 89b6dd1dfd10ee..70f996360ceca0 100755
--- a/test/csv/test_data_converters.rb
+++ b/test/csv/test_data_converters.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_data_converters.rb
 #
diff --git a/test/csv/test_encodings.rb b/test/csv/test_encodings.rb
index dc45692ce482a1..7460a3ff34ba2c 100755
--- a/test/csv/test_encodings.rb
+++ b/test/csv/test_encodings.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_encodings.rb
 #
diff --git a/test/csv/test_features.rb b/test/csv/test_features.rb
index e31465710b5287..37fdab8636dc47 100755
--- a/test/csv/test_features.rb
+++ b/test/csv/test_features.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_features.rb
 #
diff --git a/test/csv/test_headers.rb b/test/csv/test_headers.rb
index 79ccd20c74944e..d8a1c15836fe45 100755
--- a/test/csv/test_headers.rb
+++ b/test/csv/test_headers.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_headers.rb
 #
diff --git a/test/csv/test_interface.rb b/test/csv/test_interface.rb
index d6bf470f6bf5b0..a12545c8b05be2 100755
--- a/test/csv/test_interface.rb
+++ b/test/csv/test_interface.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_interface.rb
 #
diff --git a/test/csv/test_row.rb b/test/csv/test_row.rb
index a8aeb288fc14c8..1fa15d392ade3c 100755
--- a/test/csv/test_row.rb
+++ b/test/csv/test_row.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_row.rb
 #
diff --git a/test/csv/test_table.rb b/test/csv/test_table.rb
index 7d2148c379cf58..80e553e83f3c4e 100755
--- a/test/csv/test_table.rb
+++ b/test/csv/test_table.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # tc_table.rb
 #
diff --git a/test/csv/ts_all.rb b/test/csv/ts_all.rb
index 389384168b8f25..9eadf1291848f9 100644
--- a/test/csv/ts_all.rb
+++ b/test/csv/ts_all.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -w
 # encoding: UTF-8
+# frozen_string_literal: false
 
 # ts_all.rb
 #
diff --git a/test/date/test_date.rb b/test/date/test_date.rb
index 3d8bf868c41073..3bb1f4a4c7c1c4 100644
--- a/test/date/test_date.rb
+++ b/test/date/test_date.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_arith.rb b/test/date/test_date_arith.rb
index 7b79c180978ad1..f5ac5bf30b4cdd 100644
--- a/test/date/test_date_arith.rb
+++ b/test/date/test_date_arith.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_attr.rb b/test/date/test_date_attr.rb
index bc6bec2a804ced..3d1b0a2e6e203f 100644
--- a/test/date/test_date_attr.rb
+++ b/test/date/test_date_attr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_base.rb b/test/date/test_date_base.rb
index 1f3d8c0a554155..06fec19e52e127 100644
--- a/test/date/test_date_base.rb
+++ b/test/date/test_date_base.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_compat.rb b/test/date/test_date_compat.rb
index 8284007407c3eb..1bd30b5f8083ac 100644
--- a/test/date/test_date_compat.rb
+++ b/test/date/test_date_compat.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_conv.rb b/test/date/test_date_conv.rb
index daf0374294e1e9..8b99970dd7e370 100644
--- a/test/date/test_date_conv.rb
+++ b/test/date/test_date_conv.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_marshal.rb b/test/date/test_date_marshal.rb
index 4ea5565716e127..27ae1e90044727 100644
--- a/test/date/test_date_marshal.rb
+++ b/test/date/test_date_marshal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_new.rb b/test/date/test_date_new.rb
index 0bbbfee44ba192..80ecbc204e03f5 100644
--- a/test/date/test_date_new.rb
+++ b/test/date/test_date_new.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_parse.rb b/test/date/test_date_parse.rb
index e0cd6025a8ac4e..d980674591c2d6 100644
--- a/test/date/test_date_parse.rb
+++ b/test/date/test_date_parse.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_strftime.rb b/test/date/test_date_strftime.rb
index 0ed9215e1ec0ad..7472a4323d1ba1 100644
--- a/test/date/test_date_strftime.rb
+++ b/test/date/test_date_strftime.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_date_strptime.rb b/test/date/test_date_strptime.rb
index ae149bb8d845ab..15fdc949f56b52 100644
--- a/test/date/test_date_strptime.rb
+++ b/test/date/test_date_strptime.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/date/test_switch_hitter.rb b/test/date/test_switch_hitter.rb
index 08e23015dcff60..931d736edf1661 100644
--- a/test/date/test_switch_hitter.rb
+++ b/test/date/test_switch_hitter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'date'
 
diff --git a/test/dbm/test_dbm.rb b/test/dbm/test_dbm.rb
index c783b497d89ae8..cd8c3fd8d3890f 100644
--- a/test/dbm/test_dbm.rb
+++ b/test/dbm/test_dbm.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 
diff --git a/test/digest/digest/foo.rb b/test/digest/digest/foo.rb
index d576ef00e087bd..6d42b003fb0724 100644
--- a/test/digest/digest/foo.rb
+++ b/test/digest/digest/foo.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Digest
   Foo = nil
 
diff --git a/test/digest/test_digest.rb b/test/digest/test_digest.rb
index ccf0a26b90014f..039c1701cb6518 100644
--- a/test/digest/test_digest.rb
+++ b/test/digest/test_digest.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $RoughId: test.rb,v 1.4 2001/07/13 15:38:27 knu Exp $
 # $Id$
 
diff --git a/test/digest/test_digest_extend.rb b/test/digest/test_digest_extend.rb
index 46158a670c2cc2..9dd026b5e33b30 100644
--- a/test/digest/test_digest_extend.rb
+++ b/test/digest/test_digest_extend.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'digest'
 require_relative '../lib/with_different_ofs.rb'
diff --git a/test/drb/drbtest.rb b/test/drb/drbtest.rb
index 11b542a4ee29d0..4488e1be2179a2 100644
--- a/test/drb/drbtest.rb
+++ b/test/drb/drbtest.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'drb/drb'
 require 'drb/extservm'
diff --git a/test/drb/ignore_test_drb.rb b/test/drb/ignore_test_drb.rb
index 8b946505341d8b..996a554c0fefda 100644
--- a/test/drb/ignore_test_drb.rb
+++ b/test/drb/ignore_test_drb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drbtest'
 
 module DRbTests
diff --git a/test/drb/test_acl.rb b/test/drb/test_acl.rb
index a1ee1d48c53732..c886ae2396b42d 100644
--- a/test/drb/test_acl.rb
+++ b/test/drb/test_acl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # acltest.rb - ACL unit test
 # Copyright (c) 2000 Masatoshi SEKI
 #
diff --git a/test/drb/test_drb.rb b/test/drb/test_drb.rb
index 016e62f7c6a4f3..dd2855e3b0d0c8 100644
--- a/test/drb/test_drb.rb
+++ b/test/drb/test_drb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'drbtest'
 
 module DRbTests
diff --git a/test/drb/test_drbssl.rb b/test/drb/test_drbssl.rb
index bcf5f9034acaef..1f1495356e0f57 100644
--- a/test/drb/test_drbssl.rb
+++ b/test/drb/test_drbssl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'drbtest'
 
 begin
diff --git a/test/drb/test_drbunix.rb b/test/drb/test_drbunix.rb
index c422b7a6898912..7ece2453a944c1 100644
--- a/test/drb/test_drbunix.rb
+++ b/test/drb/test_drbunix.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'drbtest'
 
 begin
diff --git a/test/drb/ut_array.rb b/test/drb/ut_array.rb
index 01599f1d89e800..d13dda3d8e500a 100644
--- a/test/drb/ut_array.rb
+++ b/test/drb/ut_array.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 
diff --git a/test/drb/ut_array_drbssl.rb b/test/drb/ut_array_drbssl.rb
index fa9afa6abd5c7a..08849ca176d2c0 100644
--- a/test/drb/ut_array_drbssl.rb
+++ b/test/drb/ut_array_drbssl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 require 'drb/ssl'
diff --git a/test/drb/ut_array_drbunix.rb b/test/drb/ut_array_drbunix.rb
index dd397907c7dcd0..b656cdaddd8476 100644
--- a/test/drb/ut_array_drbunix.rb
+++ b/test/drb/ut_array_drbunix.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 
diff --git a/test/drb/ut_drb.rb b/test/drb/ut_drb.rb
index 0dd0988a7da8b5..6a94a0fb401bcb 100644
--- a/test/drb/ut_drb.rb
+++ b/test/drb/ut_drb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 require 'timeout'
diff --git a/test/drb/ut_drb_drbssl.rb b/test/drb/ut_drb_drbssl.rb
index b6d1c1226251f8..ddaa859e7de32c 100644
--- a/test/drb/ut_drb_drbssl.rb
+++ b/test/drb/ut_drb_drbssl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "ut_drb"
 require 'drb/ssl'
 
diff --git a/test/drb/ut_drb_drbunix.rb b/test/drb/ut_drb_drbunix.rb
index c997d2469d05ae..ecf0920451a78d 100644
--- a/test/drb/ut_drb_drbunix.rb
+++ b/test/drb/ut_drb_drbunix.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "#{File.dirname(File.expand_path(__FILE__))}/ut_drb"
 
 if __FILE__ == $0
diff --git a/test/drb/ut_eq.rb b/test/drb/ut_eq.rb
index cc86158363a390..56285a384f35d5 100644
--- a/test/drb/ut_eq.rb
+++ b/test/drb/ut_eq.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 
diff --git a/test/drb/ut_eval.rb b/test/drb/ut_eval.rb
index c456790fd9f7a1..0a81b40b0efd66 100644
--- a/test/drb/ut_eval.rb
+++ b/test/drb/ut_eval.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 
diff --git a/test/drb/ut_large.rb b/test/drb/ut_large.rb
index c2fbd3e1849bb7..c00279e7cb38d1 100644
--- a/test/drb/ut_large.rb
+++ b/test/drb/ut_large.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 require 'timeout'
diff --git a/test/drb/ut_port.rb b/test/drb/ut_port.rb
index 3009db5acdd881..d317a307cc12d4 100644
--- a/test/drb/ut_port.rb
+++ b/test/drb/ut_port.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 
diff --git a/test/drb/ut_safe1.rb b/test/drb/ut_safe1.rb
index 43eb367689d787..4b16fa7d6d8eb7 100644
--- a/test/drb/ut_safe1.rb
+++ b/test/drb/ut_safe1.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'drb/drb'
 require 'drb/extserv'
 
diff --git a/test/drb/ut_timerholder.rb b/test/drb/ut_timerholder.rb
index 6c62ea7726a999..1b992d95f3b816 100644
--- a/test/drb/ut_timerholder.rb
+++ b/test/drb/ut_timerholder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'runit/testcase'
 require 'runit/cui/testrunner'
 require 'timerholder'
diff --git a/test/dtrace/dummy.rb b/test/dtrace/dummy.rb
index e85614228c9e49..932cb4e625a33e 100644
--- a/test/dtrace/dummy.rb
+++ b/test/dtrace/dummy.rb
@@ -1 +1,2 @@
+# frozen_string_literal: false
 # this is a dummy file used by test/dtrace/test_require.rb
diff --git a/test/dtrace/helper.rb b/test/dtrace/helper.rb
index f76c41b0251ad3..a479b1adb7b601 100644
--- a/test/dtrace/helper.rb
+++ b/test/dtrace/helper.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 
diff --git a/test/dtrace/test_array_create.rb b/test/dtrace/test_array_create.rb
index d849bcc0c71331..44d4657b61c721 100644
--- a/test/dtrace/test_array_create.rb
+++ b/test/dtrace/test_array_create.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_cmethod.rb b/test/dtrace/test_cmethod.rb
index 0a9107fa38a420..a0aa1b646ba46c 100644
--- a/test/dtrace/test_cmethod.rb
+++ b/test/dtrace/test_cmethod.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_function_entry.rb b/test/dtrace/test_function_entry.rb
index 74aee64b02b0d9..fc07ccc4550833 100644
--- a/test/dtrace/test_function_entry.rb
+++ b/test/dtrace/test_function_entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_gc.rb b/test/dtrace/test_gc.rb
index 2f58a110967fe3..77de7998dd0067 100644
--- a/test/dtrace/test_gc.rb
+++ b/test/dtrace/test_gc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_hash_create.rb b/test/dtrace/test_hash_create.rb
index 2cceded38f49b3..83a4d0062cfa28 100644
--- a/test/dtrace/test_hash_create.rb
+++ b/test/dtrace/test_hash_create.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_load.rb b/test/dtrace/test_load.rb
index cceb0c29259cf8..1c208bd488c1e1 100644
--- a/test/dtrace/test_load.rb
+++ b/test/dtrace/test_load.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 require 'tempfile'
 
diff --git a/test/dtrace/test_method_cache.rb b/test/dtrace/test_method_cache.rb
index d8ddf454f448d9..7ecec194b2c9e7 100644
--- a/test/dtrace/test_method_cache.rb
+++ b/test/dtrace/test_method_cache.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_object_create_start.rb b/test/dtrace/test_object_create_start.rb
index 2be961161365bc..81f8ed21104074 100644
--- a/test/dtrace/test_object_create_start.rb
+++ b/test/dtrace/test_object_create_start.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_raise.rb b/test/dtrace/test_raise.rb
index 48fdbf14d1eaa8..81e64e8c16f64b 100644
--- a/test/dtrace/test_raise.rb
+++ b/test/dtrace/test_raise.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_require.rb b/test/dtrace/test_require.rb
index 46a1d7652a6b12..9fa6c0e87c7c4a 100644
--- a/test/dtrace/test_require.rb
+++ b/test/dtrace/test_require.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_singleton_function.rb b/test/dtrace/test_singleton_function.rb
index 9e118f65b7a3e0..3698a02c93eae8 100644
--- a/test/dtrace/test_singleton_function.rb
+++ b/test/dtrace/test_singleton_function.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/dtrace/test_string.rb b/test/dtrace/test_string.rb
index 873d5ac3645ac0..407280b1fc44ce 100644
--- a/test/dtrace/test_string.rb
+++ b/test/dtrace/test_string.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module DTrace
diff --git a/test/erb/test_erb.rb b/test/erb/test_erb.rb
index 1f1253fd23f399..4e2d49a866ab17 100644
--- a/test/erb/test_erb.rb
+++ b/test/erb/test_erb.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 require 'erb'
 
diff --git a/test/erb/test_erb_command.rb b/test/erb/test_erb_command.rb
index abc8fdbe25e6d3..406b14cdb3f2b1 100644
--- a/test/erb/test_erb_command.rb
+++ b/test/erb/test_erb_command.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestErbCommand < Test::Unit::TestCase
diff --git a/test/erb/test_erb_m17n.rb b/test/erb/test_erb_m17n.rb
index f60dd103f61e38..a7840c9605d6f8 100644
--- a/test/erb/test_erb_m17n.rb
+++ b/test/erb/test_erb_m17n.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 require 'test/unit'
 require 'erb'
 
diff --git a/test/etc/test_etc.rb b/test/etc/test_etc.rb
index 5ac09a781bccb9..ec9083eb160dda 100644
--- a/test/etc/test_etc.rb
+++ b/test/etc/test_etc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "etc"
 
diff --git a/test/excludes/TestException.rb b/test/excludes/TestException.rb
index 78ee4ca1c02ee6..a992950152b060 100644
--- a/test/excludes/TestException.rb
+++ b/test/excludes/TestException.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 reason = %[\
 Because machine stack overflow can happen anywhere, even critical
 sections including external libraries, it is very neary impossible to
diff --git a/test/excludes/TestIO_Console.rb b/test/excludes/TestIO_Console.rb
index 26780c01b12e40..caf1935fecece6 100644
--- a/test/excludes/TestIO_Console.rb
+++ b/test/excludes/TestIO_Console.rb
@@ -1 +1,2 @@
+# frozen_string_literal: false
 exclude(:test_getpass, 'not portable')
diff --git a/test/excludes/TestThread.rb b/test/excludes/TestThread.rb
index 0b4050b4ebbf1b..ea73a4c0102188 100644
--- a/test/excludes/TestThread.rb
+++ b/test/excludes/TestThread.rb
@@ -1 +1,2 @@
+# frozen_string_literal: false
 exclude(/_stack_size$/, 'often too expensive')
diff --git a/test/fiddle/helper.rb b/test/fiddle/helper.rb
index 0952cc24388d88..1da3d938194e94 100644
--- a/test/fiddle/helper.rb
+++ b/test/fiddle/helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'minitest/autorun'
 require 'fiddle'
 
diff --git a/test/fiddle/test_c_struct_entry.rb b/test/fiddle/test_c_struct_entry.rb
index de5449b43da4c2..39b7aeff996c78 100644
--- a/test/fiddle/test_c_struct_entry.rb
+++ b/test/fiddle/test_c_struct_entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
   require 'fiddle/struct'
diff --git a/test/fiddle/test_c_union_entity.rb b/test/fiddle/test_c_union_entity.rb
index 165c4ecacbafaa..3c4d538ff1bbb8 100644
--- a/test/fiddle/test_c_union_entity.rb
+++ b/test/fiddle/test_c_union_entity.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
   require 'fiddle/struct'
diff --git a/test/fiddle/test_closure.rb b/test/fiddle/test_closure.rb
index 56839e7b631336..0e3574ff84eeef 100644
--- a/test/fiddle/test_closure.rb
+++ b/test/fiddle/test_closure.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
 rescue LoadError
diff --git a/test/fiddle/test_cparser.rb b/test/fiddle/test_cparser.rb
index 4d4799d8d648da..16134f5aa72319 100644
--- a/test/fiddle/test_cparser.rb
+++ b/test/fiddle/test_cparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
   require 'fiddle/cparser'
diff --git a/test/fiddle/test_fiddle.rb b/test/fiddle/test_fiddle.rb
index 4c6ab97b12e1bf..cf4839af8608bf 100644
--- a/test/fiddle/test_fiddle.rb
+++ b/test/fiddle/test_fiddle.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
 rescue LoadError
diff --git a/test/fiddle/test_func.rb b/test/fiddle/test_func.rb
index 529aaa8baf286f..5cdf90f5679f1a 100644
--- a/test/fiddle/test_func.rb
+++ b/test/fiddle/test_func.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
 rescue LoadError
diff --git a/test/fiddle/test_function.rb b/test/fiddle/test_function.rb
index 9351f961df6ed2..06d0eb2b509e42 100644
--- a/test/fiddle/test_function.rb
+++ b/test/fiddle/test_function.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
 rescue LoadError
diff --git a/test/fiddle/test_handle.rb b/test/fiddle/test_handle.rb
index 54165f00afa691..f14357c6cb68fb 100644
--- a/test/fiddle/test_handle.rb
+++ b/test/fiddle/test_handle.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
 rescue LoadError
diff --git a/test/fiddle/test_import.rb b/test/fiddle/test_import.rb
index c83f50fe447883..ba68296fd055eb 100644
--- a/test/fiddle/test_import.rb
+++ b/test/fiddle/test_import.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 begin
   require_relative 'helper'
   require 'fiddle/import'
diff --git a/test/fiddle/test_pointer.rb b/test/fiddle/test_pointer.rb
index ef54470943f6f9..ec677324eb8cb3 100644
--- a/test/fiddle/test_pointer.rb
+++ b/test/fiddle/test_pointer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require_relative 'helper'
 rescue LoadError
diff --git a/test/fileutils/clobber.rb b/test/fileutils/clobber.rb
index 9f946651bfa98e..ae416e9fa58632 100644
--- a/test/fileutils/clobber.rb
+++ b/test/fileutils/clobber.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'fileutils'
 require 'test/unit'
 require 'tmpdir'
diff --git a/test/fileutils/fileasserts.rb b/test/fileutils/fileasserts.rb
index b6067f6d848407..512d31e95f7a76 100644
--- a/test/fileutils/fileasserts.rb
+++ b/test/fileutils/fileasserts.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $Id$
 
 module Test
diff --git a/test/fileutils/test_dryrun.rb b/test/fileutils/test_dryrun.rb
index 03f6bed387b779..bc59f8d339abbf 100644
--- a/test/fileutils/test_dryrun.rb
+++ b/test/fileutils/test_dryrun.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $Id$
 
 require 'fileutils'
diff --git a/test/fileutils/test_fileutils.rb b/test/fileutils/test_fileutils.rb
index 1a6f1c5c55e7d1..f5ca9d21e2d33f 100644
--- a/test/fileutils/test_fileutils.rb
+++ b/test/fileutils/test_fileutils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $Id$
 
 require 'fileutils'
diff --git a/test/fileutils/test_nowrite.rb b/test/fileutils/test_nowrite.rb
index 946eed3b6cd54f..f331d51e46ef44 100644
--- a/test/fileutils/test_nowrite.rb
+++ b/test/fileutils/test_nowrite.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $Id$
 
 require 'fileutils'
diff --git a/test/fileutils/test_verbose.rb b/test/fileutils/test_verbose.rb
index fb069bcf14eab7..1daf9f05318854 100644
--- a/test/fileutils/test_verbose.rb
+++ b/test/fileutils/test_verbose.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $Id$
 
 require 'test/unit'
diff --git a/test/fileutils/visibility_tests.rb b/test/fileutils/visibility_tests.rb
index a1406146748066..6bb5a9fc8fe2bd 100644
--- a/test/fileutils/visibility_tests.rb
+++ b/test/fileutils/visibility_tests.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'fileutils'
 
diff --git a/test/gdbm/test_gdbm.rb b/test/gdbm/test_gdbm.rb
index 729424dec531a3..0a42da386cc180 100644
--- a/test/gdbm/test_gdbm.rb
+++ b/test/gdbm/test_gdbm.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'gdbm'
 rescue LoadError
diff --git a/test/io/console/test_io_console.rb b/test/io/console/test_io_console.rb
index ba9063e1b3357e..36619cebd54cd2 100644
--- a/test/io/console/test_io_console.rb
+++ b/test/io/console/test_io_console.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'io/console'
   require 'test/unit'
diff --git a/test/io/nonblock/test_flush.rb b/test/io/nonblock/test_flush.rb
index 70e65cceedf029..bc60cab8bf5795 100644
--- a/test/io/nonblock/test_flush.rb
+++ b/test/io/nonblock/test_flush.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 begin
diff --git a/test/io/wait/test_io_wait.rb b/test/io/wait/test_io_wait.rb
index bef4731ae53018..637917d510489c 100644
--- a/test/io/wait/test_io_wait.rb
+++ b/test/io/wait/test_io_wait.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 require 'socket'
diff --git a/test/irb/test_completion.rb b/test/irb/test_completion.rb
index eeeda1234c63a5..608c41bad9fbea 100644
--- a/test/irb/test_completion.rb
+++ b/test/irb/test_completion.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module TestIRB
diff --git a/test/irb/test_option.rb b/test/irb/test_option.rb
index a7dd663112cfa3..85ebd085ca21eb 100644
--- a/test/irb/test_option.rb
+++ b/test/irb/test_option.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module TestIRB
diff --git a/test/irb/test_raise_no_backtrace_exception.rb b/test/irb/test_raise_no_backtrace_exception.rb
index 67fb5b66ccc835..d3882a427c0422 100644
--- a/test/irb/test_raise_no_backtrace_exception.rb
+++ b/test/irb/test_raise_no_backtrace_exception.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module TestIRB
diff --git a/test/json/setup_variant.rb b/test/json/setup_variant.rb
index 2dab184bc421a8..f7fb2a1d5637c9 100644
--- a/test/json/setup_variant.rb
+++ b/test/json/setup_variant.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 case ENV['JSON']
 when 'pure'
   $:.unshift 'lib'
diff --git a/test/json/test_json.rb b/test/json/test_json.rb
index 07287eed81629a..8fe94599784ef7 100755
--- a/test/json/test_json.rb
+++ b/test/json/test_json.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
diff --git a/test/json/test_json_addition.rb b/test/json/test_json_addition.rb
index 6034a183bd8929..f2059312de871a 100644
--- a/test/json/test_json_addition.rb
+++ b/test/json/test_json_addition.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby
 # -*- coding:utf-8 -*-
+# frozen_string_literal: false
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
diff --git a/test/json/test_json_encoding.rb b/test/json/test_json_encoding.rb
index 13903cd266f707..50fb4ea2793a22 100644
--- a/test/json/test_json_encoding.rb
+++ b/test/json/test_json_encoding.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
diff --git a/test/json/test_json_fixtures.rb b/test/json/test_json_fixtures.rb
index c861439573421c..e192706d6b63ec 100644
--- a/test/json/test_json_fixtures.rb
+++ b/test/json/test_json_fixtures.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
diff --git a/test/json/test_json_generate.rb b/test/json/test_json_generate.rb
index 5da0d2f4f01a3c..50895f62476927 100644
--- a/test/json/test_json_generate.rb
+++ b/test/json/test_json_generate.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
diff --git a/test/json/test_json_generic_object.rb b/test/json/test_json_generic_object.rb
index c43c7762be9afd..e04e1a1cb3e86d 100644
--- a/test/json/test_json_generic_object.rb
+++ b/test/json/test_json_generic_object.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
diff --git a/test/json/test_json_string_matching.rb b/test/json/test_json_string_matching.rb
index c233df8c2cd28b..615823110362f6 100644
--- a/test/json/test_json_string_matching.rb
+++ b/test/json/test_json_string_matching.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
diff --git a/test/json/test_json_unicode.rb b/test/json/test_json_unicode.rb
index 8352d5c6c6a573..16234f04910b89 100644
--- a/test/json/test_json_unicode.rb
+++ b/test/json/test_json_unicode.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
diff --git a/test/lib/envutil.rb b/test/lib/envutil.rb
index 2f2ec6deb646bd..a0b907c24594c6 100644
--- a/test/lib/envutil.rb
+++ b/test/lib/envutil.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require "open3"
 require "timeout"
 require_relative "find_executable"
diff --git a/test/lib/find_executable.rb b/test/lib/find_executable.rb
index 4ba9a0533e701f..0ddd307f8cc7bc 100644
--- a/test/lib/find_executable.rb
+++ b/test/lib/find_executable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rbconfig"
 
 module EnvUtil
diff --git a/test/lib/iseq_loader_checker.rb b/test/lib/iseq_loader_checker.rb
index db9b7678c918bf..675b6580d6c526 100644
--- a/test/lib/iseq_loader_checker.rb
+++ b/test/lib/iseq_loader_checker.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 
 begin
   require '-test-/iseq_load/iseq_load'
diff --git a/test/lib/leakchecker.rb b/test/lib/leakchecker.rb
index 98a598f365796e..a9bc5813c5b317 100644
--- a/test/lib/leakchecker.rb
+++ b/test/lib/leakchecker.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class LeakChecker
   def initialize
     @fd_info = find_fds
diff --git a/test/lib/memory_status.rb b/test/lib/memory_status.rb
index b275db05e6db63..deaaeb2a1b27ce 100644
--- a/test/lib/memory_status.rb
+++ b/test/lib/memory_status.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module Memory
   keys = []
   vals = []
diff --git a/test/lib/minitest/autorun.rb b/test/lib/minitest/autorun.rb
index 88b1e0550dea5d..40640b2580dcbc 100644
--- a/test/lib/minitest/autorun.rb
+++ b/test/lib/minitest/autorun.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 begin
   require 'rubygems'
diff --git a/test/lib/minitest/benchmark.rb b/test/lib/minitest/benchmark.rb
index 5195fc01bc7a37..21f0b29d509b28 100644
--- a/test/lib/minitest/benchmark.rb
+++ b/test/lib/minitest/benchmark.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'minitest/unit'
 
diff --git a/test/lib/minitest/mock.rb b/test/lib/minitest/mock.rb
index 19acaff68e5b8c..07e88113ea614d 100644
--- a/test/lib/minitest/mock.rb
+++ b/test/lib/minitest/mock.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 class MockExpectationError < StandardError; end # :nodoc:
 
diff --git a/test/lib/minitest/unit.rb b/test/lib/minitest/unit.rb
index e67ca02cd8cc55..62f89e97e59e27 100644
--- a/test/lib/minitest/unit.rb
+++ b/test/lib/minitest/unit.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require "optparse"
 require "rbconfig"
diff --git a/test/lib/profile_test_all.rb b/test/lib/profile_test_all.rb
index 08de7bb1296d18..4496d3f780b558 100644
--- a/test/lib/profile_test_all.rb
+++ b/test/lib/profile_test_all.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # purpose:
 #  Profile memory usage of each tests.
diff --git a/test/lib/test/unit.rb b/test/lib/test/unit.rb
index d886f29c739aca..85e6d76f3d68de 100644
--- a/test/lib/test/unit.rb
+++ b/test/lib/test/unit.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   gem 'minitest', '< 5.0.0' if defined? Gem
 rescue Gem::LoadError
diff --git a/test/lib/test/unit/assertions.rb b/test/lib/test/unit/assertions.rb
index 201e24592abd41..c749384ebaf0dc 100644
--- a/test/lib/test/unit/assertions.rb
+++ b/test/lib/test/unit/assertions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'minitest/unit'
 require 'pp'
 
diff --git a/test/lib/test/unit/parallel.rb b/test/lib/test/unit/parallel.rb
index 780deda5ae3c46..6a319c3c3f7238 100644
--- a/test/lib/test/unit/parallel.rb
+++ b/test/lib/test/unit/parallel.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 $LOAD_PATH.unshift "#{File.dirname(__FILE__)}/../.."
 require 'test/unit'
 
diff --git a/test/lib/test/unit/testcase.rb b/test/lib/test/unit/testcase.rb
index d6ea4fd2b1d416..10348b5c9b4233 100644
--- a/test/lib/test/unit/testcase.rb
+++ b/test/lib/test/unit/testcase.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit/assertions'
 
 module Test
diff --git a/test/lib/tracepointchecker.rb b/test/lib/tracepointchecker.rb
index 2d56e658ff4ed3..73631d415eec51 100644
--- a/test/lib/tracepointchecker.rb
+++ b/test/lib/tracepointchecker.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module TracePointChecker
   STATE = {
     count: 0,
diff --git a/test/lib/with_different_ofs.rb b/test/lib/with_different_ofs.rb
index 76dfa6896ca261..164914f1d6c5e4 100644
--- a/test/lib/with_different_ofs.rb
+++ b/test/lib/with_different_ofs.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module DifferentOFS
   module WithDifferentOFS
     def setup
diff --git a/test/lib/zombie_hunter.rb b/test/lib/zombie_hunter.rb
index 77be4dfea85bde..8a8fba649cfa26 100644
--- a/test/lib/zombie_hunter.rb
+++ b/test/lib/zombie_hunter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module ZombieHunter
   def after_teardown
     super
diff --git a/test/logger/test_logdevice.rb b/test/logger/test_logdevice.rb
index f6dcf9a5a3cc68..8a7938984f6a86 100644
--- a/test/logger/test_logdevice.rb
+++ b/test/logger/test_logdevice.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 require 'logger'
 require 'tempfile'
diff --git a/test/logger/test_logger.rb b/test/logger/test_logger.rb
index 24a53c1f646ee7..836d3b30f43377 100644
--- a/test/logger/test_logger.rb
+++ b/test/logger/test_logger.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 require 'logger'
 require 'tempfile'
diff --git a/test/logger/test_severity.rb b/test/logger/test_severity.rb
index 045461caa2bab5..f17a3928291984 100644
--- a/test/logger/test_severity.rb
+++ b/test/logger/test_severity.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 require 'logger'
 
diff --git a/test/matrix/test_matrix.rb b/test/matrix/test_matrix.rb
index 4e4dda0ee1d678..425ec25a5249ea 100644
--- a/test/matrix/test_matrix.rb
+++ b/test/matrix/test_matrix.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'matrix'
 
diff --git a/test/matrix/test_vector.rb b/test/matrix/test_vector.rb
index 77fc68dd2b8669..72082be84c7f0a 100644
--- a/test/matrix/test_vector.rb
+++ b/test/matrix/test_vector.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'matrix'
 
diff --git a/test/minitest/metametameta.rb b/test/minitest/metametameta.rb
index 9ffbdb056993bd..a12717c8b19188 100644
--- a/test/minitest/metametameta.rb
+++ b/test/minitest/metametameta.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'tempfile'
 require 'stringio'
diff --git a/test/minitest/test_minitest_benchmark.rb b/test/minitest/test_minitest_benchmark.rb
index d04bb9a125690a..a783e684c2ddab 100644
--- a/test/minitest/test_minitest_benchmark.rb
+++ b/test/minitest/test_minitest_benchmark.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'minitest/autorun'
 require 'minitest/benchmark'
diff --git a/test/minitest/test_minitest_mock.rb b/test/minitest/test_minitest_mock.rb
index 062cda56ff5b52..0db972674c3734 100644
--- a/test/minitest/test_minitest_mock.rb
+++ b/test/minitest/test_minitest_mock.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'minitest/autorun'
 
diff --git a/test/minitest/test_minitest_unit.rb b/test/minitest/test_minitest_unit.rb
index 61bfe25ee3fbb7..315c36d416e41f 100644
--- a/test/minitest/test_minitest_unit.rb
+++ b/test/minitest/test_minitest_unit.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: false
 
 require 'pathname'
 require 'minitest/metametameta'
diff --git a/test/misc/test_ruby_mode.rb b/test/misc/test_ruby_mode.rb
index 5be01747f184eb..a91e1c254cc20a 100644
--- a/test/misc/test_ruby_mode.rb
+++ b/test/misc/test_ruby_mode.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 
diff --git a/test/mkmf/base.rb b/test/mkmf/base.rb
index d8e2a04fe76048..86bdd29286e2e7 100644
--- a/test/mkmf/base.rb
+++ b/test/mkmf/base.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 $extmk = true
 
 require 'test/unit'
diff --git a/test/mkmf/test_config.rb b/test/mkmf/test_config.rb
index 7bf537e69336b7..07ed6414151eb9 100644
--- a/test/mkmf/test_config.rb
+++ b/test/mkmf/test_config.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 $extmk = true
 
 require 'test/unit'
diff --git a/test/mkmf/test_constant.rb b/test/mkmf/test_constant.rb
index fd1f940c44590f..f5a87a1caad401 100644
--- a/test/mkmf/test_constant.rb
+++ b/test/mkmf/test_constant.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 
 class TestMkmf
diff --git a/test/mkmf/test_convertible.rb b/test/mkmf/test_convertible.rb
index eec2d12c667fb0..1baf8928424901 100644
--- a/test/mkmf/test_convertible.rb
+++ b/test/mkmf/test_convertible.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 
 class TestMkmf
diff --git a/test/mkmf/test_find_executable.rb b/test/mkmf/test_find_executable.rb
index fe45ef2d1ced78..d2b460bd005a68 100644
--- a/test/mkmf/test_find_executable.rb
+++ b/test/mkmf/test_find_executable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 
 class TestMkmf
diff --git a/test/mkmf/test_flags.rb b/test/mkmf/test_flags.rb
index e49d474dc904f4..69a1084608ed9c 100644
--- a/test/mkmf/test_flags.rb
+++ b/test/mkmf/test_flags.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 
 class TestMkmf
diff --git a/test/mkmf/test_framework.rb b/test/mkmf/test_framework.rb
index 70ea8c3327c54d..ae05b0cffc354d 100644
--- a/test/mkmf/test_framework.rb
+++ b/test/mkmf/test_framework.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 
 class TestMkmf
diff --git a/test/mkmf/test_have_func.rb b/test/mkmf/test_have_func.rb
index 8049ffba182c87..5f76b72122ad95 100644
--- a/test/mkmf/test_have_func.rb
+++ b/test/mkmf/test_have_func.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 require 'tempfile'
 
diff --git a/test/mkmf/test_have_library.rb b/test/mkmf/test_have_library.rb
index bf17b85f618bf8..bb9ce6972d1731 100644
--- a/test/mkmf/test_have_library.rb
+++ b/test/mkmf/test_have_library.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 require 'tempfile'
 
diff --git a/test/mkmf/test_have_macro.rb b/test/mkmf/test_have_macro.rb
index 43c4029f702068..ebc564809708b3 100644
--- a/test/mkmf/test_have_macro.rb
+++ b/test/mkmf/test_have_macro.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 require 'tempfile'
 
diff --git a/test/mkmf/test_libs.rb b/test/mkmf/test_libs.rb
index 27674dfd26ed2d..bb65e4de902fff 100644
--- a/test/mkmf/test_libs.rb
+++ b/test/mkmf/test_libs.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 
 class TestMkmf
diff --git a/test/mkmf/test_signedness.rb b/test/mkmf/test_signedness.rb
index 8d58073698420d..589dcb56e8e185 100644
--- a/test/mkmf/test_signedness.rb
+++ b/test/mkmf/test_signedness.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 
 class TestMkmf
diff --git a/test/mkmf/test_sizeof.rb b/test/mkmf/test_sizeof.rb
index c0144226d5c124..742c3d64541441 100644
--- a/test/mkmf/test_sizeof.rb
+++ b/test/mkmf/test_sizeof.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'base'
 
 class TestMkmf
diff --git a/test/monitor/test_monitor.rb b/test/monitor/test_monitor.rb
index 088bf28a37f226..66c3e833caa2ef 100644
--- a/test/monitor/test_monitor.rb
+++ b/test/monitor/test_monitor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "monitor"
 require "thread"
 
diff --git a/test/net/http/test_buffered_io.rb b/test/net/http/test_buffered_io.rb
index e24e7c1ed91aae..8c299ead032e6f 100644
--- a/test/net/http/test_buffered_io.rb
+++ b/test/net/http/test_buffered_io.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'net/http'
 require 'stringio'
diff --git a/test/net/http/test_http.rb b/test/net/http/test_http.rb
index 714e576cc11d81..d8983e91cd3666 100644
--- a/test/net/http/test_http.rb
+++ b/test/net/http/test_http.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 require 'net/http'
 require 'stringio'
diff --git a/test/net/http/test_http_request.rb b/test/net/http/test_http_request.rb
index 1dcb847c3f8491..35c935ac58c3a8 100644
--- a/test/net/http/test_http_request.rb
+++ b/test/net/http/test_http_request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'net/http'
 require 'test/unit'
 require 'stringio'
diff --git a/test/net/http/test_httpheader.rb b/test/net/http/test_httpheader.rb
index 224d8bb9a9da61..2f3a0f115741a3 100644
--- a/test/net/http/test_httpheader.rb
+++ b/test/net/http/test_httpheader.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'net/http'
 require 'test/unit'
 
diff --git a/test/net/http/test_httpresponse.rb b/test/net/http/test_httpresponse.rb
index a86020581c1898..eb1a792e878293 100644
--- a/test/net/http/test_httpresponse.rb
+++ b/test/net/http/test_httpresponse.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'net/http'
 require 'test/unit'
 require 'stringio'
diff --git a/test/net/http/test_httpresponses.rb b/test/net/http/test_httpresponses.rb
index bf7fbeef1158de..b389e163cf815c 100644
--- a/test/net/http/test_httpresponses.rb
+++ b/test/net/http/test_httpresponses.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'net/http'
 require 'test/unit'
 
diff --git a/test/net/http/test_https.rb b/test/net/http/test_https.rb
index 8177d9451ffbbf..dfdb221d7e82e0 100644
--- a/test/net/http/test_https.rb
+++ b/test/net/http/test_https.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 begin
   require 'net/https'
diff --git a/test/net/http/test_https_proxy.rb b/test/net/http/test_https_proxy.rb
index 1c8503b7e157b3..f833f1a1e3fc11 100644
--- a/test/net/http/test_https_proxy.rb
+++ b/test/net/http/test_https_proxy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'net/https'
 rescue LoadError
diff --git a/test/net/http/utils.rb b/test/net/http/utils.rb
index dcd94693c2082c..8d0ecd6020fa3f 100644
--- a/test/net/http/utils.rb
+++ b/test/net/http/utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'webrick'
 begin
   require "webrick/https"
diff --git a/test/net/pop/test_pop.rb b/test/net/pop/test_pop.rb
index 7aa65a44325410..f06ccb445251f1 100644
--- a/test/net/pop/test_pop.rb
+++ b/test/net/pop/test_pop.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'net/pop'
 require 'test/unit'
 require 'digest/md5'
diff --git a/test/net/protocol/test_protocol.rb b/test/net/protocol/test_protocol.rb
index 4453422552e9c1..0161fbc3a094a5 100644
--- a/test/net/protocol/test_protocol.rb
+++ b/test/net/protocol/test_protocol.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "net/protocol"
 require "stringio"
diff --git a/test/net/smtp/test_response.rb b/test/net/smtp/test_response.rb
index cfd90b18ecc444..79ac1d2d32ba47 100644
--- a/test/net/smtp/test_response.rb
+++ b/test/net/smtp/test_response.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'net/smtp'
 require 'test/unit'
 
diff --git a/test/net/smtp/test_smtp.rb b/test/net/smtp/test_smtp.rb
index d8bb0c192c5fa5..0edb3419d56e83 100644
--- a/test/net/smtp/test_smtp.rb
+++ b/test/net/smtp/test_smtp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'net/smtp'
 require 'stringio'
 require 'test/unit'
diff --git a/test/net/smtp/test_ssl_socket.rb b/test/net/smtp/test_ssl_socket.rb
index ff229b5ad02ec4..20792190c893cd 100644
--- a/test/net/smtp/test_ssl_socket.rb
+++ b/test/net/smtp/test_ssl_socket.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'net/smtp'
 require 'test/unit'
 
diff --git a/test/nkf/test_kconv.rb b/test/nkf/test_kconv.rb
index 09c0ce803a570e..de09bcd4ae9560 100644
--- a/test/nkf/test_kconv.rb
+++ b/test/nkf/test_kconv.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'kconv'
 
diff --git a/test/nkf/test_nkf.rb b/test/nkf/test_nkf.rb
index 7329e75f125529..eb51bf8e7d5f71 100644
--- a/test/nkf/test_nkf.rb
+++ b/test/nkf/test_nkf.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'nkf'
 
diff --git a/test/objspace/test_objspace.rb b/test/objspace/test_objspace.rb
index de719944197a54..f3ea88f6e4cf8f 100644
--- a/test/objspace/test_objspace.rb
+++ b/test/objspace/test_objspace.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "objspace"
 
diff --git a/test/openssl/test_asn1.rb b/test/openssl/test_asn1.rb
index 8955d727167fb0..fd2118d808d252 100644
--- a/test/openssl/test_asn1.rb
+++ b/test/openssl/test_asn1.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 class  OpenSSL::TestASN1 < Test::Unit::TestCase
diff --git a/test/openssl/test_bn.rb b/test/openssl/test_bn.rb
index 667cb2964e977b..848d1feb4371e3 100644
--- a/test/openssl/test_bn.rb
+++ b/test/openssl/test_bn.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_buffering.rb b/test/openssl/test_buffering.rb
index 0ca645998e38ab..fe07b46a5e2226 100644
--- a/test/openssl/test_buffering.rb
+++ b/test/openssl/test_buffering.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 require 'stringio'
 
diff --git a/test/openssl/test_cipher.rb b/test/openssl/test_cipher.rb
index 6f92c381cf82cc..89c176f4de4100 100644
--- a/test/openssl/test_cipher.rb
+++ b/test/openssl/test_cipher.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_config.rb b/test/openssl/test_config.rb
index 62f9fabce20b09..8f5bdb215054c5 100644
--- a/test/openssl/test_config.rb
+++ b/test/openssl/test_config.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 class OpenSSL::TestConfig < Test::Unit::TestCase
diff --git a/test/openssl/test_digest.rb b/test/openssl/test_digest.rb
index 5390225f36c8bd..e206ca0283ecfa 100644
--- a/test/openssl/test_digest.rb
+++ b/test/openssl/test_digest.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_engine.rb b/test/openssl/test_engine.rb
index a7264d0eeb890d..3521de63961475 100644
--- a/test/openssl/test_engine.rb
+++ b/test/openssl/test_engine.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 class OpenSSL::TestEngine < Test::Unit::TestCase
diff --git a/test/openssl/test_fips.rb b/test/openssl/test_fips.rb
index 6e4ac6d3457c8a..33769c9388f97b 100644
--- a/test/openssl/test_fips.rb
+++ b/test/openssl/test_fips.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_hmac.rb b/test/openssl/test_hmac.rb
index f709ebd69bc098..135d26f02c76c1 100644
--- a/test/openssl/test_hmac.rb
+++ b/test/openssl/test_hmac.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 
 require_relative 'utils'
 
diff --git a/test/openssl/test_ns_spki.rb b/test/openssl/test_ns_spki.rb
index ab07bfbebb3adc..4f6e6f59e79106 100644
--- a/test/openssl/test_ns_spki.rb
+++ b/test/openssl/test_ns_spki.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_ocsp.rb b/test/openssl/test_ocsp.rb
index af727d8ecdb4d2..1a969fd767f342 100644
--- a/test/openssl/test_ocsp.rb
+++ b/test/openssl/test_ocsp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_pair.rb b/test/openssl/test_pair.rb
index 33ec55549252a8..06ed3836ca98b2 100644
--- a/test/openssl/test_pair.rb
+++ b/test/openssl/test_pair.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_partial_record_read.rb b/test/openssl/test_partial_record_read.rb
index 1899a300df1a7f..71e644a0395816 100644
--- a/test/openssl/test_partial_record_read.rb
+++ b/test/openssl/test_partial_record_read.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_pkcs12.rb b/test/openssl/test_pkcs12.rb
index c44cee00ed747d..ba07d7678983ad 100644
--- a/test/openssl/test_pkcs12.rb
+++ b/test/openssl/test_pkcs12.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_pkcs5.rb b/test/openssl/test_pkcs5.rb
index 5e85dde955beb8..f38fd716b7627c 100644
--- a/test/openssl/test_pkcs5.rb
+++ b/test/openssl/test_pkcs5.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 class OpenSSL::TestPKCS5 < Test::Unit::TestCase
diff --git a/test/openssl/test_pkcs7.rb b/test/openssl/test_pkcs7.rb
index 47bd4f31337ef7..ce99db50b17070 100644
--- a/test/openssl/test_pkcs7.rb
+++ b/test/openssl/test_pkcs7.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_pkey_dh.rb b/test/openssl/test_pkey_dh.rb
index 040d0309143a6a..9ef4025bee3fd1 100644
--- a/test/openssl/test_pkey_dh.rb
+++ b/test/openssl/test_pkey_dh.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_pkey_dsa.rb b/test/openssl/test_pkey_dsa.rb
index e4ea1b5bd71813..eb3e4f1c65e6e5 100644
--- a/test/openssl/test_pkey_dsa.rb
+++ b/test/openssl/test_pkey_dsa.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 require 'base64'
 
diff --git a/test/openssl/test_pkey_ec.rb b/test/openssl/test_pkey_ec.rb
index 1693ace01fb0fa..fe128fd4556baf 100644
--- a/test/openssl/test_pkey_ec.rb
+++ b/test/openssl/test_pkey_ec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils) && defined?(OpenSSL::PKey::EC)
diff --git a/test/openssl/test_pkey_rsa.rb b/test/openssl/test_pkey_rsa.rb
index ea042c27857923..165b1ec98eb9f9 100644
--- a/test/openssl/test_pkey_rsa.rb
+++ b/test/openssl/test_pkey_rsa.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 require 'base64'
 
diff --git a/test/openssl/test_random.rb b/test/openssl/test_random.rb
index e4242acf18247b..8c69d5431c4008 100644
--- a/test/openssl/test_random.rb
+++ b/test/openssl/test_random.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require "openssl"
 rescue LoadError
diff --git a/test/openssl/test_ssl.rb b/test/openssl/test_ssl.rb
index 5682bf5081fed6..58fcc0802aa23e 100644
--- a/test/openssl/test_ssl.rb
+++ b/test/openssl/test_ssl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_ssl_session.rb b/test/openssl/test_ssl_session.rb
index 28d268e76b13b3..3294aa7f80d551 100644
--- a/test/openssl/test_ssl_session.rb
+++ b/test/openssl/test_ssl_session.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_x509cert.rb b/test/openssl/test_x509cert.rb
index 783677a4324f41..72cb9e6095f2fa 100644
--- a/test/openssl/test_x509cert.rb
+++ b/test/openssl/test_x509cert.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_x509crl.rb b/test/openssl/test_x509crl.rb
index 9dc1b1cd14b465..7994ddeaf9068d 100644
--- a/test/openssl/test_x509crl.rb
+++ b/test/openssl/test_x509crl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_x509ext.rb b/test/openssl/test_x509ext.rb
index 29e9f1dc44c59d..e6d49bb679e4d1 100644
--- a/test/openssl/test_x509ext.rb
+++ b/test/openssl/test_x509ext.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_x509name.rb b/test/openssl/test_x509name.rb
index a92af534929059..56e79879cfcb59 100644
--- a/test/openssl/test_x509name.rb
+++ b/test/openssl/test_x509name.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require_relative 'utils'
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_x509req.rb b/test/openssl/test_x509req.rb
index 27040cb7bf3287..f1bf18465f8244 100644
--- a/test/openssl/test_x509req.rb
+++ b/test/openssl/test_x509req.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/test_x509store.rb b/test/openssl/test_x509store.rb
index f3e144fc51be7f..9964cc8fc47a10 100644
--- a/test/openssl/test_x509store.rb
+++ b/test/openssl/test_x509store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "utils"
 
 if defined?(OpenSSL::TestUtils)
diff --git a/test/openssl/utils.rb b/test/openssl/utils.rb
index bd936beed70def..0802c1ba998754 100644
--- a/test/openssl/utils.rb
+++ b/test/openssl/utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require "openssl"
 
diff --git a/test/optparse/test_acceptable.rb b/test/optparse/test_acceptable.rb
index ee8479cc1e9461..0c7590bae3fa03 100644
--- a/test/optparse/test_acceptable.rb
+++ b/test/optparse/test_acceptable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'test_optparse'
 
 class TestOptionParser::Acceptable < TestOptionParser
diff --git a/test/optparse/test_autoconf.rb b/test/optparse/test_autoconf.rb
index cb9c9386096c83..4b3616f81668be 100644
--- a/test/optparse/test_autoconf.rb
+++ b/test/optparse/test_autoconf.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'optparse/ac'
 
diff --git a/test/optparse/test_bash_completion.rb b/test/optparse/test_bash_completion.rb
index baeb6d9882c867..714fd35cff61b9 100644
--- a/test/optparse/test_bash_completion.rb
+++ b/test/optparse/test_bash_completion.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'optparse'
 
diff --git a/test/optparse/test_getopts.rb b/test/optparse/test_getopts.rb
index ae22f68184f1f8..3711e6f2698cae 100644
--- a/test/optparse/test_getopts.rb
+++ b/test/optparse/test_getopts.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'optparse'
 
diff --git a/test/optparse/test_noarg.rb b/test/optparse/test_noarg.rb
index 3e6ed42f91ea93..8f9be29ab869ba 100644
--- a/test/optparse/test_noarg.rb
+++ b/test/optparse/test_noarg.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'test_optparse'
 
 module TestOptionParser::NoArg
diff --git a/test/optparse/test_optarg.rb b/test/optparse/test_optarg.rb
index 3114b80fc5bbf0..b7436fb74ce3b4 100644
--- a/test/optparse/test_optarg.rb
+++ b/test/optparse/test_optarg.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'test_optparse'
 
 class TestOptionParser::OptArg < TestOptionParser
diff --git a/test/optparse/test_optparse.rb b/test/optparse/test_optparse.rb
index e85a2ef5869182..f17f8ee8956e64 100644
--- a/test/optparse/test_optparse.rb
+++ b/test/optparse/test_optparse.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'optparse'
 
diff --git a/test/optparse/test_placearg.rb b/test/optparse/test_placearg.rb
index 0bbd1a007e06ae..90b2b97a632128 100644
--- a/test/optparse/test_placearg.rb
+++ b/test/optparse/test_placearg.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'test_optparse'
 
 class TestOptionParser::PlaceArg < TestOptionParser
diff --git a/test/optparse/test_reqarg.rb b/test/optparse/test_reqarg.rb
index 397da4a5935d45..1904f4615492e4 100644
--- a/test/optparse/test_reqarg.rb
+++ b/test/optparse/test_reqarg.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'test_optparse'
 
 module TestOptionParser::ReqArg
diff --git a/test/optparse/test_summary.rb b/test/optparse/test_summary.rb
index 54fd194bbd7231..b743aa00c1d94a 100644
--- a/test/optparse/test_summary.rb
+++ b/test/optparse/test_summary.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'test_optparse'
 
 class TestOptionParser::SummaryTest < TestOptionParser
diff --git a/test/optparse/test_zsh_completion.rb b/test/optparse/test_zsh_completion.rb
index 7e5ba713840e99..1bc6c7f0bb3fe2 100644
--- a/test/optparse/test_zsh_completion.rb
+++ b/test/optparse/test_zsh_completion.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'optparse'
 
diff --git a/test/ostruct/test_ostruct.rb b/test/ostruct/test_ostruct.rb
index b098992bc9df2e..8c122b94a742d0 100644
--- a/test/ostruct/test_ostruct.rb
+++ b/test/ostruct/test_ostruct.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'ostruct'
 
diff --git a/test/psych/handlers/test_recorder.rb b/test/psych/handlers/test_recorder.rb
index 96b8eac1fc6dde..17c7c6d0a02b84 100644
--- a/test/psych/handlers/test_recorder.rb
+++ b/test/psych/handlers/test_recorder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/helper'
 require 'psych/handlers/recorder'
 
diff --git a/test/psych/helper.rb b/test/psych/helper.rb
index 3bbb45932012cb..498cdf8b090ba2 100644
--- a/test/psych/helper.rb
+++ b/test/psych/helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'minitest/autorun'
 require 'stringio'
 require 'tempfile'
diff --git a/test/psych/json/test_stream.rb b/test/psych/json/test_stream.rb
index b0c33e6a2aa9d1..519c114b29354e 100644
--- a/test/psych/json/test_stream.rb
+++ b/test/psych/json/test_stream.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/helper'
 
 module Psych
diff --git a/test/psych/nodes/test_enumerable.rb b/test/psych/nodes/test_enumerable.rb
index 19cf94bd513fd4..2f4e1f3bd0faae 100644
--- a/test/psych/nodes/test_enumerable.rb
+++ b/test/psych/nodes/test_enumerable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/helper'
 
 module Psych
diff --git a/test/psych/test_alias_and_anchor.rb b/test/psych/test_alias_and_anchor.rb
index 9e2c24013d3acc..ed009605ca4fbc 100644
--- a/test/psych/test_alias_and_anchor.rb
+++ b/test/psych/test_alias_and_anchor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 class ObjectWithInstanceVariables
diff --git a/test/psych/test_array.rb b/test/psych/test_array.rb
index 960ffd71d8e39e..f1e71fb16c851b 100644
--- a/test/psych/test_array.rb
+++ b/test/psych/test_array.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_boolean.rb b/test/psych/test_boolean.rb
index b656f4f90e81d6..b2803a6550290b 100644
--- a/test/psych/test_boolean.rb
+++ b/test/psych/test_boolean.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_class.rb b/test/psych/test_class.rb
index c7f964cc6d2ebd..4e1fd4a1d6961b 100644
--- a/test/psych/test_class.rb
+++ b/test/psych/test_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_coder.rb b/test/psych/test_coder.rb
index e3213e2faac950..e578d55f2d073f 100644
--- a/test/psych/test_coder.rb
+++ b/test/psych/test_coder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_date_time.rb b/test/psych/test_date_time.rb
index 72150ad7db43c9..433fbf3d2658d6 100644
--- a/test/psych/test_date_time.rb
+++ b/test/psych/test_date_time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 require 'date'
 
diff --git a/test/psych/test_deprecated.rb b/test/psych/test_deprecated.rb
index fd2d3299e30477..a806f6b9726fa0 100644
--- a/test/psych/test_deprecated.rb
+++ b/test/psych/test_deprecated.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_document.rb b/test/psych/test_document.rb
index bd77d60084f5f0..97de2e15ec3993 100644
--- a/test/psych/test_document.rb
+++ b/test/psych/test_document.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_emitter.rb b/test/psych/test_emitter.rb
index b19501932b43e9..54b9b356e82ffb 100644
--- a/test/psych/test_emitter.rb
+++ b/test/psych/test_emitter.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 
 require_relative 'helper'
 
diff --git a/test/psych/test_encoding.rb b/test/psych/test_encoding.rb
index 544337d4c0a8fa..13ca5dbc741eee 100644
--- a/test/psych/test_encoding.rb
+++ b/test/psych/test_encoding.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 
 require_relative 'helper'
 
diff --git a/test/psych/test_exception.rb b/test/psych/test_exception.rb
index 30dfb24f3b3e1c..85fa78f5df4c58 100644
--- a/test/psych/test_exception.rb
+++ b/test/psych/test_exception.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_hash.rb b/test/psych/test_hash.rb
index e2a312901a6399..b449ce49e375a4 100644
--- a/test/psych/test_hash.rb
+++ b/test/psych/test_hash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_json_tree.rb b/test/psych/test_json_tree.rb
index a23fc1ac8f3a07..8bb850b1388110 100644
--- a/test/psych/test_json_tree.rb
+++ b/test/psych/test_json_tree.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_marshalable.rb b/test/psych/test_marshalable.rb
index 7df74ee846bfd5..544947a521b269 100644
--- a/test/psych/test_marshalable.rb
+++ b/test/psych/test_marshalable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 require 'delegate'
 
diff --git a/test/psych/test_merge_keys.rb b/test/psych/test_merge_keys.rb
index 1620a6a4e3dfd2..76245ca7b53fe7 100644
--- a/test/psych/test_merge_keys.rb
+++ b/test/psych/test_merge_keys.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_nil.rb b/test/psych/test_nil.rb
index 3dbf56279ad76a..3d4fa88eaa49e9 100644
--- a/test/psych/test_nil.rb
+++ b/test/psych/test_nil.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_null.rb b/test/psych/test_null.rb
index 17255504433042..d8ccb7056fda10 100644
--- a/test/psych/test_null.rb
+++ b/test/psych/test_null.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_numeric.rb b/test/psych/test_numeric.rb
index 5378b4aaad034c..9d8b74f7caa90e 100644
--- a/test/psych/test_numeric.rb
+++ b/test/psych/test_numeric.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 require 'bigdecimal'
 
diff --git a/test/psych/test_object.rb b/test/psych/test_object.rb
index 5e3ce8294fed09..ed1ccd9bf89b90 100644
--- a/test/psych/test_object.rb
+++ b/test/psych/test_object.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_object_references.rb b/test/psych/test_object_references.rb
index 273b466b0cdb2f..1300bfc1db5573 100644
--- a/test/psych/test_object_references.rb
+++ b/test/psych/test_object_references.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_omap.rb b/test/psych/test_omap.rb
index 36edc26c49f47b..80791aa9187e95 100644
--- a/test/psych/test_omap.rb
+++ b/test/psych/test_omap.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_parser.rb b/test/psych/test_parser.rb
index 0abe0dd398d2bf..26aba0543b9d70 100644
--- a/test/psych/test_parser.rb
+++ b/test/psych/test_parser.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 require_relative 'helper'
 
diff --git a/test/psych/test_psych.rb b/test/psych/test_psych.rb
index 05a93438bc1870..7de9e07fdcf332 100644
--- a/test/psych/test_psych.rb
+++ b/test/psych/test_psych.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 require 'stringio'
diff --git a/test/psych/test_safe_load.rb b/test/psych/test_safe_load.rb
index dd299c0ebf403d..b69c54c1999f9c 100644
--- a/test/psych/test_safe_load.rb
+++ b/test/psych/test_safe_load.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/helper'
 
 module Psych
diff --git a/test/psych/test_scalar.rb b/test/psych/test_scalar.rb
index e6b76975a6ae48..4353ec33fa7f67 100644
--- a/test/psych/test_scalar.rb
+++ b/test/psych/test_scalar.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 
 require_relative 'helper'
 
diff --git a/test/psych/test_scalar_scanner.rb b/test/psych/test_scalar_scanner.rb
index e8e423cb053db9..7ad18c557bcd72 100644
--- a/test/psych/test_scalar_scanner.rb
+++ b/test/psych/test_scalar_scanner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 require 'date'
 
diff --git a/test/psych/test_serialize_subclasses.rb b/test/psych/test_serialize_subclasses.rb
index f597b7a05159b9..be209edf2f35af 100644
--- a/test/psych/test_serialize_subclasses.rb
+++ b/test/psych/test_serialize_subclasses.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_set.rb b/test/psych/test_set.rb
index 921fe2284f4022..0eb999cb2f0706 100644
--- a/test/psych/test_set.rb
+++ b/test/psych/test_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_stream.rb b/test/psych/test_stream.rb
index 7e41178e34f2b5..1b054289eabf64 100644
--- a/test/psych/test_stream.rb
+++ b/test/psych/test_stream.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_string.rb b/test/psych/test_string.rb
index a8ae55cabe846b..51aef408584553 100644
--- a/test/psych/test_string.rb
+++ b/test/psych/test_string.rb
@@ -1,4 +1,5 @@
 # encoding: UTF-8
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_struct.rb b/test/psych/test_struct.rb
index 8c7f2513ce4ab0..b7968d31890e57 100644
--- a/test/psych/test_struct.rb
+++ b/test/psych/test_struct.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 class PsychStructWithIvar < Struct.new(:foo)
diff --git a/test/psych/test_symbol.rb b/test/psych/test_symbol.rb
index 558a67288614af..a98881cf4b646f 100644
--- a/test/psych/test_symbol.rb
+++ b/test/psych/test_symbol.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_tainted.rb b/test/psych/test_tainted.rb
index 37fc5b2b803987..870583323dd886 100644
--- a/test/psych/test_tainted.rb
+++ b/test/psych/test_tainted.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_to_yaml_properties.rb b/test/psych/test_to_yaml_properties.rb
index 724aab4f0eb035..8a29b6a9b946a9 100644
--- a/test/psych/test_to_yaml_properties.rb
+++ b/test/psych/test_to_yaml_properties.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_tree_builder.rb b/test/psych/test_tree_builder.rb
index 7ad3ddd8a04408..09f1ee30c998b3 100644
--- a/test/psych/test_tree_builder.rb
+++ b/test/psych/test_tree_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 
 module Psych
diff --git a/test/psych/test_yaml.rb b/test/psych/test_yaml.rb
index e6281753a5051a..f8e9e2f955117a 100644
--- a/test/psych/test_yaml.rb
+++ b/test/psych/test_yaml.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii; mode: ruby; ruby-indent-level: 4; tab-width: 4 -*-
+# frozen_string_literal: false
 #												vim:sw=4:ts=4
 # $Id$
 #
diff --git a/test/psych/test_yamldbm.rb b/test/psych/test_yamldbm.rb
index 62c88b753eb0b7..71ee04f86311ba 100644
--- a/test/psych/test_yamldbm.rb
+++ b/test/psych/test_yamldbm.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 require 'tmpdir'
 
diff --git a/test/psych/test_yamlstore.rb b/test/psych/test_yamlstore.rb
index 94f1330d37ab04..a9ce652ced329b 100644
--- a/test/psych/test_yamlstore.rb
+++ b/test/psych/test_yamlstore.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'helper'
 require 'yaml/store'
 require 'tmpdir'
diff --git a/test/psych/visitors/test_depth_first.rb b/test/psych/visitors/test_depth_first.rb
index 837c8e8c117aca..8072c26b5797a1 100644
--- a/test/psych/visitors/test_depth_first.rb
+++ b/test/psych/visitors/test_depth_first.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/helper'
 
 module Psych
diff --git a/test/psych/visitors/test_emitter.rb b/test/psych/visitors/test_emitter.rb
index 780c9536931dc4..9317855bbb3022 100644
--- a/test/psych/visitors/test_emitter.rb
+++ b/test/psych/visitors/test_emitter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/helper'
 
 module Psych
diff --git a/test/psych/visitors/test_to_ruby.rb b/test/psych/visitors/test_to_ruby.rb
index 19e5365244d556..8878ea22b24ddd 100644
--- a/test/psych/visitors/test_to_ruby.rb
+++ b/test/psych/visitors/test_to_ruby.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'psych/helper'
 
 module Psych
diff --git a/test/psych/visitors/test_yaml_tree.rb b/test/psych/visitors/test_yaml_tree.rb
index 40702bce796f89..b3890bcd724564 100644
--- a/test/psych/visitors/test_yaml_tree.rb
+++ b/test/psych/visitors/test_yaml_tree.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'psych/helper'
 
 module Psych
diff --git a/test/rdoc/test_rdoc_alias.rb b/test/rdoc/test_rdoc_alias.rb
index ff499af96286d1..fa0ab0f3668eb6 100644
--- a/test/rdoc/test_rdoc_alias.rb
+++ b/test/rdoc/test_rdoc_alias.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocAlias < XrefTestCase
diff --git a/test/rdoc/test_rdoc_any_method.rb b/test/rdoc/test_rdoc_any_method.rb
index 90305807f8be7b..fdbb62efa6f2ae 100644
--- a/test/rdoc/test_rdoc_any_method.rb
+++ b/test/rdoc/test_rdoc_any_method.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocAnyMethod < XrefTestCase
diff --git a/test/rdoc/test_rdoc_attr.rb b/test/rdoc/test_rdoc_attr.rb
index a4922df06c83c8..e4062d18074442 100644
--- a/test/rdoc/test_rdoc_attr.rb
+++ b/test/rdoc/test_rdoc_attr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocAttr < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_class_module.rb b/test/rdoc/test_rdoc_class_module.rb
index 0e06587dc633f2..7cbbcbcc5265fb 100644
--- a/test/rdoc/test_rdoc_class_module.rb
+++ b/test/rdoc/test_rdoc_class_module.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocClassModule < XrefTestCase
diff --git a/test/rdoc/test_rdoc_code_object.rb b/test/rdoc/test_rdoc_code_object.rb
index 2fb6ac23a524db..74b88557e0cb5e 100644
--- a/test/rdoc/test_rdoc_code_object.rb
+++ b/test/rdoc/test_rdoc_code_object.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 
 require File.expand_path '../xref_test_case', __FILE__
 
diff --git a/test/rdoc/test_rdoc_comment.rb b/test/rdoc/test_rdoc_comment.rb
index 2a1318b66cfcd4..178c579ea72409 100644
--- a/test/rdoc/test_rdoc_comment.rb
+++ b/test/rdoc/test_rdoc_comment.rb
@@ -1,4 +1,5 @@
 # coding: us-ascii
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_constant.rb b/test/rdoc/test_rdoc_constant.rb
index 171963d8e4eb3e..c43aa7dc2bd276 100644
--- a/test/rdoc/test_rdoc_constant.rb
+++ b/test/rdoc/test_rdoc_constant.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocConstant < XrefTestCase
diff --git a/test/rdoc/test_rdoc_context.rb b/test/rdoc/test_rdoc_context.rb
index c981cf3b1158fc..c619c6cacbd8ff 100644
--- a/test/rdoc/test_rdoc_context.rb
+++ b/test/rdoc/test_rdoc_context.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocContext < XrefTestCase
diff --git a/test/rdoc/test_rdoc_context_section.rb b/test/rdoc/test_rdoc_context_section.rb
index b8f8c7f756c92c..bd82d191b68b41 100644
--- a/test/rdoc/test_rdoc_context_section.rb
+++ b/test/rdoc/test_rdoc_context_section.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocContextSection < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_cross_reference.rb b/test/rdoc/test_rdoc_cross_reference.rb
index 99fc224d88a7c8..c39d6ad3563315 100644
--- a/test/rdoc/test_rdoc_cross_reference.rb
+++ b/test/rdoc/test_rdoc_cross_reference.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocCrossReference < XrefTestCase
diff --git a/test/rdoc/test_rdoc_encoding.rb b/test/rdoc/test_rdoc_encoding.rb
index 7ec39f8a9c26c6..313ede2bdec817 100644
--- a/test/rdoc/test_rdoc_encoding.rb
+++ b/test/rdoc/test_rdoc_encoding.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_extend.rb b/test/rdoc/test_rdoc_extend.rb
index 149931549dd44c..bc50a657ac50cb 100644
--- a/test/rdoc/test_rdoc_extend.rb
+++ b/test/rdoc/test_rdoc_extend.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocExtend < XrefTestCase
diff --git a/test/rdoc/test_rdoc_generator_darkfish.rb b/test/rdoc/test_rdoc_generator_darkfish.rb
index fc77e4b10501fe..894acbd4f282f5 100644
--- a/test/rdoc/test_rdoc_generator_darkfish.rb
+++ b/test/rdoc/test_rdoc_generator_darkfish.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocGeneratorDarkfish < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_generator_json_index.rb b/test/rdoc/test_rdoc_generator_json_index.rb
index 9283fd9b768258..13e7850a242b2d 100644
--- a/test/rdoc/test_rdoc_generator_json_index.rb
+++ b/test/rdoc/test_rdoc_generator_json_index.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_generator_markup.rb b/test/rdoc/test_rdoc_generator_markup.rb
index 5f8a45bd0e47fa..d546c2f87fe012 100644
--- a/test/rdoc/test_rdoc_generator_markup.rb
+++ b/test/rdoc/test_rdoc_generator_markup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocGeneratorMarkup < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_generator_pot.rb b/test/rdoc/test_rdoc_generator_pot.rb
index d028ce71deb82b..3f1bee70c951cc 100644
--- a/test/rdoc/test_rdoc_generator_pot.rb
+++ b/test/rdoc/test_rdoc_generator_pot.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocGeneratorPOT < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_generator_pot_po.rb b/test/rdoc/test_rdoc_generator_pot_po.rb
index fae7f7ed6e3404..ae60ff004e9f5f 100644
--- a/test/rdoc/test_rdoc_generator_pot_po.rb
+++ b/test/rdoc/test_rdoc_generator_pot_po.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocGeneratorPOTPO < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_generator_pot_po_entry.rb b/test/rdoc/test_rdoc_generator_pot_po_entry.rb
index 8620d98bf84820..36b85df864fd5b 100644
--- a/test/rdoc/test_rdoc_generator_pot_po_entry.rb
+++ b/test/rdoc/test_rdoc_generator_pot_po_entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocGeneratorPOTPOEntry < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_generator_ri.rb b/test/rdoc/test_rdoc_generator_ri.rb
index f8ac97337ddb4b..1e18e13b103d81 100644
--- a/test/rdoc/test_rdoc_generator_ri.rb
+++ b/test/rdoc/test_rdoc_generator_ri.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocGeneratorRI < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_i18n_locale.rb b/test/rdoc/test_rdoc_i18n_locale.rb
index 69de88a9f2289f..e9dce78472896b 100644
--- a/test/rdoc/test_rdoc_i18n_locale.rb
+++ b/test/rdoc/test_rdoc_i18n_locale.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocI18nLocale < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_i18n_text.rb b/test/rdoc/test_rdoc_i18n_text.rb
index c47f03c1af2fa9..61df1939697a89 100644
--- a/test/rdoc/test_rdoc_i18n_text.rb
+++ b/test/rdoc/test_rdoc_i18n_text.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocI18nText < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_include.rb b/test/rdoc/test_rdoc_include.rb
index 464a6980182741..6a34f5d4b894b2 100644
--- a/test/rdoc/test_rdoc_include.rb
+++ b/test/rdoc/test_rdoc_include.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocInclude < XrefTestCase
diff --git a/test/rdoc/test_rdoc_markdown.rb b/test/rdoc/test_rdoc_markdown.rb
index ea5dc73387b0fa..6c7bf4ae3268c9 100644
--- a/test/rdoc/test_rdoc_markdown.rb
+++ b/test/rdoc/test_rdoc_markdown.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 require 'rdoc/markup/block_quote'
diff --git a/test/rdoc/test_rdoc_markdown_test.rb b/test/rdoc/test_rdoc_markdown_test.rb
index d464cba263ccb9..0d880e0a7c69bf 100644
--- a/test/rdoc/test_rdoc_markdown_test.rb
+++ b/test/rdoc/test_rdoc_markdown_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'minitest/autorun'
 require 'pp'
diff --git a/test/rdoc/test_rdoc_markup.rb b/test/rdoc/test_rdoc_markup.rb
index 5c28a2c6e6a406..ad13211f7bf327 100644
--- a/test/rdoc/test_rdoc_markup.rb
+++ b/test/rdoc/test_rdoc_markup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkup < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_attribute_manager.rb b/test/rdoc/test_rdoc_markup_attribute_manager.rb
index 6a085fe7f53297..c0f7666a01735e 100644
--- a/test/rdoc/test_rdoc_markup_attribute_manager.rb
+++ b/test/rdoc/test_rdoc_markup_attribute_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupAttributeManager < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_attributes.rb b/test/rdoc/test_rdoc_markup_attributes.rb
index 636e0cca68233b..077b6a547454f2 100644
--- a/test/rdoc/test_rdoc_markup_attributes.rb
+++ b/test/rdoc/test_rdoc_markup_attributes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupAttributes < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_document.rb b/test/rdoc/test_rdoc_markup_document.rb
index 718ae6d4c40e1c..e5a61daea5df2d 100644
--- a/test/rdoc/test_rdoc_markup_document.rb
+++ b/test/rdoc/test_rdoc_markup_document.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupDocument < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_formatter.rb b/test/rdoc/test_rdoc_markup_formatter.rb
index d01a42fca6ca71..02a6844a3ad46b 100644
--- a/test/rdoc/test_rdoc_markup_formatter.rb
+++ b/test/rdoc/test_rdoc_markup_formatter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupFormatter < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_hard_break.rb b/test/rdoc/test_rdoc_markup_hard_break.rb
index b9f7873160b2b8..5d2d3596462212 100644
--- a/test/rdoc/test_rdoc_markup_hard_break.rb
+++ b/test/rdoc/test_rdoc_markup_hard_break.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupHardBreak < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_heading.rb b/test/rdoc/test_rdoc_markup_heading.rb
index 26d4b5bffc6884..463df7ef43bf5d 100644
--- a/test/rdoc/test_rdoc_markup_heading.rb
+++ b/test/rdoc/test_rdoc_markup_heading.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupHeading < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_include.rb b/test/rdoc/test_rdoc_markup_include.rb
index 37a5b320e944b4..e72a0ac1bbcb2e 100644
--- a/test/rdoc/test_rdoc_markup_include.rb
+++ b/test/rdoc/test_rdoc_markup_include.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupInclude < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_indented_paragraph.rb b/test/rdoc/test_rdoc_markup_indented_paragraph.rb
index d8dd795e5b98c5..efcd840453dfe8 100644
--- a/test/rdoc/test_rdoc_markup_indented_paragraph.rb
+++ b/test/rdoc/test_rdoc_markup_indented_paragraph.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupIndentedParagraph < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_paragraph.rb b/test/rdoc/test_rdoc_markup_paragraph.rb
index 8de1c3cff552e5..6da6658c6f461e 100644
--- a/test/rdoc/test_rdoc_markup_paragraph.rb
+++ b/test/rdoc/test_rdoc_markup_paragraph.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupParagraph < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_parser.rb b/test/rdoc/test_rdoc_markup_parser.rb
index d27fb42f9affab..e9986553c02cfd 100644
--- a/test/rdoc/test_rdoc_markup_parser.rb
+++ b/test/rdoc/test_rdoc_markup_parser.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_markup_pre_process.rb b/test/rdoc/test_rdoc_markup_pre_process.rb
index 7cbe29c5a99bfe..8bc474a8fc9e20 100644
--- a/test/rdoc/test_rdoc_markup_pre_process.rb
+++ b/test/rdoc/test_rdoc_markup_pre_process.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_markup_raw.rb b/test/rdoc/test_rdoc_markup_raw.rb
index 43bfe0c3b11b76..1453333b9ecca5 100644
--- a/test/rdoc/test_rdoc_markup_raw.rb
+++ b/test/rdoc/test_rdoc_markup_raw.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupRaw < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_to_ansi.rb b/test/rdoc/test_rdoc_markup_to_ansi.rb
index 5afaf9435005ce..8bd49271c1c6ee 100644
--- a/test/rdoc/test_rdoc_markup_to_ansi.rb
+++ b/test/rdoc/test_rdoc_markup_to_ansi.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToAnsi < RDoc::Markup::TextFormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_bs.rb b/test/rdoc/test_rdoc_markup_to_bs.rb
index f2e6352b69ef1f..33d274a97f2d66 100644
--- a/test/rdoc/test_rdoc_markup_to_bs.rb
+++ b/test/rdoc/test_rdoc_markup_to_bs.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToBs < RDoc::Markup::TextFormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_html.rb b/test/rdoc/test_rdoc_markup_to_html.rb
index dbbd2871886654..1c7c879980b90a 100644
--- a/test/rdoc/test_rdoc_markup_to_html.rb
+++ b/test/rdoc/test_rdoc_markup_to_html.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToHtml < RDoc::Markup::FormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_html_crossref.rb b/test/rdoc/test_rdoc_markup_to_html_crossref.rb
index 872daea1dcd071..39a482740f3ff6 100644
--- a/test/rdoc/test_rdoc_markup_to_html_crossref.rb
+++ b/test/rdoc/test_rdoc_markup_to_html_crossref.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocMarkupToHtmlCrossref < XrefTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_html_snippet.rb b/test/rdoc/test_rdoc_markup_to_html_snippet.rb
index f861db18499d53..11bcd526be8167 100644
--- a/test/rdoc/test_rdoc_markup_to_html_snippet.rb
+++ b/test/rdoc/test_rdoc_markup_to_html_snippet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToHtmlSnippet < RDoc::Markup::FormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_joined_paragraph.rb b/test/rdoc/test_rdoc_markup_to_joined_paragraph.rb
index 148edb177205b5..414b7d3732c911 100644
--- a/test/rdoc/test_rdoc_markup_to_joined_paragraph.rb
+++ b/test/rdoc/test_rdoc_markup_to_joined_paragraph.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToJoinedParagraph < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_markup_to_label.rb b/test/rdoc/test_rdoc_markup_to_label.rb
index d8cc3650693e38..35df69c2ac96a0 100644
--- a/test/rdoc/test_rdoc_markup_to_label.rb
+++ b/test/rdoc/test_rdoc_markup_to_label.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToLabel < RDoc::Markup::FormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_markdown.rb b/test/rdoc/test_rdoc_markup_to_markdown.rb
index 442bb19e9c76fe..a72f30ee01db22 100644
--- a/test/rdoc/test_rdoc_markup_to_markdown.rb
+++ b/test/rdoc/test_rdoc_markup_to_markdown.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToMarkdown < RDoc::Markup::TextFormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_rdoc.rb b/test/rdoc/test_rdoc_markup_to_rdoc.rb
index 4b60d0133e808e..0dce0a0d5ae525 100644
--- a/test/rdoc/test_rdoc_markup_to_rdoc.rb
+++ b/test/rdoc/test_rdoc_markup_to_rdoc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToRDoc < RDoc::Markup::TextFormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_table_of_contents.rb b/test/rdoc/test_rdoc_markup_to_table_of_contents.rb
index ba17b845a70c82..acfa80794871d1 100644
--- a/test/rdoc/test_rdoc_markup_to_table_of_contents.rb
+++ b/test/rdoc/test_rdoc_markup_to_table_of_contents.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToTableOfContents < RDoc::Markup::FormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_to_tt_only.rb b/test/rdoc/test_rdoc_markup_to_tt_only.rb
index 2e950dd1b0a244..a7918c90ab8326 100644
--- a/test/rdoc/test_rdoc_markup_to_tt_only.rb
+++ b/test/rdoc/test_rdoc_markup_to_tt_only.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupToTtOnly < RDoc::Markup::FormatterTestCase
diff --git a/test/rdoc/test_rdoc_markup_verbatim.rb b/test/rdoc/test_rdoc_markup_verbatim.rb
index 781d52849ab4b0..6fdf8fde28ddc9 100644
--- a/test/rdoc/test_rdoc_markup_verbatim.rb
+++ b/test/rdoc/test_rdoc_markup_verbatim.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocMarkupVerbatim < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_method_attr.rb b/test/rdoc/test_rdoc_method_attr.rb
index e93e81cee4dff9..70f129ef320574 100644
--- a/test/rdoc/test_rdoc_method_attr.rb
+++ b/test/rdoc/test_rdoc_method_attr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocMethodAttr < XrefTestCase
diff --git a/test/rdoc/test_rdoc_normal_class.rb b/test/rdoc/test_rdoc_normal_class.rb
index ab31a8dd12331b..9153bdc839e54f 100644
--- a/test/rdoc/test_rdoc_normal_class.rb
+++ b/test/rdoc/test_rdoc_normal_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocNormalClass < XrefTestCase
diff --git a/test/rdoc/test_rdoc_normal_module.rb b/test/rdoc/test_rdoc_normal_module.rb
index 1944564596d833..d92a72e7bf157d 100644
--- a/test/rdoc/test_rdoc_normal_module.rb
+++ b/test/rdoc/test_rdoc_normal_module.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocNormalModule < XrefTestCase
diff --git a/test/rdoc/test_rdoc_options.rb b/test/rdoc/test_rdoc_options.rb
index 67053e3e334ab3..5d79432f94a218 100644
--- a/test/rdoc/test_rdoc_options.rb
+++ b/test/rdoc/test_rdoc_options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocOptions < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_parser.rb b/test/rdoc/test_rdoc_parser.rb
index 34d4486cb1ff43..ee2865ce020442 100644
--- a/test/rdoc/test_rdoc_parser.rb
+++ b/test/rdoc/test_rdoc_parser.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_parser_c.rb b/test/rdoc/test_rdoc_parser_c.rb
index 71ffce5f9ab65f..fdc303e3e57325 100644
--- a/test/rdoc/test_rdoc_parser_c.rb
+++ b/test/rdoc/test_rdoc_parser_c.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 =begin
diff --git a/test/rdoc/test_rdoc_parser_changelog.rb b/test/rdoc/test_rdoc_parser_changelog.rb
index 4d83983092ba97..0135d26d8763ec 100644
--- a/test/rdoc/test_rdoc_parser_changelog.rb
+++ b/test/rdoc/test_rdoc_parser_changelog.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocParserChangeLog < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_parser_markdown.rb b/test/rdoc/test_rdoc_parser_markdown.rb
index b17e14432b0d8f..a8a84029460ed3 100644
--- a/test/rdoc/test_rdoc_parser_markdown.rb
+++ b/test/rdoc/test_rdoc_parser_markdown.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocParserMarkdown < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_parser_rd.rb b/test/rdoc/test_rdoc_parser_rd.rb
index 9be0d7d31cb1bf..481d190ffe7733 100644
--- a/test/rdoc/test_rdoc_parser_rd.rb
+++ b/test/rdoc/test_rdoc_parser_rd.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocParserRd < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_parser_ruby.rb b/test/rdoc/test_rdoc_parser_ruby.rb
index 8750433ff1ca71..2befa87542ac28 100644
--- a/test/rdoc/test_rdoc_parser_ruby.rb
+++ b/test/rdoc/test_rdoc_parser_ruby.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_parser_simple.rb b/test/rdoc/test_rdoc_parser_simple.rb
index d45a99358a541d..0e2cf0d9a905a4 100644
--- a/test/rdoc/test_rdoc_parser_simple.rb
+++ b/test/rdoc/test_rdoc_parser_simple.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocParserSimple < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_rd.rb b/test/rdoc/test_rdoc_rd.rb
index d917a63661e801..938c5569f9b60f 100644
--- a/test/rdoc/test_rdoc_rd.rb
+++ b/test/rdoc/test_rdoc_rd.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocRd < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_rd_block_parser.rb b/test/rdoc/test_rdoc_rd_block_parser.rb
index 956f3d28224d57..7afa9a03dd865c 100644
--- a/test/rdoc/test_rdoc_rd_block_parser.rb
+++ b/test/rdoc/test_rdoc_rd_block_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocRdBlockParser < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_rd_inline.rb b/test/rdoc/test_rdoc_rd_inline.rb
index d601ecca1a42ff..d4448e4397c71b 100644
--- a/test/rdoc/test_rdoc_rd_inline.rb
+++ b/test/rdoc/test_rdoc_rd_inline.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocRdInline < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_rd_inline_parser.rb b/test/rdoc/test_rdoc_rd_inline_parser.rb
index e4a765b4fb0b72..eb022b240f1fda 100644
--- a/test/rdoc/test_rdoc_rd_inline_parser.rb
+++ b/test/rdoc/test_rdoc_rd_inline_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocRdInlineParser < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_rdoc.rb b/test/rdoc/test_rdoc_rdoc.rb
index 230c18fde27479..793580de86cbf6 100644
--- a/test/rdoc/test_rdoc_rdoc.rb
+++ b/test/rdoc/test_rdoc_rdoc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocRDoc < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_require.rb b/test/rdoc/test_rdoc_require.rb
index b7995aff7b0161..cbedf5c8a4bc53 100644
--- a/test/rdoc/test_rdoc_require.rb
+++ b/test/rdoc/test_rdoc_require.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocRequire < XrefTestCase
diff --git a/test/rdoc/test_rdoc_ri_driver.rb b/test/rdoc/test_rdoc_ri_driver.rb
index d0987a01c32e4f..cba7bedb2a560d 100644
--- a/test/rdoc/test_rdoc_ri_driver.rb
+++ b/test/rdoc/test_rdoc_ri_driver.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocRIDriver < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_ri_paths.rb b/test/rdoc/test_rdoc_ri_paths.rb
index e377b0b1d00fb7..06968b5510d659 100644
--- a/test/rdoc/test_rdoc_ri_paths.rb
+++ b/test/rdoc/test_rdoc_ri_paths.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocRIPaths < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_ruby_lex.rb b/test/rdoc/test_rdoc_ruby_lex.rb
index 8871b4f4121049..6356fa28948ce9 100644
--- a/test/rdoc/test_rdoc_ruby_lex.rb
+++ b/test/rdoc/test_rdoc_ruby_lex.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_ruby_token.rb b/test/rdoc/test_rdoc_ruby_token.rb
index ed8c8275ba10d8..4638606ef3df26 100644
--- a/test/rdoc/test_rdoc_ruby_token.rb
+++ b/test/rdoc/test_rdoc_ruby_token.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocRubyToken < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_rubygems_hook.rb b/test/rdoc/test_rdoc_rubygems_hook.rb
index 960afc9ed4e82f..9ab481cbd41613 100644
--- a/test/rdoc/test_rdoc_rubygems_hook.rb
+++ b/test/rdoc/test_rdoc_rubygems_hook.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/test_case'
 require 'rdoc/rubygems_hook'
diff --git a/test/rdoc/test_rdoc_servlet.rb b/test/rdoc/test_rdoc_servlet.rb
index 9edd176cc4dcf3..1ea0de7a267206 100644
--- a/test/rdoc/test_rdoc_servlet.rb
+++ b/test/rdoc/test_rdoc_servlet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocServlet < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_single_class.rb b/test/rdoc/test_rdoc_single_class.rb
index e368b3d6fdd4ca..85a99d2229ce9d 100644
--- a/test/rdoc/test_rdoc_single_class.rb
+++ b/test/rdoc/test_rdoc_single_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocSingleClass < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_stats.rb b/test/rdoc/test_rdoc_stats.rb
index cd37c29fce9bda..34e14177835b99 100644
--- a/test/rdoc/test_rdoc_stats.rb
+++ b/test/rdoc/test_rdoc_stats.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocStats < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_store.rb b/test/rdoc/test_rdoc_store.rb
index bd565e7149606f..c1717549c66ff6 100644
--- a/test/rdoc/test_rdoc_store.rb
+++ b/test/rdoc/test_rdoc_store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocStore < XrefTestCase
diff --git a/test/rdoc/test_rdoc_task.rb b/test/rdoc/test_rdoc_task.rb
index 610684e540bdd9..bb5d2ae1344ee7 100644
--- a/test/rdoc/test_rdoc_task.rb
+++ b/test/rdoc/test_rdoc_task.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 begin
   require 'rake'
diff --git a/test/rdoc/test_rdoc_text.rb b/test/rdoc/test_rdoc_text.rb
index a69989d15d6ab5..3945b6e718a3ec 100644
--- a/test/rdoc/test_rdoc_text.rb
+++ b/test/rdoc/test_rdoc_text.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 require 'rdoc/test_case'
 
diff --git a/test/rdoc/test_rdoc_token_stream.rb b/test/rdoc/test_rdoc_token_stream.rb
index 3c1a225c25f5ce..5ed7b1d1a9bc9c 100644
--- a/test/rdoc/test_rdoc_token_stream.rb
+++ b/test/rdoc/test_rdoc_token_stream.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocTokenStream < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_tom_doc.rb b/test/rdoc/test_rdoc_tom_doc.rb
index 63d3a5e79ea6f8..7076edfa721fc2 100644
--- a/test/rdoc/test_rdoc_tom_doc.rb
+++ b/test/rdoc/test_rdoc_tom_doc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rdoc/test_case'
 
 class TestRDocTomDoc < RDoc::TestCase
diff --git a/test/rdoc/test_rdoc_top_level.rb b/test/rdoc/test_rdoc_top_level.rb
index f3ee6a4784fa97..b8145e3f9dbefb 100644
--- a/test/rdoc/test_rdoc_top_level.rb
+++ b/test/rdoc/test_rdoc_top_level.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require File.expand_path '../xref_test_case', __FILE__
 
 class TestRDocTopLevel < XrefTestCase
diff --git a/test/rdoc/xref_data.rb b/test/rdoc/xref_data.rb
index 4525a293abd009..5d3f6a9a556b4e 100644
--- a/test/rdoc/xref_data.rb
+++ b/test/rdoc/xref_data.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 XREF_DATA = <<-XREF_DATA
 class C1
 
diff --git a/test/rdoc/xref_test_case.rb b/test/rdoc/xref_test_case.rb
index a56fa71268c911..c0b3ae5abd946f 100644
--- a/test/rdoc/xref_test_case.rb
+++ b/test/rdoc/xref_test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ENV['RDOC_TEST'] = 'yes'
 
 require 'rdoc'
diff --git a/test/readline/test_readline.rb b/test/readline/test_readline.rb
index 89d72b560ff655..eae9518fb33afb 100644
--- a/test/readline/test_readline.rb
+++ b/test/readline/test_readline.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require "readline"
 rescue LoadError
diff --git a/test/readline/test_readline_history.rb b/test/readline/test_readline_history.rb
index 4bcd7b3b252be4..a9a324fb9e7871 100644
--- a/test/readline/test_readline_history.rb
+++ b/test/readline/test_readline_history.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require "readline"
 =begin
diff --git a/test/resolv/test_addr.rb b/test/resolv/test_addr.rb
index e06c3c2a4cef79..4a2df5bfcab03d 100644
--- a/test/resolv/test_addr.rb
+++ b/test/resolv/test_addr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'resolv'
 require 'socket'
diff --git a/test/resolv/test_dns.rb b/test/resolv/test_dns.rb
index 9f993ba96a8877..338130e64f69fc 100644
--- a/test/resolv/test_dns.rb
+++ b/test/resolv/test_dns.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'resolv'
 require 'socket'
diff --git a/test/resolv/test_resource.rb b/test/resolv/test_resource.rb
index 7ec17e33e79f7c..8045bbc6ee975c 100644
--- a/test/resolv/test_resource.rb
+++ b/test/resolv/test_resource.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'resolv'
 
diff --git a/test/rexml/listener.rb b/test/rexml/listener.rb
index 81c9e8822cb6a9..6bede03c599ef4 100644
--- a/test/rexml/listener.rb
+++ b/test/rexml/listener.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Listener
   attr_reader :ts, :te
   attr_reader :normalize
diff --git a/test/rexml/parse/test_document_type_declaration.rb b/test/rexml/parse/test_document_type_declaration.rb
index 59fe5611554e6e..80f70888fb5605 100644
--- a/test/rexml/parse/test_document_type_declaration.rb
+++ b/test/rexml/parse/test_document_type_declaration.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "rexml/document"
 
diff --git a/test/rexml/parse/test_notation_declaration.rb b/test/rexml/parse/test_notation_declaration.rb
index 0a4e737abf2b1f..0d29f0d81f179f 100644
--- a/test/rexml/parse/test_notation_declaration.rb
+++ b/test/rexml/parse/test_notation_declaration.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'rexml/document'
 
diff --git a/test/rexml/parser/test_sax2.rb b/test/rexml/parser/test_sax2.rb
index dba5eab033b4f4..91d135f5f73b63 100644
--- a/test/rexml/parser/test_sax2.rb
+++ b/test/rexml/parser/test_sax2.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "rexml/parsers/sax2parser"
 require "rexml/sax2listener"
diff --git a/test/rexml/parser/test_tree.rb b/test/rexml/parser/test_tree.rb
index fa010f6975b68e..7ab0addca1b470 100644
--- a/test/rexml/parser/test_tree.rb
+++ b/test/rexml/parser/test_tree.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "rexml/document"
 require "rexml/parsers/treeparser"
diff --git a/test/rexml/parser/test_ultra_light.rb b/test/rexml/parser/test_ultra_light.rb
index 4960fc16dccda7..c48a13d3115c4b 100644
--- a/test/rexml/parser/test_ultra_light.rb
+++ b/test/rexml/parser/test_ultra_light.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "rexml/parsers/ultralightparser"
 
diff --git a/test/rexml/rexml_test_utils.rb b/test/rexml/rexml_test_utils.rb
index 57fe65ca734e93..7c59629e538da0 100644
--- a/test/rexml/rexml_test_utils.rb
+++ b/test/rexml/rexml_test_utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 module REXMLTestUtils
   def fixture_path(*components)
diff --git a/test/rexml/test_attributes.rb b/test/rexml/test_attributes.rb
index aea1d8857ce815..d6f566bdf84c46 100644
--- a/test/rexml/test_attributes.rb
+++ b/test/rexml/test_attributes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit/testcase'
 require 'rexml/document'
 
diff --git a/test/rexml/test_attributes_mixin.rb b/test/rexml/test_attributes_mixin.rb
index 17cca4efc3b285..3a9f54eefd7e42 100644
--- a/test/rexml/test_attributes_mixin.rb
+++ b/test/rexml/test_attributes_mixin.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'rexml/document'
 
diff --git a/test/rexml/test_changing_encoding.rb b/test/rexml/test_changing_encoding.rb
index 9471ad13adac2b..a2dc07254a9197 100644
--- a/test/rexml/test_changing_encoding.rb
+++ b/test/rexml/test_changing_encoding.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 
 require 'rexml/encoding'
 
diff --git a/test/rexml/test_comment.rb b/test/rexml/test_comment.rb
index d5e78a5cde55a1..0af2f5ca76c8e2 100644
--- a/test/rexml/test_comment.rb
+++ b/test/rexml/test_comment.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit/testcase"
 
 require 'rexml/document'
diff --git a/test/rexml/test_contrib.rb b/test/rexml/test_contrib.rb
index fa84ebef3aaad8..8462b3c23fc839 100644
--- a/test/rexml/test_contrib.rb
+++ b/test/rexml/test_contrib.rb
@@ -1,4 +1,5 @@
 # coding: binary
+# frozen_string_literal: false
 
 require_relative "rexml_test_utils"
 
diff --git a/test/rexml/test_core.rb b/test/rexml/test_core.rb
index 97aada9104a5b4..f4eba0bbb3e9f5 100644
--- a/test/rexml/test_core.rb
+++ b/test/rexml/test_core.rb
@@ -1,4 +1,5 @@
 # coding: binary
+# frozen_string_literal: false
 
 require_relative "rexml_test_utils"
 
diff --git a/test/rexml/test_doctype.rb b/test/rexml/test_doctype.rb
index 0b3ea119296d10..91de05b05fb99e 100644
--- a/test/rexml/test_doctype.rb
+++ b/test/rexml/test_doctype.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'rexml/document'
 
diff --git a/test/rexml/test_document.rb b/test/rexml/test_document.rb
index 46cd6f7dbd385f..c0faae4ae0fc4a 100644
--- a/test/rexml/test_document.rb
+++ b/test/rexml/test_document.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 
 require "rexml/document"
 require "test/unit"
diff --git a/test/rexml/test_elements.rb b/test/rexml/test_elements.rb
index f253a75daf00b8..a850e622092c4e 100644
--- a/test/rexml/test_elements.rb
+++ b/test/rexml/test_elements.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit/testcase'
 require 'rexml/document'
 
diff --git a/test/rexml/test_encoding.rb b/test/rexml/test_encoding.rb
index 058fb974b29c1b..919db131f06f01 100644
--- a/test/rexml/test_encoding.rb
+++ b/test/rexml/test_encoding.rb
@@ -1,4 +1,5 @@
 # coding: binary
+# frozen_string_literal: false
 
 require_relative "rexml_test_utils"
 
diff --git a/test/rexml/test_entity.rb b/test/rexml/test_entity.rb
index bef1bd6c01a92b..6dc6637074e503 100644
--- a/test/rexml/test_entity.rb
+++ b/test/rexml/test_entity.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit/testcase"
 
 require 'rexml/document'
diff --git a/test/rexml/test_functions.rb b/test/rexml/test_functions.rb
index bf501ff0c233e8..5ac823dd8f8a83 100644
--- a/test/rexml/test_functions.rb
+++ b/test/rexml/test_functions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit/testcase"
 
 require "rexml/document"
diff --git a/test/rexml/test_functions_number.rb b/test/rexml/test_functions_number.rb
index 0b5ec92f6cd9ed..84ec5c7ba79a10 100644
--- a/test/rexml/test_functions_number.rb
+++ b/test/rexml/test_functions_number.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rexml/document'
 require 'test/unit'
 require 'rexml/functions'
diff --git a/test/rexml/test_jaxen.rb b/test/rexml/test_jaxen.rb
index 1eec73f3e03828..aa9e2998abdc25 100644
--- a/test/rexml/test_jaxen.rb
+++ b/test/rexml/test_jaxen.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'rexml_test_utils'
 
 require "rexml/document"
diff --git a/test/rexml/test_light.rb b/test/rexml/test_light.rb
index b775eb79e9e403..99bd9cac3f55a3 100644
--- a/test/rexml/test_light.rb
+++ b/test/rexml/test_light.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rexml_test_utils"
 require "rexml/light/node"
 require "rexml/parsers/lightparser"
diff --git a/test/rexml/test_lightparser.rb b/test/rexml/test_lightparser.rb
index f8212dcd2ea8a1..1aeac072dd50e0 100644
--- a/test/rexml/test_lightparser.rb
+++ b/test/rexml/test_lightparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'rexml_test_utils'
 require 'rexml/parsers/lightparser'
 
diff --git a/test/rexml/test_listener.rb b/test/rexml/test_listener.rb
index 309e827880b790..322d368be8c23b 100644
--- a/test/rexml/test_listener.rb
+++ b/test/rexml/test_listener.rb
@@ -1,4 +1,5 @@
 # coding: binary
+# frozen_string_literal: false
 
 require_relative 'rexml_test_utils'
 
diff --git a/test/rexml/test_martin_fowler.rb b/test/rexml/test_martin_fowler.rb
index 26db1108694942..da685a80ec1dc9 100644
--- a/test/rexml/test_martin_fowler.rb
+++ b/test/rexml/test_martin_fowler.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'rexml/document'
 
diff --git a/test/rexml/test_namespace.rb b/test/rexml/test_namespace.rb
index f5cd294568e90a..90e1d369458965 100644
--- a/test/rexml/test_namespace.rb
+++ b/test/rexml/test_namespace.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rexml_test_utils"
 
 require "rexml/document"
diff --git a/test/rexml/test_order.rb b/test/rexml/test_order.rb
index 0e84961b37407a..807d9faa960ba9 100644
--- a/test/rexml/test_order.rb
+++ b/test/rexml/test_order.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'rexml_test_utils'
 require 'rexml/document'
 begin
diff --git a/test/rexml/test_preceding_sibling.rb b/test/rexml/test_preceding_sibling.rb
index 54fdd5b22ecc97..d89a1e1c90ef4e 100644
--- a/test/rexml/test_preceding_sibling.rb
+++ b/test/rexml/test_preceding_sibling.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # ISSUE 32
 require 'test/unit'
 require 'rexml/document'
diff --git a/test/rexml/test_pullparser.rb b/test/rexml/test_pullparser.rb
index db336a16e58e9a..31b5b74bd673c4 100644
--- a/test/rexml/test_pullparser.rb
+++ b/test/rexml/test_pullparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit/testcase"
 
 require 'rexml/parsers/pullparser'
diff --git a/test/rexml/test_rexml_issuezilla.rb b/test/rexml/test_rexml_issuezilla.rb
index bb634663d58f1e..1c54c9d53d666c 100644
--- a/test/rexml/test_rexml_issuezilla.rb
+++ b/test/rexml/test_rexml_issuezilla.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative 'rexml_test_utils'
 require 'rexml/document'
 
diff --git a/test/rexml/test_sax.rb b/test/rexml/test_sax.rb
index 2d37ec9dfbd825..00539f0d4c6306 100644
--- a/test/rexml/test_sax.rb
+++ b/test/rexml/test_sax.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rexml_test_utils"
 require 'rexml/sax2listener'
 require 'rexml/parsers/sax2parser'
diff --git a/test/rexml/test_stream.rb b/test/rexml/test_stream.rb
index 3164d91c9194bb..d7ceedc70e8a0d 100644
--- a/test/rexml/test_stream.rb
+++ b/test/rexml/test_stream.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit/testcase"
 require "rexml/document"
 require 'rexml/streamlistener'
diff --git a/test/rexml/test_text.rb b/test/rexml/test_text.rb
index 52ee11ef78abf2..3f8036eee34cba 100644
--- a/test/rexml/test_text.rb
+++ b/test/rexml/test_text.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/text"
 
 module REXMLTests
diff --git a/test/rexml/test_ticket_80.rb b/test/rexml/test_ticket_80.rb
index ffeece5692502b..ab6a57efaf283d 100644
--- a/test/rexml/test_ticket_80.rb
+++ b/test/rexml/test_ticket_80.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #------------------------------------------------------------------------------
 # file: rexml_test.rb
 # desc: test's REXML's XML/XPath implementation
diff --git a/test/rexml/test_validation_rng.rb b/test/rexml/test_validation_rng.rb
index 8989fe2cbf9b26..b5b50450e0bc42 100644
--- a/test/rexml/test_validation_rng.rb
+++ b/test/rexml/test_validation_rng.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit/testcase"
 
 require "rexml/document"
diff --git a/test/rexml/test_xml_declaration.rb b/test/rexml/test_xml_declaration.rb
index a96d40c5428382..a4d97c41d0085d 100644
--- a/test/rexml/test_xml_declaration.rb
+++ b/test/rexml/test_xml_declaration.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #
 #  Created by Henrik Mårtensson on 2007-02-18.
 #  Copyright (c) 2007. All rights reserved.
diff --git a/test/rexml/xpath/test_attribute.rb b/test/rexml/xpath/test_attribute.rb
index 95af4de3999902..9304db4e0d8b4b 100644
--- a/test/rexml/xpath/test_attribute.rb
+++ b/test/rexml/xpath/test_attribute.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'rexml/document'
 
diff --git a/test/rexml/xpath/test_axis_preceding_sibling.rb b/test/rexml/xpath/test_axis_preceding_sibling.rb
index 273180772aed82..5842c6bc50e585 100644
--- a/test/rexml/xpath/test_axis_preceding_sibling.rb
+++ b/test/rexml/xpath/test_axis_preceding_sibling.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit/testcase"
 require "rexml/document"
 
diff --git a/test/rexml/xpath/test_base.rb b/test/rexml/xpath/test_base.rb
index a57ba632c416e9..5079fdd75a87cf 100644
--- a/test/rexml/xpath/test_base.rb
+++ b/test/rexml/xpath/test_base.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "../rexml_test_utils"
 
 require "rexml/document"
diff --git a/test/rexml/xpath/test_node.rb b/test/rexml/xpath/test_node.rb
index aec2de1cfe96db..e0e958e70fa159 100644
--- a/test/rexml/xpath/test_node.rb
+++ b/test/rexml/xpath/test_node.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 
 require_relative "../rexml_test_utils"
 
diff --git a/test/rexml/xpath/test_predicate.rb b/test/rexml/xpath/test_predicate.rb
index 287e131c54134c..ce1aaa324bcd05 100644
--- a/test/rexml/xpath/test_predicate.rb
+++ b/test/rexml/xpath/test_predicate.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit/testcase"
 require "rexml/document"
 require "rexml/xpath"
diff --git a/test/rexml/xpath/test_text.rb b/test/rexml/xpath/test_text.rb
index 46aba3c2efa16c..03afe9667ca918 100644
--- a/test/rexml/xpath/test_text.rb
+++ b/test/rexml/xpath/test_text.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'rexml/document'
 require 'rexml/element'
diff --git a/test/rinda/test_rinda.rb b/test/rinda/test_rinda.rb
index e0b92e690c01ee..07de61438a8f17 100644
--- a/test/rinda/test_rinda.rb
+++ b/test/rinda/test_rinda.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 require 'drb/drb'
diff --git a/test/rinda/test_tuplebag.rb b/test/rinda/test_tuplebag.rb
index 3e30127f0f0c58..ab17ca047cff30 100644
--- a/test/rinda/test_tuplebag.rb
+++ b/test/rinda/test_tuplebag.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'rinda/tuplespace'
 
diff --git a/test/ripper/dummyparser.rb b/test/ripper/dummyparser.rb
index 35c08b52bb0136..3c196d9a23ded0 100644
--- a/test/ripper/dummyparser.rb
+++ b/test/ripper/dummyparser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # dummyparser.rb
 #
diff --git a/test/ripper/test_files.rb b/test/ripper/test_files.rb
index 5541a09368e175..7b5fa1dc6ce9d0 100644
--- a/test/ripper/test_files.rb
+++ b/test/ripper/test_files.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module TestRipper; end
diff --git a/test/ripper/test_filter.rb b/test/ripper/test_filter.rb
index 005a5d81e28333..0f9d38f7266c13 100644
--- a/test/ripper/test_filter.rb
+++ b/test/ripper/test_filter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'ripper'
   require 'test/unit'
@@ -76,7 +77,7 @@ def test_filter_column
 
   def test_filter_token
     data = {}
-    filter = Filter.new(File.read(filename))
+    filter = Filter.new("begin; puts 1; end")
     filter.parse(data)
     assert_equal("begin", data[:token])
   end
diff --git a/test/ripper/test_ripper.rb b/test/ripper/test_ripper.rb
index 1544e5682f1eb5..e0b65a04d8948a 100644
--- a/test/ripper/test_ripper.rb
+++ b/test/ripper/test_ripper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'ripper'
   require 'test/unit'
diff --git a/test/ripper/test_scanner_events.rb b/test/ripper/test_scanner_events.rb
index 45c16738d0d4cf..ab52392eb1b8eb 100644
--- a/test/ripper/test_scanner_events.rb
+++ b/test/ripper/test_scanner_events.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # test_scanner_events.rb
 #
diff --git a/test/ripper/test_sexp.rb b/test/ripper/test_sexp.rb
index 557ae9b4233ae7..46fb7f292aa9f1 100644
--- a/test/ripper/test_sexp.rb
+++ b/test/ripper/test_sexp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'ripper'
   require 'test/unit'
diff --git a/test/rss/rss-assertions.rb b/test/rss/rss-assertions.rb
index f2e9dc07c9955e..1bafb02f86c75c 100644
--- a/test/rss/rss-assertions.rb
+++ b/test/rss/rss-assertions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'erb'
 
 module RSS
diff --git a/test/rss/rss-testcase.rb b/test/rss/rss-testcase.rb
index 2e39433d4a8b99..30067d43b2d201 100644
--- a/test/rss/rss-testcase.rb
+++ b/test/rss/rss-testcase.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "erb"
 
 require "test/unit"
diff --git a/test/rss/test_1.0.rb b/test/rss/test_1.0.rb
index 758eecf51da08d..33ae29141bdec7 100644
--- a/test/rss/test_1.0.rb
+++ b/test/rss/test_1.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/document"
 
 require_relative "rss-testcase"
diff --git a/test/rss/test_2.0.rb b/test/rss/test_2.0.rb
index 37285cefa3f812..650f8350105259 100644
--- a/test/rss/test_2.0.rb
+++ b/test/rss/test_2.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/document"
 
 require_relative "rss-testcase"
diff --git a/test/rss/test_accessor.rb b/test/rss/test_accessor.rb
index ea15316a5ddb13..7d4424dbbdcaf1 100644
--- a/test/rss/test_accessor.rb
+++ b/test/rss/test_accessor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/1.0"
diff --git a/test/rss/test_atom.rb b/test/rss/test_atom.rb
index 557cb803249ac7..774064eff76c0b 100644
--- a/test/rss/test_atom.rb
+++ b/test/rss/test_atom.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/document"
 
 require_relative "rss-testcase"
diff --git a/test/rss/test_content.rb b/test/rss/test_content.rb
index 13f22a2152680f..fc8269df129205 100644
--- a/test/rss/test_content.rb
+++ b/test/rss/test_content.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "cgi"
 require "rexml/document"
 
diff --git a/test/rss/test_dublincore.rb b/test/rss/test_dublincore.rb
index eb03d84957162c..37ef1771993cbe 100644
--- a/test/rss/test_dublincore.rb
+++ b/test/rss/test_dublincore.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "cgi"
 require "rexml/document"
 
diff --git a/test/rss/test_image.rb b/test/rss/test_image.rb
index d8f0b26103d768..0f1cd8c9e28fc8 100644
--- a/test/rss/test_image.rb
+++ b/test/rss/test_image.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "cgi"
 require "rexml/document"
 
diff --git a/test/rss/test_inherit.rb b/test/rss/test_inherit.rb
index 8b640dc319392f..020f066c5f8d66 100644
--- a/test/rss/test_inherit.rb
+++ b/test/rss/test_inherit.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/1.0"
diff --git a/test/rss/test_itunes.rb b/test/rss/test_itunes.rb
index ec06337f7de43c..7be001062ba84c 100644
--- a/test/rss/test_itunes.rb
+++ b/test/rss/test_itunes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "cgi"
 require "rexml/document"
 
diff --git a/test/rss/test_maker_0.9.rb b/test/rss/test_maker_0.9.rb
index f6e39c60b75a06..64d04bcd10eda2 100644
--- a/test/rss/test_maker_0.9.rb
+++ b/test/rss/test_maker_0.9.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_1.0.rb b/test/rss/test_maker_1.0.rb
index b31abb99085731..c8f9977e435f1d 100644
--- a/test/rss/test_maker_1.0.rb
+++ b/test/rss/test_maker_1.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_2.0.rb b/test/rss/test_maker_2.0.rb
index 48c0f91f485d17..8528611e5319d1 100644
--- a/test/rss/test_maker_2.0.rb
+++ b/test/rss/test_maker_2.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_atom_entry.rb b/test/rss/test_maker_atom_entry.rb
index 9618723e6280ac..8e41c7c50ebe25 100644
--- a/test/rss/test_maker_atom_entry.rb
+++ b/test/rss/test_maker_atom_entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_atom_feed.rb b/test/rss/test_maker_atom_feed.rb
index d86600113d5f27..d4eacd36ad1fb1 100644
--- a/test/rss/test_maker_atom_feed.rb
+++ b/test/rss/test_maker_atom_feed.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_content.rb b/test/rss/test_maker_content.rb
index ba884f16a31406..e3b84c53a41141 100644
--- a/test/rss/test_maker_content.rb
+++ b/test/rss/test_maker_content.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_dc.rb b/test/rss/test_maker_dc.rb
index 977350ca75dc83..f5c8bad2b30c9d 100644
--- a/test/rss/test_maker_dc.rb
+++ b/test/rss/test_maker_dc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_image.rb b/test/rss/test_maker_image.rb
index d01654c91bdd80..cc663c6a5cd801 100644
--- a/test/rss/test_maker_image.rb
+++ b/test/rss/test_maker_image.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_itunes.rb b/test/rss/test_maker_itunes.rb
index 0d47171fdd862a..03092b1c41449e 100644
--- a/test/rss/test_maker_itunes.rb
+++ b/test/rss/test_maker_itunes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_slash.rb b/test/rss/test_maker_slash.rb
index ea95a99b6888ab..5e5761ab0f61db 100644
--- a/test/rss/test_maker_slash.rb
+++ b/test/rss/test_maker_slash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_sy.rb b/test/rss/test_maker_sy.rb
index 7117e3af0c43b6..6f4d6f839075d7 100644
--- a/test/rss/test_maker_sy.rb
+++ b/test/rss/test_maker_sy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_taxo.rb b/test/rss/test_maker_taxo.rb
index 4c4c2e336a11f6..9a19a52dc46e68 100644
--- a/test/rss/test_maker_taxo.rb
+++ b/test/rss/test_maker_taxo.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_trackback.rb b/test/rss/test_maker_trackback.rb
index 411bf319ca0183..b49e5c3f57cb50 100644
--- a/test/rss/test_maker_trackback.rb
+++ b/test/rss/test_maker_trackback.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_maker_xml-stylesheet.rb b/test/rss/test_maker_xml-stylesheet.rb
index 4f7c62aaeb7caf..4563de9902aefb 100644
--- a/test/rss/test_maker_xml-stylesheet.rb
+++ b/test/rss/test_maker_xml-stylesheet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_parser.rb b/test/rss/test_parser.rb
index 8d8d1e19707991..7d64657d579ecb 100644
--- a/test/rss/test_parser.rb
+++ b/test/rss/test_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "tempfile"
 
 require_relative "rss-testcase"
diff --git a/test/rss/test_parser_1.0.rb b/test/rss/test_parser_1.0.rb
index 2efecdaf356651..f7be5153af4e4a 100644
--- a/test/rss/test_parser_1.0.rb
+++ b/test/rss/test_parser_1.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/1.0"
diff --git a/test/rss/test_parser_2.0.rb b/test/rss/test_parser_2.0.rb
index 68c7d1cca0d864..ac7a67b8b16d59 100644
--- a/test/rss/test_parser_2.0.rb
+++ b/test/rss/test_parser_2.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/2.0"
diff --git a/test/rss/test_parser_atom_entry.rb b/test/rss/test_parser_atom_entry.rb
index 352fbbe7f9e981..4f54ba3cadbaa1 100644
--- a/test/rss/test_parser_atom_entry.rb
+++ b/test/rss/test_parser_atom_entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/atom"
diff --git a/test/rss/test_parser_atom_feed.rb b/test/rss/test_parser_atom_feed.rb
index a5731b2f6735a1..626062d23aeca4 100644
--- a/test/rss/test_parser_atom_feed.rb
+++ b/test/rss/test_parser_atom_feed.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/atom"
diff --git a/test/rss/test_setup_maker_0.9.rb b/test/rss/test_setup_maker_0.9.rb
index 2714b9ceced39d..4eae62417a982a 100644
--- a/test/rss/test_setup_maker_0.9.rb
+++ b/test/rss/test_setup_maker_0.9.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_setup_maker_1.0.rb b/test/rss/test_setup_maker_1.0.rb
index 0408ca911ef5c9..a9d60ddb979fdc 100644
--- a/test/rss/test_setup_maker_1.0.rb
+++ b/test/rss/test_setup_maker_1.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_setup_maker_2.0.rb b/test/rss/test_setup_maker_2.0.rb
index fcf1f57836905d..dffffe6da9e71e 100644
--- a/test/rss/test_setup_maker_2.0.rb
+++ b/test/rss/test_setup_maker_2.0.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_setup_maker_atom_entry.rb b/test/rss/test_setup_maker_atom_entry.rb
index ec9df5e70a40f3..f8649ea185674d 100644
--- a/test/rss/test_setup_maker_atom_entry.rb
+++ b/test/rss/test_setup_maker_atom_entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_setup_maker_atom_feed.rb b/test/rss/test_setup_maker_atom_feed.rb
index ad2c6939d2746f..2196f1a46a440e 100644
--- a/test/rss/test_setup_maker_atom_feed.rb
+++ b/test/rss/test_setup_maker_atom_feed.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_setup_maker_itunes.rb b/test/rss/test_setup_maker_itunes.rb
index 246fecf4c0fb4a..35ecfb4829a034 100644
--- a/test/rss/test_setup_maker_itunes.rb
+++ b/test/rss/test_setup_maker_itunes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_setup_maker_slash.rb b/test/rss/test_setup_maker_slash.rb
index cd12db9f918145..d6973bed4e68ba 100644
--- a/test/rss/test_setup_maker_slash.rb
+++ b/test/rss/test_setup_maker_slash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 require "rss/maker"
diff --git a/test/rss/test_slash.rb b/test/rss/test_slash.rb
index 757e7879f2724c..6746e4488ffcf5 100644
--- a/test/rss/test_slash.rb
+++ b/test/rss/test_slash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "cgi"
 require "rexml/document"
 
diff --git a/test/rss/test_syndication.rb b/test/rss/test_syndication.rb
index 17875f19544d4c..ec3895eafc7b2c 100644
--- a/test/rss/test_syndication.rb
+++ b/test/rss/test_syndication.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "cgi"
 require "rexml/document"
 
diff --git a/test/rss/test_taxonomy.rb b/test/rss/test_taxonomy.rb
index 34937e4367b323..89f49a94c34753 100644
--- a/test/rss/test_taxonomy.rb
+++ b/test/rss/test_taxonomy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "cgi"
 
 require_relative "rss-testcase"
diff --git a/test/rss/test_to_s.rb b/test/rss/test_to_s.rb
index d97cf9d4b0381e..b8ef0d8da441c3 100644
--- a/test/rss/test_to_s.rb
+++ b/test/rss/test_to_s.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/document"
 
 require_relative "rss-testcase"
diff --git a/test/rss/test_trackback.rb b/test/rss/test_trackback.rb
index 8560c254f0d014..2910b4b344a386 100644
--- a/test/rss/test_trackback.rb
+++ b/test/rss/test_trackback.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "cgi"
 require "rexml/document"
 
diff --git a/test/rss/test_version.rb b/test/rss/test_version.rb
index d2175ab76a32f4..731e7e5e2042f9 100644
--- a/test/rss/test_version.rb
+++ b/test/rss/test_version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require_relative "rss-testcase"
 
 module RSS
diff --git a/test/rss/test_xml-stylesheet.rb b/test/rss/test_xml-stylesheet.rb
index c67922f4ec5dae..71be1d8feaa3f4 100644
--- a/test/rss/test_xml-stylesheet.rb
+++ b/test/rss/test_xml-stylesheet.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rexml/document"
 
 require_relative "rss-testcase"
diff --git a/test/ruby/allpairs.rb b/test/ruby/allpairs.rb
index 27b6f5988f6d02..e5893e252a504e 100644
--- a/test/ruby/allpairs.rb
+++ b/test/ruby/allpairs.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 module AllPairs
   module_function
 
diff --git a/test/ruby/beginmainend.rb b/test/ruby/beginmainend.rb
index ddd4d254c6f4ca..b6de5d65fd6c68 100644
--- a/test/ruby/beginmainend.rb
+++ b/test/ruby/beginmainend.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 BEGIN {
   puts "b1"
   # local_begin1 = "local_begin1"
diff --git a/test/ruby/enc/test_big5.rb b/test/ruby/enc/test_big5.rb
index e8fe0270a84860..5dcf93e8e3a4d9 100644
--- a/test/ruby/enc/test_big5.rb
+++ b/test/ruby/enc/test_big5.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 
 class TestBig5 < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_cp949.rb b/test/ruby/enc/test_cp949.rb
index e675c7b80cfece..0684162d5bf39b 100644
--- a/test/ruby/enc/test_cp949.rb
+++ b/test/ruby/enc/test_cp949.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 
 class TestCP949 < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_emoji.rb b/test/ruby/enc/test_emoji.rb
index 1f80c5a79ef20b..330ff70cb95cc1 100644
--- a/test/ruby/enc/test_emoji.rb
+++ b/test/ruby/enc/test_emoji.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module Emoji
diff --git a/test/ruby/enc/test_euc_jp.rb b/test/ruby/enc/test_euc_jp.rb
index 510ee4611e33ed..4aec69e4dbc63a 100644
--- a/test/ruby/enc/test_euc_jp.rb
+++ b/test/ruby/enc/test_euc_jp.rb
@@ -1,4 +1,5 @@
 # vim: set fileencoding=euc-jp
+# frozen_string_literal: false
 
 require "test/unit"
 
diff --git a/test/ruby/enc/test_euc_kr.rb b/test/ruby/enc/test_euc_kr.rb
index 5413fa6062e579..c9de2cc4e1378b 100644
--- a/test/ruby/enc/test_euc_kr.rb
+++ b/test/ruby/enc/test_euc_kr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 
 class TestEucKr < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_euc_tw.rb b/test/ruby/enc/test_euc_tw.rb
index f36d86b088aee2..649b1b81c6a963 100644
--- a/test/ruby/enc/test_euc_tw.rb
+++ b/test/ruby/enc/test_euc_tw.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 
 class TestEucTw < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_gb18030.rb b/test/ruby/enc/test_gb18030.rb
index f379504d485ab6..76ac7859517685 100644
--- a/test/ruby/enc/test_gb18030.rb
+++ b/test/ruby/enc/test_gb18030.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 
 class TestGB18030 < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_gbk.rb b/test/ruby/enc/test_gbk.rb
index d6dc5d6d1b51a4..2e541b58217411 100644
--- a/test/ruby/enc/test_gbk.rb
+++ b/test/ruby/enc/test_gbk.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 
 class TestGBK < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_iso_8859.rb b/test/ruby/enc/test_iso_8859.rb
index 64cc7cd76da62c..f6b3b3f28b441e 100644
--- a/test/ruby/enc/test_iso_8859.rb
+++ b/test/ruby/enc/test_iso_8859.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestISO8859 < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_koi8.rb b/test/ruby/enc/test_koi8.rb
index ce2d8925eab77b..4a4d233e8d686d 100644
--- a/test/ruby/enc/test_koi8.rb
+++ b/test/ruby/enc/test_koi8.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 
 class TestKOI8 < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_shift_jis.rb b/test/ruby/enc/test_shift_jis.rb
index 1bd47fa8599550..059992d1670077 100644
--- a/test/ruby/enc/test_shift_jis.rb
+++ b/test/ruby/enc/test_shift_jis.rb
@@ -1,4 +1,5 @@
 # vim: set fileencoding=shift_jis
+# frozen_string_literal: false
 
 require "test/unit"
 
diff --git a/test/ruby/enc/test_utf16.rb b/test/ruby/enc/test_utf16.rb
index 63929c6f4b0a47..99b48c298259e5 100644
--- a/test/ruby/enc/test_utf16.rb
+++ b/test/ruby/enc/test_utf16.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestUTF16 < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_utf32.rb b/test/ruby/enc/test_utf32.rb
index 29a22405987e1c..23e8aeb315fd8b 100644
--- a/test/ruby/enc/test_utf32.rb
+++ b/test/ruby/enc/test_utf32.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestUTF32 < Test::Unit::TestCase
diff --git a/test/ruby/enc/test_windows_1251.rb b/test/ruby/enc/test_windows_1251.rb
index 6fbf3159a19f40..002dbaa3cc22d2 100644
--- a/test/ruby/enc/test_windows_1251.rb
+++ b/test/ruby/enc/test_windows_1251.rb
@@ -1,4 +1,5 @@
 # encoding:windows-1251
+# frozen_string_literal: false
 
 require "test/unit"
 
diff --git a/test/ruby/enc/test_windows_1252.rb b/test/ruby/enc/test_windows_1252.rb
index 72ee3d201a1de3..f264cba759a465 100644
--- a/test/ruby/enc/test_windows_1252.rb
+++ b/test/ruby/enc/test_windows_1252.rb
@@ -1,4 +1,5 @@
 # encoding:windows-1252
+# frozen_string_literal: false
 
 require "test/unit"
 
diff --git a/test/ruby/lbtest.rb b/test/ruby/lbtest.rb
index ae047fb187d2c1..591656af77e6c8 100644
--- a/test/ruby/lbtest.rb
+++ b/test/ruby/lbtest.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'thread'
 
 class LocalBarrier
diff --git a/test/ruby/marshaltestlib.rb b/test/ruby/marshaltestlib.rb
index 665d365a9a29ce..358d3c5133e3f8 100644
--- a/test/ruby/marshaltestlib.rb
+++ b/test/ruby/marshaltestlib.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 module MarshalTestLib
   # include this module to a Test::Unit::TestCase and define encode(o) and
   # decode(s) methods.  e.g.
diff --git a/test/ruby/sentence.rb b/test/ruby/sentence.rb
index 50f42d6885e329..28fb5d1cf8eb5b 100644
--- a/test/ruby/sentence.rb
+++ b/test/ruby/sentence.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # == sentence library
 #
 # = Features
diff --git a/test/ruby/test_alias.rb b/test/ruby/test_alias.rb
index 802c1963553636..d5bbce3ddaa2ea 100644
--- a/test/ruby/test_alias.rb
+++ b/test/ruby/test_alias.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestAlias < Test::Unit::TestCase
diff --git a/test/ruby/test_argf.rb b/test/ruby/test_argf.rb
index e40b038967085f..d4be87e954219e 100644
--- a/test/ruby/test_argf.rb
+++ b/test/ruby/test_argf.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 require 'tmpdir'
diff --git a/test/ruby/test_arity.rb b/test/ruby/test_arity.rb
index 4a24bdc66012d7..b98248f6036c04 100644
--- a/test/ruby/test_arity.rb
+++ b/test/ruby/test_arity.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestArity < Test::Unit::TestCase
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index d2af339a1186fa..b1fc473f8617f6 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestArray < Test::Unit::TestCase
diff --git a/test/ruby/test_assignment.rb b/test/ruby/test_assignment.rb
index 315f7baef6b690..d0f2fadeaab695 100644
--- a/test/ruby/test_assignment.rb
+++ b/test/ruby/test_assignment.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestAssignment < Test::Unit::TestCase
diff --git a/test/ruby/test_autoload.rb b/test/ruby/test_autoload.rb
index a672e0be5a2940..b793fd2a7fb2f9 100644
--- a/test/ruby/test_autoload.rb
+++ b/test/ruby/test_autoload.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 require 'thread'
diff --git a/test/ruby/test_backtrace.rb b/test/ruby/test_backtrace.rb
index 3076f37017b18b..ff95a89e674fa5 100644
--- a/test/ruby/test_backtrace.rb
+++ b/test/ruby/test_backtrace.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'thread'
 require 'tempfile'
diff --git a/test/ruby/test_basicinstructions.rb b/test/ruby/test_basicinstructions.rb
index 4a1dc9ce128641..b56b6d116db912 100644
--- a/test/ruby/test_basicinstructions.rb
+++ b/test/ruby/test_basicinstructions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 ConstTest = 3
diff --git a/test/ruby/test_beginendblock.rb b/test/ruby/test_beginendblock.rb
index 9445fa6f9570c2..0c88e9eb230d5a 100644
--- a/test/ruby/test_beginendblock.rb
+++ b/test/ruby/test_beginendblock.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestBeginEndBlock < Test::Unit::TestCase
diff --git a/test/ruby/test_bignum.rb b/test/ruby/test_bignum.rb
index d057e39dbd2235..93afbe44af8a26 100644
--- a/test/ruby/test_bignum.rb
+++ b/test/ruby/test_bignum.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestBignum < Test::Unit::TestCase
diff --git a/test/ruby/test_call.rb b/test/ruby/test_call.rb
index 04966f40f78df7..7ef8d06936cbd6 100644
--- a/test/ruby/test_call.rb
+++ b/test/ruby/test_call.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestCall < Test::Unit::TestCase
diff --git a/test/ruby/test_case.rb b/test/ruby/test_case.rb
index b9f8ab264dd869..861fd8ea064b81 100644
--- a/test/ruby/test_case.rb
+++ b/test/ruby/test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestCase < Test::Unit::TestCase
diff --git a/test/ruby/test_class.rb b/test/ruby/test_class.rb
index 1d9ee55d7ac09e..e60db37c15f979 100644
--- a/test/ruby/test_class.rb
+++ b/test/ruby/test_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestClass < Test::Unit::TestCase
diff --git a/test/ruby/test_clone.rb b/test/ruby/test_clone.rb
index c5e2469d10a140..93ef438461b4c9 100644
--- a/test/ruby/test_clone.rb
+++ b/test/ruby/test_clone.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestClone < Test::Unit::TestCase
diff --git a/test/ruby/test_comparable.rb b/test/ruby/test_comparable.rb
index dab6be5b278ec7..7624ef2bd349d4 100644
--- a/test/ruby/test_comparable.rb
+++ b/test/ruby/test_comparable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestComparable < Test::Unit::TestCase
diff --git a/test/ruby/test_complex.rb b/test/ruby/test_complex.rb
index de3bb05d6cb5df..e51dec01cf4a5a 100644
--- a/test/ruby/test_complex.rb
+++ b/test/ruby/test_complex.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class ComplexSub < Complex; end
diff --git a/test/ruby/test_complex2.rb b/test/ruby/test_complex2.rb
index 3ee7810dc6026e..594fc3f45a61eb 100644
--- a/test/ruby/test_complex2.rb
+++ b/test/ruby/test_complex2.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class Complex_Test2 < Test::Unit::TestCase
diff --git a/test/ruby/test_complexrational.rb b/test/ruby/test_complexrational.rb
index cef4074afa91d7..7c80e1a295db3a 100644
--- a/test/ruby/test_complexrational.rb
+++ b/test/ruby/test_complexrational.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class ComplexRational_Test < Test::Unit::TestCase
diff --git a/test/ruby/test_condition.rb b/test/ruby/test_condition.rb
index ba2e0688f3d833..ab0ffc4b6a2559 100644
--- a/test/ruby/test_condition.rb
+++ b/test/ruby/test_condition.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestCondition < Test::Unit::TestCase
diff --git a/test/ruby/test_const.rb b/test/ruby/test_const.rb
index 8d504649889297..0b2c4497c62e16 100644
--- a/test/ruby/test_const.rb
+++ b/test/ruby/test_const.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestConst < Test::Unit::TestCase
diff --git a/test/ruby/test_continuation.rb b/test/ruby/test_continuation.rb
index 8d57b8bc25b53c..efc549b67a1984 100644
--- a/test/ruby/test_continuation.rb
+++ b/test/ruby/test_continuation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 EnvUtil.suppress_warning {require 'continuation'}
 require 'fiber'
diff --git a/test/ruby/test_defined.rb b/test/ruby/test_defined.rb
index 95a46ed984793b..de7ba9cc140477 100644
--- a/test/ruby/test_defined.rb
+++ b/test/ruby/test_defined.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestDefined < Test::Unit::TestCase
diff --git a/test/ruby/test_dir.rb b/test/ruby/test_dir.rb
index 510cbf3104f4ea..0cc5a6aa9b2a57 100644
--- a/test/ruby/test_dir.rb
+++ b/test/ruby/test_dir.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 require 'tmpdir'
diff --git a/test/ruby/test_dir_m17n.rb b/test/ruby/test_dir_m17n.rb
index bb60b0af766283..febfbc0511f432 100644
--- a/test/ruby/test_dir_m17n.rb
+++ b/test/ruby/test_dir_m17n.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 
diff --git a/test/ruby/test_econv.rb b/test/ruby/test_econv.rb
index 5690ec75f2faaf..8172bf99ef60c6 100644
--- a/test/ruby/test_econv.rb
+++ b/test/ruby/test_econv.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestEncodingConverter < Test::Unit::TestCase
diff --git a/test/ruby/test_encoding.rb b/test/ruby/test_encoding.rb
index abe4317ff6d373..06559651c551a4 100644
--- a/test/ruby/test_encoding.rb
+++ b/test/ruby/test_encoding.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestEncoding < Test::Unit::TestCase
diff --git a/test/ruby/test_enum.rb b/test/ruby/test_enum.rb
index 4a6aa5e36e183f..ab3564491a9136 100644
--- a/test/ruby/test_enum.rb
+++ b/test/ruby/test_enum.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 EnvUtil.suppress_warning {require 'continuation'}
 require 'stringio'
diff --git a/test/ruby/test_enumerator.rb b/test/ruby/test_enumerator.rb
index e81d2e4e725b3c..aa36187ba2bb18 100644
--- a/test/ruby/test_enumerator.rb
+++ b/test/ruby/test_enumerator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestEnumerator < Test::Unit::TestCase
diff --git a/test/ruby/test_env.rb b/test/ruby/test_env.rb
index f7c6e61de5afb2..c1617cce7e2a95 100644
--- a/test/ruby/test_env.rb
+++ b/test/ruby/test_env.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestEnv < Test::Unit::TestCase
diff --git a/test/ruby/test_eval.rb b/test/ruby/test_eval.rb
index 02dbb9b379dfa5..6982429b5104eb 100644
--- a/test/ruby/test_eval.rb
+++ b/test/ruby/test_eval.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestEval < Test::Unit::TestCase
diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index 707a99f8059adb..1148277a1b556c 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 
diff --git a/test/ruby/test_extlibs.rb b/test/ruby/test_extlibs.rb
index 995baa0d32a95e..4d14ed45a85111 100644
--- a/test/ruby/test_extlibs.rb
+++ b/test/ruby/test_extlibs.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "envutil"
 require "shellwords"
 
diff --git a/test/ruby/test_fiber.rb b/test/ruby/test_fiber.rb
index 4684a65a03c466..fed5d3d2c647f7 100644
--- a/test/ruby/test_fiber.rb
+++ b/test/ruby/test_fiber.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'fiber'
 EnvUtil.suppress_warning {require 'continuation'}
diff --git a/test/ruby/test_file.rb b/test/ruby/test_file.rb
index 3599d168d1a0bf..88b934d8ef0d84 100644
--- a/test/ruby/test_file.rb
+++ b/test/ruby/test_file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 require "thread"
diff --git a/test/ruby/test_file_exhaustive.rb b/test/ruby/test_file_exhaustive.rb
index e4b92152e53417..8070d57bd0aba1 100644
--- a/test/ruby/test_file_exhaustive.rb
+++ b/test/ruby/test_file_exhaustive.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "fileutils"
 require "tmpdir"
diff --git a/test/ruby/test_fixnum.rb b/test/ruby/test_fixnum.rb
index e10371d3e3490b..b5b642504f7481 100644
--- a/test/ruby/test_fixnum.rb
+++ b/test/ruby/test_fixnum.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestFixnum < Test::Unit::TestCase
diff --git a/test/ruby/test_flip.rb b/test/ruby/test_flip.rb
index 84f7bf05621d12..594c8101b9f941 100644
--- a/test/ruby/test_flip.rb
+++ b/test/ruby/test_flip.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestFlip < Test::Unit::TestCase
diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb
index f1e01fc249b2a2..3afd26d0b4d2ea 100644
--- a/test/ruby/test_float.rb
+++ b/test/ruby/test_float.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestFloat < Test::Unit::TestCase
diff --git a/test/ruby/test_fnmatch.rb b/test/ruby/test_fnmatch.rb
index a0eab545e44c80..ca01a286989a20 100644
--- a/test/ruby/test_fnmatch.rb
+++ b/test/ruby/test_fnmatch.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestFnmatch < Test::Unit::TestCase
diff --git a/test/ruby/test_gc.rb b/test/ruby/test_gc.rb
index f7ee182e83720c..0e3ae4bc420358 100644
--- a/test/ruby/test_gc.rb
+++ b/test/ruby/test_gc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestGc < Test::Unit::TestCase
diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index 01990618fb97e1..6ee029722a8000 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 EnvUtil.suppress_warning {require 'continuation'}
 
diff --git a/test/ruby/test_ifunless.rb b/test/ruby/test_ifunless.rb
index e144ff8efd3134..d533e155bc136c 100644
--- a/test/ruby/test_ifunless.rb
+++ b/test/ruby/test_ifunless.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestIfunless < Test::Unit::TestCase
diff --git a/test/ruby/test_integer.rb b/test/ruby/test_integer.rb
index 3dbf365a7c75dd..64b8e1e2c1f505 100644
--- a/test/ruby/test_integer.rb
+++ b/test/ruby/test_integer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestInteger < Test::Unit::TestCase
diff --git a/test/ruby/test_integer_comb.rb b/test/ruby/test_integer_comb.rb
index 90185183347c76..c96b34a477c513 100644
--- a/test/ruby/test_integer_comb.rb
+++ b/test/ruby/test_integer_comb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestIntegerComb < Test::Unit::TestCase
diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index bd92634785bd6e..bb6503a2dbfec8 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 require "fcntl"
diff --git a/test/ruby/test_io_m17n.rb b/test/ruby/test_io_m17n.rb
index ed8ac99946bac1..233b93d0b3ed4f 100644
--- a/test/ruby/test_io_m17n.rb
+++ b/test/ruby/test_io_m17n.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 require 'tempfile'
diff --git a/test/ruby/test_iterator.rb b/test/ruby/test_iterator.rb
index 34652db2bb5b90..fb81820ebf304a 100644
--- a/test/ruby/test_iterator.rb
+++ b/test/ruby/test_iterator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class Array
diff --git a/test/ruby/test_keyword.rb b/test/ruby/test_keyword.rb
index 9c76e15c38a4f7..f6923248ff33fc 100644
--- a/test/ruby/test_keyword.rb
+++ b/test/ruby/test_keyword.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestKeywordArguments < Test::Unit::TestCase
diff --git a/test/ruby/test_lambda.rb b/test/ruby/test_lambda.rb
index b2b4c9c90733e4..f61e8a9f6277f8 100644
--- a/test/ruby/test_lambda.rb
+++ b/test/ruby/test_lambda.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestLambdaParameters < Test::Unit::TestCase
diff --git a/test/ruby/test_lazy_enumerator.rb b/test/ruby/test_lazy_enumerator.rb
index a0c506871009bc..29c6b3e8555f65 100644
--- a/test/ruby/test_lazy_enumerator.rb
+++ b/test/ruby/test_lazy_enumerator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestLazyEnumerator < Test::Unit::TestCase
diff --git a/test/ruby/test_literal.rb b/test/ruby/test_literal.rb
index e523f11cd7ed13..522ca53ea441df 100644
--- a/test/ruby/test_literal.rb
+++ b/test/ruby/test_literal.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestRubyLiteral < Test::Unit::TestCase
diff --git a/test/ruby/test_m17n.rb b/test/ruby/test_m17n.rb
index a9cb86a5c840dc..74b847a8259993 100644
--- a/test/ruby/test_m17n.rb
+++ b/test/ruby/test_m17n.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestM17N < Test::Unit::TestCase
diff --git a/test/ruby/test_m17n_comb.rb b/test/ruby/test_m17n_comb.rb
index cf00e521572d9e..054287e2b5fba3 100644
--- a/test/ruby/test_m17n_comb.rb
+++ b/test/ruby/test_m17n_comb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'etc'
 require_relative 'allpairs'
diff --git a/test/ruby/test_marshal.rb b/test/ruby/test_marshal.rb
index 145244ec10a244..482637fa12781e 100644
--- a/test/ruby/test_marshal.rb
+++ b/test/ruby/test_marshal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 require_relative 'marshaltestlib'
diff --git a/test/ruby/test_math.rb b/test/ruby/test_math.rb
index 674bb541e55adf..f2805a2d748345 100644
--- a/test/ruby/test_math.rb
+++ b/test/ruby/test_math.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestMath < Test::Unit::TestCase
diff --git a/test/ruby/test_metaclass.rb b/test/ruby/test_metaclass.rb
index 6386a02dfac5de..8c1990a78cfb2c 100644
--- a/test/ruby/test_metaclass.rb
+++ b/test/ruby/test_metaclass.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestMetaclass < Test::Unit::TestCase
diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index 48178c4d7ad4c5..cc2c9873c5e8de 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestMethod < Test::Unit::TestCase
diff --git a/test/ruby/test_mixed_unicode_escapes.rb b/test/ruby/test_mixed_unicode_escapes.rb
index ac712db0f8c277..09240d8ab27465 100644
--- a/test/ruby/test_mixed_unicode_escapes.rb
+++ b/test/ruby/test_mixed_unicode_escapes.rb
@@ -1,4 +1,5 @@
 # -*- coding: cp932 -*-
+# frozen_string_literal: false
 # This test is in a different file than TestUnicodeEscapes
 # So that we can have a different coding comment above
 
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index b86efd7005609d..53569831352654 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'pp'
 
diff --git a/test/ruby/test_not.rb b/test/ruby/test_not.rb
index 486075bf837393..721f868a5a1e34 100644
--- a/test/ruby/test_not.rb
+++ b/test/ruby/test_not.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestIfunless < Test::Unit::TestCase
diff --git a/test/ruby/test_notimp.rb b/test/ruby/test_notimp.rb
index 9721723b29823f..a9ab8f328fd84a 100644
--- a/test/ruby/test_notimp.rb
+++ b/test/ruby/test_notimp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 require 'tmpdir'
diff --git a/test/ruby/test_numeric.rb b/test/ruby/test_numeric.rb
index f539ccf731f4e5..ad5e2831524104 100644
--- a/test/ruby/test_numeric.rb
+++ b/test/ruby/test_numeric.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestNumeric < Test::Unit::TestCase
diff --git a/test/ruby/test_object.rb b/test/ruby/test_object.rb
index 29ce7ac76dd3d0..0ab134170d343e 100644
--- a/test/ruby/test_object.rb
+++ b/test/ruby/test_object.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestObject < Test::Unit::TestCase
diff --git a/test/ruby/test_objectspace.rb b/test/ruby/test_objectspace.rb
index cb17d034170a83..b701e0fc913746 100644
--- a/test/ruby/test_objectspace.rb
+++ b/test/ruby/test_objectspace.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestObjectSpace < Test::Unit::TestCase
diff --git a/test/ruby/test_optimization.rb b/test/ruby/test_optimization.rb
index 3573d1267f2992..2115fc849dc893 100644
--- a/test/ruby/test_optimization.rb
+++ b/test/ruby/test_optimization.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'objspace'
 
diff --git a/test/ruby/test_pack.rb b/test/ruby/test_pack.rb
index d696dd70a13a60..2d7c0ae8e6c507 100644
--- a/test/ruby/test_pack.rb
+++ b/test/ruby/test_pack.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestPack < Test::Unit::TestCase
diff --git a/test/ruby/test_parse.rb b/test/ruby/test_parse.rb
index 673b0e7b74ab92..6560618b118b4b 100644
--- a/test/ruby/test_parse.rb
+++ b/test/ruby/test_parse.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 require 'stringio'
 
diff --git a/test/ruby/test_path.rb b/test/ruby/test_path.rb
index b604a763f193ff..6af4fb6ac0167d 100644
--- a/test/ruby/test_path.rb
+++ b/test/ruby/test_path.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestPath < Test::Unit::TestCase
diff --git a/test/ruby/test_pipe.rb b/test/ruby/test_pipe.rb
index bcea91bebb6239..efca8f28c1f51b 100644
--- a/test/ruby/test_pipe.rb
+++ b/test/ruby/test_pipe.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require_relative 'ut_eof'
 
diff --git a/test/ruby/test_primitive.rb b/test/ruby/test_primitive.rb
index 9d451e2ae08d0d..d1503a562b9d14 100644
--- a/test/ruby/test_primitive.rb
+++ b/test/ruby/test_primitive.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestRubyPrimitive < Test::Unit::TestCase
diff --git a/test/ruby/test_proc.rb b/test/ruby/test_proc.rb
index e13bf59598f93a..fa247f2fc07a1f 100644
--- a/test/ruby/test_proc.rb
+++ b/test/ruby/test_proc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestProc < Test::Unit::TestCase
diff --git a/test/ruby/test_process.rb b/test/ruby/test_process.rb
index 2e120ef9bb7855..ca35d151a9e004 100644
--- a/test/ruby/test_process.rb
+++ b/test/ruby/test_process.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 require 'timeout'
diff --git a/test/ruby/test_rand.rb b/test/ruby/test_rand.rb
index 4da1559e40345d..d4258a7f1c62d5 100644
--- a/test/ruby/test_rand.rb
+++ b/test/ruby/test_rand.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestRand < Test::Unit::TestCase
diff --git a/test/ruby/test_range.rb b/test/ruby/test_range.rb
index a91f80b07668ba..046f69e9de8af7 100644
--- a/test/ruby/test_range.rb
+++ b/test/ruby/test_range.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'delegate'
 require 'timeout'
diff --git a/test/ruby/test_rational.rb b/test/ruby/test_rational.rb
index f922d8953375d9..ea51ca29f06b5e 100644
--- a/test/ruby/test_rational.rb
+++ b/test/ruby/test_rational.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class RationalSub < Rational; end
diff --git a/test/ruby/test_rational2.rb b/test/ruby/test_rational2.rb
index 3b6a985bc6229f..4e96bf621cf8b0 100644
--- a/test/ruby/test_rational2.rb
+++ b/test/ruby/test_rational2.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class Rational_Test2 < Test::Unit::TestCase
diff --git a/test/ruby/test_readpartial.rb b/test/ruby/test_readpartial.rb
index bc84da7d128cc6..bc22556cd4e9e3 100644
--- a/test/ruby/test_readpartial.rb
+++ b/test/ruby/test_readpartial.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 require 'fcntl'
diff --git a/test/ruby/test_refinement.rb b/test/ruby/test_refinement.rb
index 52b7ac708624f4..99987da9889196 100644
--- a/test/ruby/test_refinement.rb
+++ b/test/ruby/test_refinement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestRefinement < Test::Unit::TestCase
diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index 8e01c0559731fb..ef75d4d4135936 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestRegexp < Test::Unit::TestCase
diff --git a/test/ruby/test_require.rb b/test/ruby/test_require.rb
index 9123d5bc8f0350..a7db8b93e0ffe4 100644
--- a/test/ruby/test_require.rb
+++ b/test/ruby/test_require.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 require 'tempfile'
diff --git a/test/ruby/test_rubyvm.rb b/test/ruby/test_rubyvm.rb
index 580f3be2e192cb..c2d334d04c62e4 100644
--- a/test/ruby/test_rubyvm.rb
+++ b/test/ruby/test_rubyvm.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestRubyVM < Test::Unit::TestCase
diff --git a/test/ruby/test_settracefunc.rb b/test/ruby/test_settracefunc.rb
index e5048adba18d64..fc1391e60fc805 100644
--- a/test/ruby/test_settracefunc.rb
+++ b/test/ruby/test_settracefunc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestSetTraceFunc < Test::Unit::TestCase
diff --git a/test/ruby/test_signal.rb b/test/ruby/test_signal.rb
index 781045d30a9576..13d52013b0beab 100644
--- a/test/ruby/test_signal.rb
+++ b/test/ruby/test_signal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 require 'tempfile'
diff --git a/test/ruby/test_sleep.rb b/test/ruby/test_sleep.rb
index 29490a7a189bc9..61002b8b1872d4 100644
--- a/test/ruby/test_sleep.rb
+++ b/test/ruby/test_sleep.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'etc'
 
diff --git a/test/ruby/test_sprintf.rb b/test/ruby/test_sprintf.rb
index f400e2be6e87c2..1d3badddf9a71c 100644
--- a/test/ruby/test_sprintf.rb
+++ b/test/ruby/test_sprintf.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestSprintf < Test::Unit::TestCase
diff --git a/test/ruby/test_sprintf_comb.rb b/test/ruby/test_sprintf_comb.rb
index c58ddf4f154ed6..41131130309fdd 100644
--- a/test/ruby/test_sprintf_comb.rb
+++ b/test/ruby/test_sprintf_comb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require_relative 'allpairs'
 
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index eed7c69a024e4e..47bd0d56af6459 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestString < Test::Unit::TestCase
diff --git a/test/ruby/test_stringchar.rb b/test/ruby/test_stringchar.rb
index 7f7342c9abdfe8..e13beef69c1883 100644
--- a/test/ruby/test_stringchar.rb
+++ b/test/ruby/test_stringchar.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestStringchar < Test::Unit::TestCase
diff --git a/test/ruby/test_struct.rb b/test/ruby/test_struct.rb
index 19a66fb9b17da7..38632a1981e32f 100644
--- a/test/ruby/test_struct.rb
+++ b/test/ruby/test_struct.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 
diff --git a/test/ruby/test_super.rb b/test/ruby/test_super.rb
index 4f439a6e727004..06e3e6e3b50b34 100644
--- a/test/ruby/test_super.rb
+++ b/test/ruby/test_super.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestSuper < Test::Unit::TestCase
diff --git a/test/ruby/test_symbol.rb b/test/ruby/test_symbol.rb
index a7ffe7b8b97007..0e8417c5ed7fca 100644
--- a/test/ruby/test_symbol.rb
+++ b/test/ruby/test_symbol.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestSymbol < Test::Unit::TestCase
diff --git a/test/ruby/test_syntax.rb b/test/ruby/test_syntax.rb
index dfe58592475761..77cb3ea54e37cc 100644
--- a/test/ruby/test_syntax.rb
+++ b/test/ruby/test_syntax.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestSyntax < Test::Unit::TestCase
diff --git a/test/ruby/test_system.rb b/test/ruby/test_system.rb
index b328cbcc1dcd77..60037ab0444d75 100644
--- a/test/ruby/test_system.rb
+++ b/test/ruby/test_system.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 
diff --git a/test/ruby/test_thread.rb b/test/ruby/test_thread.rb
index e0c61c66f50790..dc929ce4fd1e13 100644
--- a/test/ruby/test_thread.rb
+++ b/test/ruby/test_thread.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# frozen_string_literal: false
 require 'test/unit'
 require 'thread'
 
diff --git a/test/ruby/test_threadgroup.rb b/test/ruby/test_threadgroup.rb
index e158f5ada4a0ff..80b0c153389d9a 100644
--- a/test/ruby/test_threadgroup.rb
+++ b/test/ruby/test_threadgroup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'thread'
 
diff --git a/test/ruby/test_time.rb b/test/ruby/test_time.rb
index 97c6288f4dc917..232d3472c48e1c 100644
--- a/test/ruby/test_time.rb
+++ b/test/ruby/test_time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'delegate'
 require 'timeout'
diff --git a/test/ruby/test_time_tz.rb b/test/ruby/test_time_tz.rb
index a73bd86f0b29da..f5d46905a0fecd 100644
--- a/test/ruby/test_time_tz.rb
+++ b/test/ruby/test_time_tz.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestTimeTZ < Test::Unit::TestCase
diff --git a/test/ruby/test_trace.rb b/test/ruby/test_trace.rb
index 775c458fb1238a..77be94e9beff04 100644
--- a/test/ruby/test_trace.rb
+++ b/test/ruby/test_trace.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestTrace < Test::Unit::TestCase
diff --git a/test/ruby/test_transcode.rb b/test/ruby/test_transcode.rb
index fc74bd02f01d07..33e74671022883 100644
--- a/test/ruby/test_transcode.rb
+++ b/test/ruby/test_transcode.rb
@@ -1,4 +1,5 @@
 # encoding: ASCII-8BIT   # make sure this runs in binary mode
+# frozen_string_literal: false
 # some of the comments are in UTF-8
 
 require 'test/unit'
diff --git a/test/ruby/test_undef.rb b/test/ruby/test_undef.rb
index e1c98076c0fe90..6d513a238fa0ba 100644
--- a/test/ruby/test_undef.rb
+++ b/test/ruby/test_undef.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestUndef < Test::Unit::TestCase
diff --git a/test/ruby/test_unicode_escape.rb b/test/ruby/test_unicode_escape.rb
index 9d0d787e98b195..e0ca430a4a1ad5 100644
--- a/test/ruby/test_unicode_escape.rb
+++ b/test/ruby/test_unicode_escape.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 
 require 'test/unit'
 
diff --git a/test/ruby/test_variable.rb b/test/ruby/test_variable.rb
index 06a8e2f72b41c4..667f9ee24ffa20 100644
--- a/test/ruby/test_variable.rb
+++ b/test/ruby/test_variable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestVariable < Test::Unit::TestCase
diff --git a/test/ruby/test_weakmap.rb b/test/ruby/test_weakmap.rb
index 1279944a37317f..15463bb0304887 100644
--- a/test/ruby/test_weakmap.rb
+++ b/test/ruby/test_weakmap.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestWeakMap < Test::Unit::TestCase
diff --git a/test/ruby/test_whileuntil.rb b/test/ruby/test_whileuntil.rb
index 3d8dbee9948718..394383a7998ea1 100644
--- a/test/ruby/test_whileuntil.rb
+++ b/test/ruby/test_whileuntil.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 
diff --git a/test/ruby/test_yield.rb b/test/ruby/test_yield.rb
index 5c98bb885071ee..0690d3cdf457c9 100644
--- a/test/ruby/test_yield.rb
+++ b/test/ruby/test_yield.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'stringio'
 
diff --git a/test/ruby/ut_eof.rb b/test/ruby/ut_eof.rb
index 83325f2efcdc77..fcd7a63988954c 100644
--- a/test/ruby/ut_eof.rb
+++ b/test/ruby/ut_eof.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 module TestEOF
diff --git a/test/rubygems/bad_rake.rb b/test/rubygems/bad_rake.rb
index 379a4c986e3265..dc603fdec1e867 100644
--- a/test/rubygems/bad_rake.rb
+++ b/test/rubygems/bad_rake.rb
@@ -1 +1,2 @@
+# frozen_string_literal: false
 exit 1
diff --git a/test/rubygems/bogussources.rb b/test/rubygems/bogussources.rb
index 008e3a1de59eae..f51ff60c37f819 100644
--- a/test/rubygems/bogussources.rb
+++ b/test/rubygems/bogussources.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/test/rubygems/fake_certlib/openssl.rb b/test/rubygems/fake_certlib/openssl.rb
index 9de90c0a101f09..2b026df0d8cd0d 100644
--- a/test/rubygems/fake_certlib/openssl.rb
+++ b/test/rubygems/fake_certlib/openssl.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/test/rubygems/fix_openssl_warnings.rb b/test/rubygems/fix_openssl_warnings.rb
index 66d6cdf3eb3c6b..e34551c8a96146 100644
--- a/test/rubygems/fix_openssl_warnings.rb
+++ b/test/rubygems/fix_openssl_warnings.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 ##
 # HACK: this drives me BONKERS
 
diff --git a/test/rubygems/foo/discover.rb b/test/rubygems/foo/discover.rb
index e69de29bb2d1d6..1effd1c8b0fd9f 100644
--- a/test/rubygems/foo/discover.rb
+++ b/test/rubygems/foo/discover.rb
@@ -0,0 +1 @@
+# frozen_string_literal: false
diff --git a/test/rubygems/good_rake.rb b/test/rubygems/good_rake.rb
index ca916d098dabfe..2d5c76c13ab699 100644
--- a/test/rubygems/good_rake.rb
+++ b/test/rubygems/good_rake.rb
@@ -1 +1,2 @@
+# frozen_string_literal: false
 exit 0
diff --git a/test/rubygems/plugin/exception/rubygems_plugin.rb b/test/rubygems/plugin/exception/rubygems_plugin.rb
index 16c417e84d888b..1ab8c553e21cbb 100644
--- a/test/rubygems/plugin/exception/rubygems_plugin.rb
+++ b/test/rubygems/plugin/exception/rubygems_plugin.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: false
 TestGem::TEST_PLUGIN_EXCEPTION = :loaded
 raise Exception.new('boom')
diff --git a/test/rubygems/plugin/load/rubygems_plugin.rb b/test/rubygems/plugin/load/rubygems_plugin.rb
index c7c72777aaf3db..7336fd2b555235 100644
--- a/test/rubygems/plugin/load/rubygems_plugin.rb
+++ b/test/rubygems/plugin/load/rubygems_plugin.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class TestGem
   TEST_PLUGIN_LOAD = :loaded
 end
diff --git a/test/rubygems/plugin/standarderror/rubygems_plugin.rb b/test/rubygems/plugin/standarderror/rubygems_plugin.rb
index 4b577a65183e2a..a0850bf98e583a 100644
--- a/test/rubygems/plugin/standarderror/rubygems_plugin.rb
+++ b/test/rubygems/plugin/standarderror/rubygems_plugin.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: false
 TestGem::TEST_PLUGIN_STANDARDERROR = :loaded
 raise StandardError.new('boom')
diff --git a/test/rubygems/rubygems/commands/crash_command.rb b/test/rubygems/rubygems/commands/crash_command.rb
index 624be9fd3280ff..07692b4609801e 100644
--- a/test/rubygems/rubygems/commands/crash_command.rb
+++ b/test/rubygems/rubygems/commands/crash_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 class Gem::Commands::CrashCommand < Gem::Command
 
   raise "crash"
diff --git a/test/rubygems/rubygems_plugin.rb b/test/rubygems/rubygems_plugin.rb
index 6c08f97c6d4ddd..80f78443b53bec 100644
--- a/test/rubygems/rubygems_plugin.rb
+++ b/test/rubygems/rubygems_plugin.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/command_manager'
 
 ##
diff --git a/test/rubygems/sff/discover.rb b/test/rubygems/sff/discover.rb
index e69de29bb2d1d6..1effd1c8b0fd9f 100644
--- a/test/rubygems/sff/discover.rb
+++ b/test/rubygems/sff/discover.rb
@@ -0,0 +1 @@
+# frozen_string_literal: false
diff --git a/test/rubygems/simple_gem.rb b/test/rubygems/simple_gem.rb
index c40002e2303ee3..a6af71eef409b4 100644
--- a/test/rubygems/simple_gem.rb
+++ b/test/rubygems/simple_gem.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 SIMPLE_GEM = <<-GEMDATA
         MD5SUM = "989bf34a1cbecd52e0ea66b662b3a405"
         if $0 == __FILE__
diff --git a/test/rubygems/test_bundled_ca.rb b/test/rubygems/test_bundled_ca.rb
index 9b2b978af16a31..0f8b6bd6a922cd 100644
--- a/test/rubygems/test_bundled_ca.rb
+++ b/test/rubygems/test_bundled_ca.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'net/https'
 require 'rubygems/request'
diff --git a/test/rubygems/test_config.rb b/test/rubygems/test_config.rb
index fb6d05c986205a..207085b62df8ee 100644
--- a/test/rubygems/test_config.rb
+++ b/test/rubygems/test_config.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems'
 
diff --git a/test/rubygems/test_deprecate.rb b/test/rubygems/test_deprecate.rb
index ed4e9aa5ffba9a..a29b565859cf97 100644
--- a/test/rubygems/test_deprecate.rb
+++ b/test/rubygems/test_deprecate.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 # require 'rubygems/builder'
 # require 'rubygems/package'
diff --git a/test/rubygems/test_gem.rb b/test/rubygems/test_gem.rb
index 1bcff8c2ff74bc..75ec9df06e4031 100644
--- a/test/rubygems/test_gem.rb
+++ b/test/rubygems/test_gem.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems'
 require 'rubygems/command'
diff --git a/test/rubygems/test_gem_available_set.rb b/test/rubygems/test_gem_available_set.rb
index 8b01112c11b399..85551f02726996 100644
--- a/test/rubygems/test_gem_available_set.rb
+++ b/test/rubygems/test_gem_available_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/available_set'
 require 'rubygems/security'
diff --git a/test/rubygems/test_gem_command.rb b/test/rubygems/test_gem_command.rb
index 48cbc98d8c44c8..5c1c0718eccbb7 100644
--- a/test/rubygems/test_gem_command.rb
+++ b/test/rubygems/test_gem_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/command'
 
diff --git a/test/rubygems/test_gem_command_manager.rb b/test/rubygems/test_gem_command_manager.rb
index f6433c5cc34253..fd25750c28a181 100644
--- a/test/rubygems/test_gem_command_manager.rb
+++ b/test/rubygems/test_gem_command_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/command_manager'
 
diff --git a/test/rubygems/test_gem_commands_build_command.rb b/test/rubygems/test_gem_commands_build_command.rb
index 5f870c07659e37..1fb80e1ddac9d9 100644
--- a/test/rubygems/test_gem_commands_build_command.rb
+++ b/test/rubygems/test_gem_commands_build_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/build_command'
 require 'rubygems/package'
diff --git a/test/rubygems/test_gem_commands_cert_command.rb b/test/rubygems/test_gem_commands_cert_command.rb
index 4c1dcc25c040f1..51793272115301 100644
--- a/test/rubygems/test_gem_commands_cert_command.rb
+++ b/test/rubygems/test_gem_commands_cert_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/cert_command'
 require 'rubygems/fix_openssl_warnings' if RUBY_VERSION < "1.9"
diff --git a/test/rubygems/test_gem_commands_check_command.rb b/test/rubygems/test_gem_commands_check_command.rb
index 67db6a32066577..6b76349fbeca86 100644
--- a/test/rubygems/test_gem_commands_check_command.rb
+++ b/test/rubygems/test_gem_commands_check_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/check_command'
 
diff --git a/test/rubygems/test_gem_commands_cleanup_command.rb b/test/rubygems/test_gem_commands_cleanup_command.rb
index e8ad35fe8e7d81..4a6dae8ae5ce79 100644
--- a/test/rubygems/test_gem_commands_cleanup_command.rb
+++ b/test/rubygems/test_gem_commands_cleanup_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/cleanup_command'
 require 'rubygems/installer'
diff --git a/test/rubygems/test_gem_commands_contents_command.rb b/test/rubygems/test_gem_commands_contents_command.rb
index ae8e49fdc318b7..ae02503524b298 100644
--- a/test/rubygems/test_gem_commands_contents_command.rb
+++ b/test/rubygems/test_gem_commands_contents_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/contents_command'
 
diff --git a/test/rubygems/test_gem_commands_dependency_command.rb b/test/rubygems/test_gem_commands_dependency_command.rb
index 1409162cece815..058b9a893ffa08 100644
--- a/test/rubygems/test_gem_commands_dependency_command.rb
+++ b/test/rubygems/test_gem_commands_dependency_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/dependency_command'
 
diff --git a/test/rubygems/test_gem_commands_environment_command.rb b/test/rubygems/test_gem_commands_environment_command.rb
index 81ff55d357a4c7..2def4175fe49c8 100644
--- a/test/rubygems/test_gem_commands_environment_command.rb
+++ b/test/rubygems/test_gem_commands_environment_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/environment_command'
 
diff --git a/test/rubygems/test_gem_commands_fetch_command.rb b/test/rubygems/test_gem_commands_fetch_command.rb
index c452e79f14740a..4a57b93f5043eb 100644
--- a/test/rubygems/test_gem_commands_fetch_command.rb
+++ b/test/rubygems/test_gem_commands_fetch_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/package'
 require 'rubygems/security'
diff --git a/test/rubygems/test_gem_commands_generate_index_command.rb b/test/rubygems/test_gem_commands_generate_index_command.rb
index 2e478d9c9e45bf..1c7213983e299e 100644
--- a/test/rubygems/test_gem_commands_generate_index_command.rb
+++ b/test/rubygems/test_gem_commands_generate_index_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/indexer'
 require 'rubygems/commands/generate_index_command'
diff --git a/test/rubygems/test_gem_commands_help_command.rb b/test/rubygems/test_gem_commands_help_command.rb
index bed60958278696..36512cb642f544 100644
--- a/test/rubygems/test_gem_commands_help_command.rb
+++ b/test/rubygems/test_gem_commands_help_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rubygems"
 require "rubygems/test_case"
 require "rubygems/commands/help_command"
diff --git a/test/rubygems/test_gem_commands_install_command.rb b/test/rubygems/test_gem_commands_install_command.rb
index c12b17e613ef3b..b8ddc97d7d2652 100644
--- a/test/rubygems/test_gem_commands_install_command.rb
+++ b/test/rubygems/test_gem_commands_install_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/install_command'
 require 'rubygems/request_set'
diff --git a/test/rubygems/test_gem_commands_list_command.rb b/test/rubygems/test_gem_commands_list_command.rb
index b03f166e1bb4cd..67e5980576e4d6 100644
--- a/test/rubygems/test_gem_commands_list_command.rb
+++ b/test/rubygems/test_gem_commands_list_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/list_command'
 
diff --git a/test/rubygems/test_gem_commands_lock_command.rb b/test/rubygems/test_gem_commands_lock_command.rb
index 8f30b7f2ccf260..ae85c4653f8843 100644
--- a/test/rubygems/test_gem_commands_lock_command.rb
+++ b/test/rubygems/test_gem_commands_lock_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/lock_command'
 
diff --git a/test/rubygems/test_gem_commands_mirror.rb b/test/rubygems/test_gem_commands_mirror.rb
index 3b01ab36451bff..c20ed3b4c8d88d 100644
--- a/test/rubygems/test_gem_commands_mirror.rb
+++ b/test/rubygems/test_gem_commands_mirror.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/mirror_command'
 
diff --git a/test/rubygems/test_gem_commands_open_command.rb b/test/rubygems/test_gem_commands_open_command.rb
index c1c76f95c997db..e342c2c60cb1db 100644
--- a/test/rubygems/test_gem_commands_open_command.rb
+++ b/test/rubygems/test_gem_commands_open_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/open_command'
 
diff --git a/test/rubygems/test_gem_commands_outdated_command.rb b/test/rubygems/test_gem_commands_outdated_command.rb
index 1bc5acc1f4e6ed..ee48d070fbae8d 100644
--- a/test/rubygems/test_gem_commands_outdated_command.rb
+++ b/test/rubygems/test_gem_commands_outdated_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/outdated_command'
 
diff --git a/test/rubygems/test_gem_commands_owner_command.rb b/test/rubygems/test_gem_commands_owner_command.rb
index 5d7b66137e7343..6d8275227f94bf 100644
--- a/test/rubygems/test_gem_commands_owner_command.rb
+++ b/test/rubygems/test_gem_commands_owner_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/owner_command'
 
diff --git a/test/rubygems/test_gem_commands_pristine_command.rb b/test/rubygems/test_gem_commands_pristine_command.rb
index b12fba511da934..1160c37b619b5c 100644
--- a/test/rubygems/test_gem_commands_pristine_command.rb
+++ b/test/rubygems/test_gem_commands_pristine_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/pristine_command'
 
diff --git a/test/rubygems/test_gem_commands_push_command.rb b/test/rubygems/test_gem_commands_push_command.rb
index 7d3d2efb8860fb..06967e09903e2a 100644
--- a/test/rubygems/test_gem_commands_push_command.rb
+++ b/test/rubygems/test_gem_commands_push_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/push_command'
 
diff --git a/test/rubygems/test_gem_commands_query_command.rb b/test/rubygems/test_gem_commands_query_command.rb
index 50cedbb50ea92e..da777312f0f680 100644
--- a/test/rubygems/test_gem_commands_query_command.rb
+++ b/test/rubygems/test_gem_commands_query_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/query_command'
 
diff --git a/test/rubygems/test_gem_commands_search_command.rb b/test/rubygems/test_gem_commands_search_command.rb
index fb8debc245a726..1bb3eb90f234dd 100644
--- a/test/rubygems/test_gem_commands_search_command.rb
+++ b/test/rubygems/test_gem_commands_search_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/search_command'
 
diff --git a/test/rubygems/test_gem_commands_server_command.rb b/test/rubygems/test_gem_commands_server_command.rb
index d0782f9a941261..41866670615b4e 100644
--- a/test/rubygems/test_gem_commands_server_command.rb
+++ b/test/rubygems/test_gem_commands_server_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/server_command'
 
diff --git a/test/rubygems/test_gem_commands_setup_command.rb b/test/rubygems/test_gem_commands_setup_command.rb
index 974c157a183e4b..9748db79d52928 100644
--- a/test/rubygems/test_gem_commands_setup_command.rb
+++ b/test/rubygems/test_gem_commands_setup_command.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 
 require 'rubygems/test_case'
 require 'rubygems/commands/setup_command'
diff --git a/test/rubygems/test_gem_commands_sources_command.rb b/test/rubygems/test_gem_commands_sources_command.rb
index 8ee0fd3cb78e42..f7af9d59629283 100644
--- a/test/rubygems/test_gem_commands_sources_command.rb
+++ b/test/rubygems/test_gem_commands_sources_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/sources_command'
 
diff --git a/test/rubygems/test_gem_commands_specification_command.rb b/test/rubygems/test_gem_commands_specification_command.rb
index ccc2dbbae9729c..4759ba47c05710 100644
--- a/test/rubygems/test_gem_commands_specification_command.rb
+++ b/test/rubygems/test_gem_commands_specification_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/specification_command'
 
diff --git a/test/rubygems/test_gem_commands_stale_command.rb b/test/rubygems/test_gem_commands_stale_command.rb
index 69b1e29e2df9a5..c7b23574dac0fc 100644
--- a/test/rubygems/test_gem_commands_stale_command.rb
+++ b/test/rubygems/test_gem_commands_stale_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/stale_command'
 
diff --git a/test/rubygems/test_gem_commands_uninstall_command.rb b/test/rubygems/test_gem_commands_uninstall_command.rb
index 8e90325f1f1963..b001b7f2a8d592 100644
--- a/test/rubygems/test_gem_commands_uninstall_command.rb
+++ b/test/rubygems/test_gem_commands_uninstall_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/installer_test_case'
 require 'rubygems/commands/uninstall_command'
 
diff --git a/test/rubygems/test_gem_commands_unpack_command.rb b/test/rubygems/test_gem_commands_unpack_command.rb
index 05002f8832d387..1420c8fa60bfc2 100644
--- a/test/rubygems/test_gem_commands_unpack_command.rb
+++ b/test/rubygems/test_gem_commands_unpack_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/unpack_command'
 
diff --git a/test/rubygems/test_gem_commands_update_command.rb b/test/rubygems/test_gem_commands_update_command.rb
index 03894d7590427e..a49cc3ace19ed4 100644
--- a/test/rubygems/test_gem_commands_update_command.rb
+++ b/test/rubygems/test_gem_commands_update_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/update_command'
 
diff --git a/test/rubygems/test_gem_commands_which_command.rb b/test/rubygems/test_gem_commands_which_command.rb
index 5c6afe93d1456e..2549579c842ca0 100644
--- a/test/rubygems/test_gem_commands_which_command.rb
+++ b/test/rubygems/test_gem_commands_which_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/which_command'
 
diff --git a/test/rubygems/test_gem_commands_yank_command.rb b/test/rubygems/test_gem_commands_yank_command.rb
index 469fd15bd9576c..49e8eda6e548a8 100644
--- a/test/rubygems/test_gem_commands_yank_command.rb
+++ b/test/rubygems/test_gem_commands_yank_command.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/commands/yank_command'
 
diff --git a/test/rubygems/test_gem_config_file.rb b/test/rubygems/test_gem_config_file.rb
index 3ababfbbfdf4ba..6ed240f306d5c5 100644
--- a/test/rubygems/test_gem_config_file.rb
+++ b/test/rubygems/test_gem_config_file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/config_file'
 
diff --git a/test/rubygems/test_gem_dependency.rb b/test/rubygems/test_gem_dependency.rb
index 4c27ce73008558..dcb722687b59fa 100644
--- a/test/rubygems/test_gem_dependency.rb
+++ b/test/rubygems/test_gem_dependency.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/dependency'
 
diff --git a/test/rubygems/test_gem_dependency_installer.rb b/test/rubygems/test_gem_dependency_installer.rb
index 03bcd04bc030be..dfa9494a493166 100644
--- a/test/rubygems/test_gem_dependency_installer.rb
+++ b/test/rubygems/test_gem_dependency_installer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/dependency_installer'
 require 'rubygems/security'
diff --git a/test/rubygems/test_gem_dependency_list.rb b/test/rubygems/test_gem_dependency_list.rb
index d25359e84b187d..8c63206f9004be 100644
--- a/test/rubygems/test_gem_dependency_list.rb
+++ b/test/rubygems/test_gem_dependency_list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/dependency_list'
 
diff --git a/test/rubygems/test_gem_dependency_resolution_error.rb b/test/rubygems/test_gem_dependency_resolution_error.rb
index 0442082e6a3079..bae561c8046b05 100644
--- a/test/rubygems/test_gem_dependency_resolution_error.rb
+++ b/test/rubygems/test_gem_dependency_resolution_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemDependencyResolutionError < Gem::TestCase
diff --git a/test/rubygems/test_gem_doctor.rb b/test/rubygems/test_gem_doctor.rb
index 1097528e1894ef..5eb190377de22c 100644
--- a/test/rubygems/test_gem_doctor.rb
+++ b/test/rubygems/test_gem_doctor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/doctor'
 
diff --git a/test/rubygems/test_gem_ext_builder.rb b/test/rubygems/test_gem_ext_builder.rb
index 02c7593628e3bb..e8cc5aa57cb7f7 100644
--- a/test/rubygems/test_gem_ext_builder.rb
+++ b/test/rubygems/test_gem_ext_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/ext'
 require 'rubygems/installer'
diff --git a/test/rubygems/test_gem_ext_cmake_builder.rb b/test/rubygems/test_gem_ext_cmake_builder.rb
index a36be476befe11..7a296ccfd5ccd1 100644
--- a/test/rubygems/test_gem_ext_cmake_builder.rb
+++ b/test/rubygems/test_gem_ext_cmake_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/ext'
 
diff --git a/test/rubygems/test_gem_ext_configure_builder.rb b/test/rubygems/test_gem_ext_configure_builder.rb
index 610d60a9204466..6cbe8ba5604b77 100644
--- a/test/rubygems/test_gem_ext_configure_builder.rb
+++ b/test/rubygems/test_gem_ext_configure_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/ext'
 
diff --git a/test/rubygems/test_gem_ext_ext_conf_builder.rb b/test/rubygems/test_gem_ext_ext_conf_builder.rb
index 689734ac374f6e..d71529b61b61c5 100644
--- a/test/rubygems/test_gem_ext_ext_conf_builder.rb
+++ b/test/rubygems/test_gem_ext_ext_conf_builder.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 
 require 'rubygems/test_case'
 require 'rubygems/ext'
diff --git a/test/rubygems/test_gem_ext_rake_builder.rb b/test/rubygems/test_gem_ext_rake_builder.rb
index 0f4789a68f7fb2..8eaa3f43c3fa1d 100644
--- a/test/rubygems/test_gem_ext_rake_builder.rb
+++ b/test/rubygems/test_gem_ext_rake_builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/ext'
 
diff --git a/test/rubygems/test_gem_gem_runner.rb b/test/rubygems/test_gem_gem_runner.rb
index 85ff72534593f7..0ca66c90784fe9 100644
--- a/test/rubygems/test_gem_gem_runner.rb
+++ b/test/rubygems/test_gem_gem_runner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/gem_runner'
 
diff --git a/test/rubygems/test_gem_gemcutter_utilities.rb b/test/rubygems/test_gem_gemcutter_utilities.rb
index c117c8f82647a5..79be8b047741dc 100644
--- a/test/rubygems/test_gem_gemcutter_utilities.rb
+++ b/test/rubygems/test_gem_gemcutter_utilities.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems'
 require 'rubygems/command'
diff --git a/test/rubygems/test_gem_impossible_dependencies_error.rb b/test/rubygems/test_gem_impossible_dependencies_error.rb
index 9c9825ca9ab046..6a6c9c04cfac1d 100644
--- a/test/rubygems/test_gem_impossible_dependencies_error.rb
+++ b/test/rubygems/test_gem_impossible_dependencies_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemImpossibleDependenciesError < Gem::TestCase
diff --git a/test/rubygems/test_gem_indexer.rb b/test/rubygems/test_gem_indexer.rb
index 9622cd1abbd967..1f255ff715a73e 100644
--- a/test/rubygems/test_gem_indexer.rb
+++ b/test/rubygems/test_gem_indexer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/indexer'
 
diff --git a/test/rubygems/test_gem_install_update_options.rb b/test/rubygems/test_gem_install_update_options.rb
index e7dc52a63c249c..d81fa86e9cfa1d 100644
--- a/test/rubygems/test_gem_install_update_options.rb
+++ b/test/rubygems/test_gem_install_update_options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/installer_test_case'
 require 'rubygems/install_update_options'
 require 'rubygems/command'
diff --git a/test/rubygems/test_gem_installer.rb b/test/rubygems/test_gem_installer.rb
index 2e5ac6ab76ac70..129c235abb2a24 100644
--- a/test/rubygems/test_gem_installer.rb
+++ b/test/rubygems/test_gem_installer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/installer_test_case'
 
 class TestGemInstaller < Gem::InstallerTestCase
diff --git a/test/rubygems/test_gem_local_remote_options.rb b/test/rubygems/test_gem_local_remote_options.rb
index 1a0338bfe1a471..4e02e2adebdc1b 100644
--- a/test/rubygems/test_gem_local_remote_options.rb
+++ b/test/rubygems/test_gem_local_remote_options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/local_remote_options'
 require 'rubygems/command'
diff --git a/test/rubygems/test_gem_name_tuple.rb b/test/rubygems/test_gem_name_tuple.rb
index 38320f75909caa..250a16799466cc 100644
--- a/test/rubygems/test_gem_name_tuple.rb
+++ b/test/rubygems/test_gem_name_tuple.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/name_tuple'
 
diff --git a/test/rubygems/test_gem_package.rb b/test/rubygems/test_gem_package.rb
index bbb036d8497c03..7848bc2428e771 100644
--- a/test/rubygems/test_gem_package.rb
+++ b/test/rubygems/test_gem_package.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 
 require 'rubygems/package/tar_test_case'
 require 'rubygems/simple_gem'
diff --git a/test/rubygems/test_gem_package_old.rb b/test/rubygems/test_gem_package_old.rb
index 6236dbbaf2544c..ddc4e01abbec0e 100644
--- a/test/rubygems/test_gem_package_old.rb
+++ b/test/rubygems/test_gem_package_old.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/simple_gem'
 
diff --git a/test/rubygems/test_gem_package_tar_header.rb b/test/rubygems/test_gem_package_tar_header.rb
index 9977e282a1aab5..f1ece66aa70251 100644
--- a/test/rubygems/test_gem_package_tar_header.rb
+++ b/test/rubygems/test_gem_package_tar_header.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/package/tar_test_case'
 require 'rubygems/package'
 
diff --git a/test/rubygems/test_gem_package_tar_reader.rb b/test/rubygems/test_gem_package_tar_reader.rb
index aa45417b0dc2a2..2b6b81e287c408 100644
--- a/test/rubygems/test_gem_package_tar_reader.rb
+++ b/test/rubygems/test_gem_package_tar_reader.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/package/tar_test_case'
 require 'rubygems/package'
 
diff --git a/test/rubygems/test_gem_package_tar_reader_entry.rb b/test/rubygems/test_gem_package_tar_reader_entry.rb
index 335601b5ca4569..1138436f00936f 100644
--- a/test/rubygems/test_gem_package_tar_reader_entry.rb
+++ b/test/rubygems/test_gem_package_tar_reader_entry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/package/tar_test_case'
 require 'rubygems/package'
 
diff --git a/test/rubygems/test_gem_package_tar_writer.rb b/test/rubygems/test_gem_package_tar_writer.rb
index dac9a54b46b16f..29b7fdb3b9868c 100644
--- a/test/rubygems/test_gem_package_tar_writer.rb
+++ b/test/rubygems/test_gem_package_tar_writer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/package/tar_test_case'
 require 'rubygems/package/tar_writer'
 require 'minitest/mock'
diff --git a/test/rubygems/test_gem_package_task.rb b/test/rubygems/test_gem_package_task.rb
index 5b83fc4e3c5e4e..f93fc4cc544b10 100644
--- a/test/rubygems/test_gem_package_task.rb
+++ b/test/rubygems/test_gem_package_task.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems'
 begin
diff --git a/test/rubygems/test_gem_path_support.rb b/test/rubygems/test_gem_path_support.rb
index 879cc98b5fcb76..e9e22d0fdc1f52 100644
--- a/test/rubygems/test_gem_path_support.rb
+++ b/test/rubygems/test_gem_path_support.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems'
 require 'fileutils'
diff --git a/test/rubygems/test_gem_platform.rb b/test/rubygems/test_gem_platform.rb
index 164977224ce65a..9636afc77fb997 100644
--- a/test/rubygems/test_gem_platform.rb
+++ b/test/rubygems/test_gem_platform.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/platform'
 require 'rbconfig'
diff --git a/test/rubygems/test_gem_rdoc.rb b/test/rubygems/test_gem_rdoc.rb
index 3ff06fe0d557d4..69d4e2071fbabc 100644
--- a/test/rubygems/test_gem_rdoc.rb
+++ b/test/rubygems/test_gem_rdoc.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems'
 require 'rubygems/test_case'
 require 'rubygems/rdoc'
diff --git a/test/rubygems/test_gem_remote_fetcher.rb b/test/rubygems/test_gem_remote_fetcher.rb
index 5598e46b2667ff..8b469214019ab0 100644
--- a/test/rubygems/test_gem_remote_fetcher.rb
+++ b/test/rubygems/test_gem_remote_fetcher.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 require 'webrick'
diff --git a/test/rubygems/test_gem_request.rb b/test/rubygems/test_gem_request.rb
index 397f575f37c851..98cdc80af4e7ed 100644
--- a/test/rubygems/test_gem_request.rb
+++ b/test/rubygems/test_gem_request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/request'
 require 'ostruct'
diff --git a/test/rubygems/test_gem_request_connection_pools.rb b/test/rubygems/test_gem_request_connection_pools.rb
index 1944a4f3516b6e..30f273029be861 100644
--- a/test/rubygems/test_gem_request_connection_pools.rb
+++ b/test/rubygems/test_gem_request_connection_pools.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/request'
 require 'timeout'
diff --git a/test/rubygems/test_gem_request_set.rb b/test/rubygems/test_gem_request_set.rb
index 8afab65356ea2f..136990264ee5a0 100644
--- a/test/rubygems/test_gem_request_set.rb
+++ b/test/rubygems/test_gem_request_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/request_set'
 
diff --git a/test/rubygems/test_gem_request_set_gem_dependency_api.rb b/test/rubygems/test_gem_request_set_gem_dependency_api.rb
index 5d7f2d1296ab08..6bbe8a6d4fed01 100644
--- a/test/rubygems/test_gem_request_set_gem_dependency_api.rb
+++ b/test/rubygems/test_gem_request_set_gem_dependency_api.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/request_set'
 
diff --git a/test/rubygems/test_gem_request_set_lockfile.rb b/test/rubygems/test_gem_request_set_lockfile.rb
index 3b85e256f27c85..3d30a9aa63e1ac 100644
--- a/test/rubygems/test_gem_request_set_lockfile.rb
+++ b/test/rubygems/test_gem_request_set_lockfile.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/request_set'
 require 'rubygems/request_set/lockfile'
diff --git a/test/rubygems/test_gem_request_set_lockfile_parser.rb b/test/rubygems/test_gem_request_set_lockfile_parser.rb
index c5b2b19c0edc75..afb92e28402f67 100644
--- a/test/rubygems/test_gem_request_set_lockfile_parser.rb
+++ b/test/rubygems/test_gem_request_set_lockfile_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/request_set'
 require 'rubygems/request_set/lockfile'
diff --git a/test/rubygems/test_gem_request_set_lockfile_tokenizer.rb b/test/rubygems/test_gem_request_set_lockfile_tokenizer.rb
index b11858361e7f0d..230d6118bf0b0d 100644
--- a/test/rubygems/test_gem_request_set_lockfile_tokenizer.rb
+++ b/test/rubygems/test_gem_request_set_lockfile_tokenizer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/request_set'
 require 'rubygems/request_set/lockfile'
diff --git a/test/rubygems/test_gem_requirement.rb b/test/rubygems/test_gem_requirement.rb
index 234edb4ec358fe..f608d9458d75e6 100644
--- a/test/rubygems/test_gem_requirement.rb
+++ b/test/rubygems/test_gem_requirement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require "rubygems/requirement"
 
diff --git a/test/rubygems/test_gem_resolver.rb b/test/rubygems/test_gem_resolver.rb
index a944a69d9aabc3..54e48178083c5a 100644
--- a/test/rubygems/test_gem_resolver.rb
+++ b/test/rubygems/test_gem_resolver.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolver < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_activation_request.rb b/test/rubygems/test_gem_resolver_activation_request.rb
index c9163e25dec9f9..3456c427228a32 100644
--- a/test/rubygems/test_gem_resolver_activation_request.rb
+++ b/test/rubygems/test_gem_resolver_activation_request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverActivationRequest < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_api_set.rb b/test/rubygems/test_gem_resolver_api_set.rb
index 4ae54d71b33f56..beb580f3470955 100644
--- a/test/rubygems/test_gem_resolver_api_set.rb
+++ b/test/rubygems/test_gem_resolver_api_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverAPISet < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_api_specification.rb b/test/rubygems/test_gem_resolver_api_specification.rb
index dfa61e98a043be..f4335c74f73075 100644
--- a/test/rubygems/test_gem_resolver_api_specification.rb
+++ b/test/rubygems/test_gem_resolver_api_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverAPISpecification < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_best_set.rb b/test/rubygems/test_gem_resolver_best_set.rb
index 055438c89bb59a..db2cbea1011c74 100644
--- a/test/rubygems/test_gem_resolver_best_set.rb
+++ b/test/rubygems/test_gem_resolver_best_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverBestSet < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_composed_set.rb b/test/rubygems/test_gem_resolver_composed_set.rb
index f8455e1aa477b0..6032bcf7e2c666 100644
--- a/test/rubygems/test_gem_resolver_composed_set.rb
+++ b/test/rubygems/test_gem_resolver_composed_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverComposedSet < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_conflict.rb b/test/rubygems/test_gem_resolver_conflict.rb
index 0cef0cad2a5753..d4d81fab6c9e21 100644
--- a/test/rubygems/test_gem_resolver_conflict.rb
+++ b/test/rubygems/test_gem_resolver_conflict.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverConflict < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_dependency_request.rb b/test/rubygems/test_gem_resolver_dependency_request.rb
index 0665883971fb4a..2587c645db60fc 100644
--- a/test/rubygems/test_gem_resolver_dependency_request.rb
+++ b/test/rubygems/test_gem_resolver_dependency_request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverDependencyRequest < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_git_set.rb b/test/rubygems/test_gem_resolver_git_set.rb
index 3659193456285e..c6fca20905903f 100644
--- a/test/rubygems/test_gem_resolver_git_set.rb
+++ b/test/rubygems/test_gem_resolver_git_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverGitSet < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_git_specification.rb b/test/rubygems/test_gem_resolver_git_specification.rb
index 7ab297923cf5b9..f484b1c7797f05 100644
--- a/test/rubygems/test_gem_resolver_git_specification.rb
+++ b/test/rubygems/test_gem_resolver_git_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/installer'
 
diff --git a/test/rubygems/test_gem_resolver_index_set.rb b/test/rubygems/test_gem_resolver_index_set.rb
index 04ef8844c193a0..abac704712e988 100644
--- a/test/rubygems/test_gem_resolver_index_set.rb
+++ b/test/rubygems/test_gem_resolver_index_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverIndexSet < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_index_specification.rb b/test/rubygems/test_gem_resolver_index_specification.rb
index e52f9c7fc681ce..6e9605218d64b8 100644
--- a/test/rubygems/test_gem_resolver_index_specification.rb
+++ b/test/rubygems/test_gem_resolver_index_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/available_set'
 
diff --git a/test/rubygems/test_gem_resolver_installed_specification.rb b/test/rubygems/test_gem_resolver_installed_specification.rb
index d52876f0301051..f24d9ec22394ef 100644
--- a/test/rubygems/test_gem_resolver_installed_specification.rb
+++ b/test/rubygems/test_gem_resolver_installed_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverInstalledSpecification < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_installer_set.rb b/test/rubygems/test_gem_resolver_installer_set.rb
index 039582e6900fcc..a8627ed1419996 100644
--- a/test/rubygems/test_gem_resolver_installer_set.rb
+++ b/test/rubygems/test_gem_resolver_installer_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverInstallerSet < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_local_specification.rb b/test/rubygems/test_gem_resolver_local_specification.rb
index fc3175a3f712f2..8eac442171125c 100644
--- a/test/rubygems/test_gem_resolver_local_specification.rb
+++ b/test/rubygems/test_gem_resolver_local_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/available_set'
 
diff --git a/test/rubygems/test_gem_resolver_lock_set.rb b/test/rubygems/test_gem_resolver_lock_set.rb
index fdcb8ffa986c98..745b5dd85bd466 100644
--- a/test/rubygems/test_gem_resolver_lock_set.rb
+++ b/test/rubygems/test_gem_resolver_lock_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverLockSet < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_lock_specification.rb b/test/rubygems/test_gem_resolver_lock_specification.rb
index 93240356eff314..eabfec0a0da7c2 100644
--- a/test/rubygems/test_gem_resolver_lock_specification.rb
+++ b/test/rubygems/test_gem_resolver_lock_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/installer'
 require 'rubygems/resolver'
diff --git a/test/rubygems/test_gem_resolver_requirement_list.rb b/test/rubygems/test_gem_resolver_requirement_list.rb
index fd9dccb70f7166..c7192475b8a636 100644
--- a/test/rubygems/test_gem_resolver_requirement_list.rb
+++ b/test/rubygems/test_gem_resolver_requirement_list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverRequirementList < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_specification.rb b/test/rubygems/test_gem_resolver_specification.rb
index e1ec68a22c46ea..73bda1f989649b 100644
--- a/test/rubygems/test_gem_resolver_specification.rb
+++ b/test/rubygems/test_gem_resolver_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverSpecification < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_vendor_set.rb b/test/rubygems/test_gem_resolver_vendor_set.rb
index 618e251de24fd9..6bb282ad044e87 100644
--- a/test/rubygems/test_gem_resolver_vendor_set.rb
+++ b/test/rubygems/test_gem_resolver_vendor_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverVendorSet < Gem::TestCase
diff --git a/test/rubygems/test_gem_resolver_vendor_specification.rb b/test/rubygems/test_gem_resolver_vendor_specification.rb
index 3d94cfed00d58a..4d72e3481018af 100644
--- a/test/rubygems/test_gem_resolver_vendor_specification.rb
+++ b/test/rubygems/test_gem_resolver_vendor_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemResolverVendorSpecification < Gem::TestCase
diff --git a/test/rubygems/test_gem_security.rb b/test/rubygems/test_gem_security.rb
index b8747b79c3ec2a..d653d2c262631a 100644
--- a/test/rubygems/test_gem_security.rb
+++ b/test/rubygems/test_gem_security.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/security'
 require 'rubygems/fix_openssl_warnings' if RUBY_VERSION < "1.9"
diff --git a/test/rubygems/test_gem_security_policy.rb b/test/rubygems/test_gem_security_policy.rb
index d708306e79f8ed..b911d528df02c5 100644
--- a/test/rubygems/test_gem_security_policy.rb
+++ b/test/rubygems/test_gem_security_policy.rb
@@ -1,4 +1,5 @@
 # coding: UTF-8
+# frozen_string_literal: false
 
 require 'rubygems/test_case'
 
diff --git a/test/rubygems/test_gem_security_signer.rb b/test/rubygems/test_gem_security_signer.rb
index f077a46413e073..f473d406045eae 100644
--- a/test/rubygems/test_gem_security_signer.rb
+++ b/test/rubygems/test_gem_security_signer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 unless defined?(OpenSSL::SSL) then
diff --git a/test/rubygems/test_gem_security_trust_dir.rb b/test/rubygems/test_gem_security_trust_dir.rb
index 475db2e79021dc..387c0925b62efb 100644
--- a/test/rubygems/test_gem_security_trust_dir.rb
+++ b/test/rubygems/test_gem_security_trust_dir.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 unless defined?(OpenSSL::SSL) then
diff --git a/test/rubygems/test_gem_server.rb b/test/rubygems/test_gem_server.rb
index 98a703c9d22ea7..0ebc7d573a613e 100644
--- a/test/rubygems/test_gem_server.rb
+++ b/test/rubygems/test_gem_server.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/server'
 require 'stringio'
diff --git a/test/rubygems/test_gem_silent_ui.rb b/test/rubygems/test_gem_silent_ui.rb
index 01ff79d828af7c..0caf362d4605b5 100644
--- a/test/rubygems/test_gem_silent_ui.rb
+++ b/test/rubygems/test_gem_silent_ui.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/user_interaction'
 require 'timeout'
diff --git a/test/rubygems/test_gem_source.rb b/test/rubygems/test_gem_source.rb
index 7d23eeea5e4f64..d4a8a0142dccf4 100644
--- a/test/rubygems/test_gem_source.rb
+++ b/test/rubygems/test_gem_source.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/source'
 require 'rubygems/indexer'
diff --git a/test/rubygems/test_gem_source_fetch_problem.rb b/test/rubygems/test_gem_source_fetch_problem.rb
index e8d4785a31ca79..34ac743da7d8f3 100644
--- a/test/rubygems/test_gem_source_fetch_problem.rb
+++ b/test/rubygems/test_gem_source_fetch_problem.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemSourceFetchProblem < Gem::TestCase
diff --git a/test/rubygems/test_gem_source_git.rb b/test/rubygems/test_gem_source_git.rb
index 7e5bccacaec832..ea86d6657be67c 100644
--- a/test/rubygems/test_gem_source_git.rb
+++ b/test/rubygems/test_gem_source_git.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/source'
 
diff --git a/test/rubygems/test_gem_source_installed.rb b/test/rubygems/test_gem_source_installed.rb
index 9eaddf72fdd4f1..0337036410b09c 100644
--- a/test/rubygems/test_gem_source_installed.rb
+++ b/test/rubygems/test_gem_source_installed.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/source'
 
diff --git a/test/rubygems/test_gem_source_list.rb b/test/rubygems/test_gem_source_list.rb
index 43db204a50f34a..23ae749affee33 100644
--- a/test/rubygems/test_gem_source_list.rb
+++ b/test/rubygems/test_gem_source_list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/source_list'
 require 'rubygems/test_case'
 
diff --git a/test/rubygems/test_gem_source_local.rb b/test/rubygems/test_gem_source_local.rb
index 19e1c4b7591ab3..05c4c7e57cba32 100644
--- a/test/rubygems/test_gem_source_local.rb
+++ b/test/rubygems/test_gem_source_local.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/source'
 
diff --git a/test/rubygems/test_gem_source_lock.rb b/test/rubygems/test_gem_source_lock.rb
index 23f063da92464b..c5596d248b66b9 100644
--- a/test/rubygems/test_gem_source_lock.rb
+++ b/test/rubygems/test_gem_source_lock.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemSourceLock < Gem::TestCase
diff --git a/test/rubygems/test_gem_source_specific_file.rb b/test/rubygems/test_gem_source_specific_file.rb
index 12ef7f5b7c336c..a54260dfc64b2e 100644
--- a/test/rubygems/test_gem_source_specific_file.rb
+++ b/test/rubygems/test_gem_source_specific_file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/source'
 
diff --git a/test/rubygems/test_gem_source_vendor.rb b/test/rubygems/test_gem_source_vendor.rb
index 1d9ae35e84f385..f59e6a7fdf70a6 100644
--- a/test/rubygems/test_gem_source_vendor.rb
+++ b/test/rubygems/test_gem_source_vendor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/source'
 
diff --git a/test/rubygems/test_gem_spec_fetcher.rb b/test/rubygems/test_gem_spec_fetcher.rb
index 6ee1a52fc7c4f4..876094f9b767c6 100644
--- a/test/rubygems/test_gem_spec_fetcher.rb
+++ b/test/rubygems/test_gem_spec_fetcher.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/spec_fetcher'
 
diff --git a/test/rubygems/test_gem_specification.rb b/test/rubygems/test_gem_specification.rb
index 6c7ee6054a4f51..cfca49a18f8809 100644
--- a/test/rubygems/test_gem_specification.rb
+++ b/test/rubygems/test_gem_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'benchmark'
 require 'rubygems/test_case'
 require 'pathname'
diff --git a/test/rubygems/test_gem_stream_ui.rb b/test/rubygems/test_gem_stream_ui.rb
index bea187e8f36aa0..aa6b19f8be37f8 100644
--- a/test/rubygems/test_gem_stream_ui.rb
+++ b/test/rubygems/test_gem_stream_ui.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/user_interaction'
 require 'timeout'
diff --git a/test/rubygems/test_gem_stub_specification.rb b/test/rubygems/test_gem_stub_specification.rb
index 786a308556185a..5ffbc57a9a5460 100644
--- a/test/rubygems/test_gem_stub_specification.rb
+++ b/test/rubygems/test_gem_stub_specification.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "rubygems/test_case"
 require "rubygems/stub_specification"
 
diff --git a/test/rubygems/test_gem_text.rb b/test/rubygems/test_gem_text.rb
index 90f81fcd51242d..855e9ac09dbf04 100644
--- a/test/rubygems/test_gem_text.rb
+++ b/test/rubygems/test_gem_text.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require "rubygems/text"
 
diff --git a/test/rubygems/test_gem_uninstaller.rb b/test/rubygems/test_gem_uninstaller.rb
index c682f72c38229b..13cc6eb39ff34a 100644
--- a/test/rubygems/test_gem_uninstaller.rb
+++ b/test/rubygems/test_gem_uninstaller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/installer_test_case'
 require 'rubygems/uninstaller'
 
diff --git a/test/rubygems/test_gem_unsatisfiable_dependency_error.rb b/test/rubygems/test_gem_unsatisfiable_dependency_error.rb
index 6418c5d20e5278..c7aba3d54af89d 100644
--- a/test/rubygems/test_gem_unsatisfiable_dependency_error.rb
+++ b/test/rubygems/test_gem_unsatisfiable_dependency_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestGemUnsatisfiableDependencyError < Gem::TestCase
diff --git a/test/rubygems/test_gem_uri_formatter.rb b/test/rubygems/test_gem_uri_formatter.rb
index 628b7c54de9d38..036e7cd673a921 100644
--- a/test/rubygems/test_gem_uri_formatter.rb
+++ b/test/rubygems/test_gem_uri_formatter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/uri_formatter'
 
diff --git a/test/rubygems/test_gem_util.rb b/test/rubygems/test_gem_util.rb
index 2546262d7feea2..8b763f0ff1e6e5 100644
--- a/test/rubygems/test_gem_util.rb
+++ b/test/rubygems/test_gem_util.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/util'
 
diff --git a/test/rubygems/test_gem_validator.rb b/test/rubygems/test_gem_validator.rb
index 4af8b524e1971c..4770bdfb64872e 100644
--- a/test/rubygems/test_gem_validator.rb
+++ b/test/rubygems/test_gem_validator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require "rubygems/simple_gem"
 require 'rubygems/validator'
diff --git a/test/rubygems/test_gem_version.rb b/test/rubygems/test_gem_version.rb
index 5a65b5c9c7b506..ffe4d028f55535 100644
--- a/test/rubygems/test_gem_version.rb
+++ b/test/rubygems/test_gem_version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require "rubygems/version"
 
diff --git a/test/rubygems/test_gem_version_option.rb b/test/rubygems/test_gem_version_option.rb
index d6035ab80030a0..9af7c63bde0e3e 100644
--- a/test/rubygems/test_gem_version_option.rb
+++ b/test/rubygems/test_gem_version_option.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems/command'
 require 'rubygems/version_option'
diff --git a/test/rubygems/test_kernel.rb b/test/rubygems/test_kernel.rb
index ee8b2487971634..f78fe1d3177130 100644
--- a/test/rubygems/test_kernel.rb
+++ b/test/rubygems/test_kernel.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 
 class TestKernel < Gem::TestCase
diff --git a/test/rubygems/test_require.rb b/test/rubygems/test_require.rb
index ec6662f917c9d9..b0808f96d8f8fd 100644
--- a/test/rubygems/test_require.rb
+++ b/test/rubygems/test_require.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rubygems/test_case'
 require 'rubygems'
 
diff --git a/test/runner.rb b/test/runner.rb
index 13506e592ef416..1fe32fcfc8e03f 100644
--- a/test/runner.rb
+++ b/test/runner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rbconfig'
 
 src_testdir = File.dirname(File.realpath(__FILE__))
diff --git a/test/scanf/test_scanf.rb b/test/scanf/test_scanf.rb
index 93bb63b6aa0c3d..827eb2fc3bbcc3 100644
--- a/test/scanf/test_scanf.rb
+++ b/test/scanf/test_scanf.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $Id$
 #
 # scanf for Ruby
diff --git a/test/scanf/test_scanfblocks.rb b/test/scanf/test_scanfblocks.rb
index aea5033a54084a..1c2265a825a26c 100644
--- a/test/scanf/test_scanfblocks.rb
+++ b/test/scanf/test_scanfblocks.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $Id$
 #
 # scanf for Ruby
diff --git a/test/scanf/test_scanfio.rb b/test/scanf/test_scanfio.rb
index 969a8ad7731bae..cec8750aef599e 100644
--- a/test/scanf/test_scanfio.rb
+++ b/test/scanf/test_scanfio.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # $Id$
 #
 # scanf for Ruby
diff --git a/test/sdbm/test_sdbm.rb b/test/sdbm/test_sdbm.rb
index f415584fa2ce54..154bccebc4cb8f 100644
--- a/test/sdbm/test_sdbm.rb
+++ b/test/sdbm/test_sdbm.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 
diff --git a/test/shell/test_command_processor.rb b/test/shell/test_command_processor.rb
index 66e4244ad3a210..99fe1b222a82bf 100644
--- a/test/shell/test_command_processor.rb
+++ b/test/shell/test_command_processor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'shell'
 require 'tmpdir'
 
diff --git a/test/stringio/test_stringio.rb b/test/stringio/test_stringio.rb
index bd4a0f1a515f04..17ae9ab848594a 100644
--- a/test/stringio/test_stringio.rb
+++ b/test/stringio/test_stringio.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'stringio'
 require_relative '../ruby/ut_eof'
diff --git a/test/strscan/test_stringscanner.rb b/test/strscan/test_stringscanner.rb
index 260ab6c558678b..ee97e454febe27 100644
--- a/test/strscan/test_stringscanner.rb
+++ b/test/strscan/test_stringscanner.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 #
 # test/strscan/test_stringscanner.rb
 #
diff --git a/test/syslog/test_syslog_logger.rb b/test/syslog/test_syslog_logger.rb
index d1998a18ce1268..5e0cc765a9098c 100644
--- a/test/syslog/test_syslog_logger.rb
+++ b/test/syslog/test_syslog_logger.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 begin
diff --git a/test/test_abbrev.rb b/test/test_abbrev.rb
index f342c59e205b1d..be9b7d50051154 100644
--- a/test/test_abbrev.rb
+++ b/test/test_abbrev.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'abbrev'
 
diff --git a/test/test_cmath.rb b/test/test_cmath.rb
index 979082ae42b3fd..2752ce782c5e42 100644
--- a/test/test_cmath.rb
+++ b/test/test_cmath.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'cmath'
 
diff --git a/test/test_delegate.rb b/test/test_delegate.rb
index 6270cc61b6e45d..629d191fade9c2 100644
--- a/test/test_delegate.rb
+++ b/test/test_delegate.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'delegate'
 
diff --git a/test/test_find.rb b/test/test_find.rb
index 2fa81eb0b41ad4..d0e92067f1176e 100644
--- a/test/test_find.rb
+++ b/test/test_find.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'find'
 require 'tmpdir'
diff --git a/test/test_forwardable.rb b/test/test_forwardable.rb
index 6dd015e5a4092c..a3d03f438b87b5 100644
--- a/test/test_forwardable.rb
+++ b/test/test_forwardable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'forwardable'
 
diff --git a/test/test_ipaddr.rb b/test/test_ipaddr.rb
index 88b4a01bcbb667..b9209f72d9ba27 100644
--- a/test/test_ipaddr.rb
+++ b/test/test_ipaddr.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'ipaddr'
 
diff --git a/test/test_mathn.rb b/test/test_mathn.rb
index 8a482f3fed4953..aaf132ba88fa89 100644
--- a/test/test_mathn.rb
+++ b/test/test_mathn.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 # mathn redefines too much. It must be isolated to child processes.
diff --git a/test/test_mutex_m.rb b/test/test_mutex_m.rb
index a29f3f44b5a7d0..e31c086f0131c5 100644
--- a/test/test_mutex_m.rb
+++ b/test/test_mutex_m.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'thread'
 require 'mutex_m'
diff --git a/test/test_observer.rb b/test/test_observer.rb
index e2c159ad09f970..c2fa7280043d8a 100644
--- a/test/test_observer.rb
+++ b/test/test_observer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'observer'
 
diff --git a/test/test_prime.rb b/test/test_prime.rb
index f8abebc32300c1..b48ccae3194e32 100644
--- a/test/test_prime.rb
+++ b/test/test_prime.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'prime'
 require 'timeout'
diff --git a/test/test_pstore.rb b/test/test_pstore.rb
index e028ed68b4f9c5..e7fe4f1d1545e4 100644
--- a/test/test_pstore.rb
+++ b/test/test_pstore.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'pstore'
 require 'tmpdir'
diff --git a/test/test_pty.rb b/test/test_pty.rb
index 0ec4f967bdd0de..cedf00f9189c3d 100644
--- a/test/test_pty.rb
+++ b/test/test_pty.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'shellwords'
 require 'tmpdir'
diff --git a/test/test_rbconfig.rb b/test/test_rbconfig.rb
index 36204500bd7780..1bbf01b9a6863c 100644
--- a/test/test_rbconfig.rb
+++ b/test/test_rbconfig.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'rbconfig'
 require 'shellwords'
diff --git a/test/test_securerandom.rb b/test/test_securerandom.rb
index da48a3b341feff..515d05e6b2af70 100644
--- a/test/test_securerandom.rb
+++ b/test/test_securerandom.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'securerandom'
 require 'tempfile'
diff --git a/test/test_set.rb b/test/test_set.rb
index 66944f576f62fc..15c5a13d21c8ac 100644
--- a/test/test_set.rb
+++ b/test/test_set.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'set'
 
diff --git a/test/test_shellwords.rb b/test/test_shellwords.rb
index c160ed9d1ca3c8..2916d5dda63465 100644
--- a/test/test_shellwords.rb
+++ b/test/test_shellwords.rb
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: false
 require 'test/unit'
 require 'shellwords'
 
diff --git a/test/test_singleton.rb b/test/test_singleton.rb
index 36d49372c1e79c..b3c48bb5f5dbc7 100644
--- a/test/test_singleton.rb
+++ b/test/test_singleton.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'singleton'
 
diff --git a/test/test_syslog.rb b/test/test_syslog.rb
index 7f1f76fcb61a88..c66e5f5fb25408 100644
--- a/test/test_syslog.rb
+++ b/test/test_syslog.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # Please only run this test on machines reasonable for testing.
 # If in doubt, ask your admin.
 
diff --git a/test/test_tempfile.rb b/test/test_tempfile.rb
index bcd953554a4610..c8af2f5b4d2d75 100644
--- a/test/test_tempfile.rb
+++ b/test/test_tempfile.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tempfile'
 require 'thread'
diff --git a/test/test_timeout.rb b/test/test_timeout.rb
index 911ad8c2e0f7cd..94ae83e820272d 100644
--- a/test/test_timeout.rb
+++ b/test/test_timeout.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 require 'thread'
diff --git a/test/test_tmpdir.rb b/test/test_tmpdir.rb
index 842b2ded90737a..4fc4bca4d591aa 100644
--- a/test/test_tmpdir.rb
+++ b/test/test_tmpdir.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 
diff --git a/test/test_tracer.rb b/test/test_tracer.rb
index b4ed7fce9fdab8..6622b536631cf0 100644
--- a/test/test_tracer.rb
+++ b/test/test_tracer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'tmpdir'
 
diff --git a/test/test_unicode_normalize.rb b/test/test_unicode_normalize.rb
index 3dfac8b06668ae..548c8a8cee2ef8 100644
--- a/test/test_unicode_normalize.rb
+++ b/test/test_unicode_normalize.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 # Copyright Ayumu Nojima (野島 歩) and Martin J. Dürst (duerst@it.aoyama.ac.jp)
 
diff --git a/test/test_weakref.rb b/test/test_weakref.rb
index 9f671f4e22dce3..7520e6bc83dd97 100644
--- a/test/test_weakref.rb
+++ b/test/test_weakref.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'weakref'
 
diff --git a/test/test_win32api.rb b/test/test_win32api.rb
index b1856a33647af3..6e39ca3360ba68 100644
--- a/test/test_win32api.rb
+++ b/test/test_win32api.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 begin
   require "Win32API"
diff --git a/test/testunit/test4test_hideskip.rb b/test/testunit/test4test_hideskip.rb
index 7dba6f57b4844b..b870c76a84af5a 100644
--- a/test/testunit/test4test_hideskip.rb
+++ b/test/testunit/test4test_hideskip.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 $LOAD_PATH.unshift "#{File.dirname(__FILE__)}/../lib"
 
 require 'test/unit'
diff --git a/test/testunit/test4test_redefinition.rb b/test/testunit/test4test_redefinition.rb
index 77cfd450151606..894bc3d905a0de 100644
--- a/test/testunit/test4test_redefinition.rb
+++ b/test/testunit/test4test_redefinition.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 $LOAD_PATH.unshift "#{File.dirname(__FILE__)}/../lib"
 
 require 'test/unit'
diff --git a/test/testunit/test4test_sorting.rb b/test/testunit/test4test_sorting.rb
index b8bb9430b5e960..4848a78b5d4979 100644
--- a/test/testunit/test4test_sorting.rb
+++ b/test/testunit/test4test_sorting.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 $LOAD_PATH.unshift "#{File.dirname(__FILE__)}/../lib"
 
 require 'test/unit'
diff --git a/test/testunit/test_assertion.rb b/test/testunit/test_assertion.rb
index 374d6e022bdc86..4cd7bd7e4526b3 100644
--- a/test/testunit/test_assertion.rb
+++ b/test/testunit/test_assertion.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 class TestAssertion < Test::Unit::TestCase
   def test_wrong_assertion
diff --git a/test/testunit/test_hideskip.rb b/test/testunit/test_hideskip.rb
index e696b5e1dfac17..a8d7b5500ca636 100644
--- a/test/testunit/test_hideskip.rb
+++ b/test/testunit/test_hideskip.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestHideSkip < Test::Unit::TestCase
diff --git a/test/testunit/test_parallel.rb b/test/testunit/test_parallel.rb
index f068b344df5803..3d85f9c211f1a9 100644
--- a/test/testunit/test_parallel.rb
+++ b/test/testunit/test_parallel.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'timeout'
 
diff --git a/test/testunit/test_redefinition.rb b/test/testunit/test_redefinition.rb
index ed11621351474f..9129e554899088 100644
--- a/test/testunit/test_redefinition.rb
+++ b/test/testunit/test_redefinition.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestRedefinition < Test::Unit::TestCase
diff --git a/test/testunit/test_sorting.rb b/test/testunit/test_sorting.rb
index e13ca1fec6ea1c..f9de3ec1541562 100644
--- a/test/testunit/test_sorting.rb
+++ b/test/testunit/test_sorting.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestTestUnitSorting < Test::Unit::TestCase
diff --git a/test/testunit/tests_for_parallel/ptest_first.rb b/test/testunit/tests_for_parallel/ptest_first.rb
index 66c7704a45659b..f8687335b5d54e 100644
--- a/test/testunit/tests_for_parallel/ptest_first.rb
+++ b/test/testunit/tests_for_parallel/ptest_first.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestA < Test::Unit::TestCase
diff --git a/test/testunit/tests_for_parallel/ptest_forth.rb b/test/testunit/tests_for_parallel/ptest_forth.rb
index 46c88da5191a1e..8831676e1903e3 100644
--- a/test/testunit/tests_for_parallel/ptest_forth.rb
+++ b/test/testunit/tests_for_parallel/ptest_forth.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestE < Test::Unit::TestCase
diff --git a/test/testunit/tests_for_parallel/ptest_second.rb b/test/testunit/tests_for_parallel/ptest_second.rb
index 7004d6849385cd..a793c17eb33c55 100644
--- a/test/testunit/tests_for_parallel/ptest_second.rb
+++ b/test/testunit/tests_for_parallel/ptest_second.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestB < Test::Unit::TestCase
diff --git a/test/testunit/tests_for_parallel/ptest_third.rb b/test/testunit/tests_for_parallel/ptest_third.rb
index 338fc32a917e1e..3f448ecfc13c62 100644
--- a/test/testunit/tests_for_parallel/ptest_third.rb
+++ b/test/testunit/tests_for_parallel/ptest_third.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestD < Test::Unit::TestCase
diff --git a/test/testunit/tests_for_parallel/runner.rb b/test/testunit/tests_for_parallel/runner.rb
index e262e1e6c77983..bece739917a283 100644
--- a/test/testunit/tests_for_parallel/runner.rb
+++ b/test/testunit/tests_for_parallel/runner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'rbconfig'
 
 $LOAD_PATH.unshift "#{File.dirname(__FILE__)}/../../lib"
diff --git a/test/thread/test_cv.rb b/test/thread/test_cv.rb
index b399b479f46672..53c7d279b4317f 100644
--- a/test/thread/test_cv.rb
+++ b/test/thread/test_cv.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'thread'
 require 'tmpdir'
diff --git a/test/thread/test_queue.rb b/test/thread/test_queue.rb
index 0a1ae483870c22..32662babed8901 100644
--- a/test/thread/test_queue.rb
+++ b/test/thread/test_queue.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'thread'
 require 'tmpdir'
diff --git a/test/thread/test_sync.rb b/test/thread/test_sync.rb
index 9509cac6c74825..e576fc1d32308b 100644
--- a/test/thread/test_sync.rb
+++ b/test/thread/test_sync.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'sync'
 require 'timeout'
diff --git a/test/uri/test_common.rb b/test/uri/test_common.rb
index 562041535ecb06..4a7300fce710fc 100644
--- a/test/uri/test_common.rb
+++ b/test/uri/test_common.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'uri'
 
diff --git a/test/uri/test_ftp.rb b/test/uri/test_ftp.rb
index cc6843e60f293a..0eec984db8a3c1 100644
--- a/test/uri/test_ftp.rb
+++ b/test/uri/test_ftp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'uri/ftp'
 
diff --git a/test/uri/test_generic.rb b/test/uri/test_generic.rb
index 941d8ffa028d31..eda6497da27fb7 100644
--- a/test/uri/test_generic.rb
+++ b/test/uri/test_generic.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'uri'
 
diff --git a/test/uri/test_http.rb b/test/uri/test_http.rb
index 5d04e8cc6ded2e..11259886024d65 100644
--- a/test/uri/test_http.rb
+++ b/test/uri/test_http.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'uri/http'
 
diff --git a/test/uri/test_ldap.rb b/test/uri/test_ldap.rb
index a4cdbff2758f0e..adad4454b594e4 100644
--- a/test/uri/test_ldap.rb
+++ b/test/uri/test_ldap.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'uri/ldap'
 
diff --git a/test/uri/test_mailto.rb b/test/uri/test_mailto.rb
index 9001835d2853bf..4e3b0425fa6d5c 100644
--- a/test/uri/test_mailto.rb
+++ b/test/uri/test_mailto.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'uri/mailto'
 
diff --git a/test/uri/test_parser.rb b/test/uri/test_parser.rb
index 188b4f858c4b34..757ac86c746680 100644
--- a/test/uri/test_parser.rb
+++ b/test/uri/test_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'uri'
 
diff --git a/test/webrick/test_cgi.rb b/test/webrick/test_cgi.rb
index b9d066175f62f3..090286840b156c 100644
--- a/test/webrick/test_cgi.rb
+++ b/test/webrick/test_cgi.rb
@@ -1,4 +1,5 @@
 # coding: US-ASCII
+# frozen_string_literal: false
 require_relative "utils"
 require "webrick"
 require "test/unit"
diff --git a/test/webrick/test_cookie.rb b/test/webrick/test_cookie.rb
index 1652f39ee05240..ebbc5939dcc534 100644
--- a/test/webrick/test_cookie.rb
+++ b/test/webrick/test_cookie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "webrick/cookie"
 
diff --git a/test/webrick/test_do_not_reverse_lookup.rb b/test/webrick/test_do_not_reverse_lookup.rb
index 57f3b1d3efbcb5..efcb5a92990194 100644
--- a/test/webrick/test_do_not_reverse_lookup.rb
+++ b/test/webrick/test_do_not_reverse_lookup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "webrick"
 require_relative "utils"
diff --git a/test/webrick/test_filehandler.rb b/test/webrick/test_filehandler.rb
index 38b43d75fbdd31..663b237a82f649 100644
--- a/test/webrick/test_filehandler.rb
+++ b/test/webrick/test_filehandler.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require_relative "utils.rb"
 require "webrick"
diff --git a/test/webrick/test_htmlutils.rb b/test/webrick/test_htmlutils.rb
index 1fe49ee226d69d..ae1b8efa954a58 100644
--- a/test/webrick/test_htmlutils.rb
+++ b/test/webrick/test_htmlutils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "webrick/htmlutils"
 
diff --git a/test/webrick/test_httpauth.rb b/test/webrick/test_httpauth.rb
index 27c37f36770b02..4376b91842c9b6 100644
--- a/test/webrick/test_httpauth.rb
+++ b/test/webrick/test_httpauth.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "net/http"
 require "tempfile"
diff --git a/test/webrick/test_httpproxy.rb b/test/webrick/test_httpproxy.rb
index 501bb4cbe50a59..6837f0c7385730 100644
--- a/test/webrick/test_httpproxy.rb
+++ b/test/webrick/test_httpproxy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "net/http"
 require "webrick"
diff --git a/test/webrick/test_httprequest.rb b/test/webrick/test_httprequest.rb
index 3a7e67579f3a33..45d26f86999fca 100644
--- a/test/webrick/test_httprequest.rb
+++ b/test/webrick/test_httprequest.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "webrick"
 require "stringio"
 require "test/unit"
diff --git a/test/webrick/test_httpresponse.rb b/test/webrick/test_httpresponse.rb
index c916ed57c25666..b3f06cd4694a4a 100644
--- a/test/webrick/test_httpresponse.rb
+++ b/test/webrick/test_httpresponse.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "webrick"
 require "minitest/autorun"
 require "stringio"
diff --git a/test/webrick/test_httpserver.rb b/test/webrick/test_httpserver.rb
index 933aa0e02ed5fa..e718738fc17166 100644
--- a/test/webrick/test_httpserver.rb
+++ b/test/webrick/test_httpserver.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "net/http"
 require "webrick"
diff --git a/test/webrick/test_httputils.rb b/test/webrick/test_httputils.rb
index 2753cbe6c900b1..00f297bd09e626 100644
--- a/test/webrick/test_httputils.rb
+++ b/test/webrick/test_httputils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "webrick/httputils"
 
diff --git a/test/webrick/test_httpversion.rb b/test/webrick/test_httpversion.rb
index 81a871a226a5d1..e50ee179710a71 100644
--- a/test/webrick/test_httpversion.rb
+++ b/test/webrick/test_httpversion.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "webrick/httpversion"
 
diff --git a/test/webrick/test_server.rb b/test/webrick/test_server.rb
index 1a720361cc5d88..4d539d0368f3af 100644
--- a/test/webrick/test_server.rb
+++ b/test/webrick/test_server.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "tempfile"
 require "webrick"
diff --git a/test/webrick/test_utils.rb b/test/webrick/test_utils.rb
index fc68124e4411d6..23996de5d20a2f 100644
--- a/test/webrick/test_utils.rb
+++ b/test/webrick/test_utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "test/unit"
 require "webrick/utils"
 
diff --git a/test/webrick/utils.rb b/test/webrick/utils.rb
index 71559a56284363..ce667df3557f24 100644
--- a/test/webrick/utils.rb
+++ b/test/webrick/utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require "webrick"
 begin
   require "webrick/https"
diff --git a/test/win32ole/err_in_callback.rb b/test/win32ole/err_in_callback.rb
index fabb7bef0ef641..aa6c9c7e3a56e9 100644
--- a/test/win32ole/err_in_callback.rb
+++ b/test/win32ole/err_in_callback.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'win32ole'
 db = WIN32OLE.new('ADODB.Connection')
 db.connectionString = "Driver={Microsoft Text Driver (*.txt; *.csv)};DefaultDir=.;"
diff --git a/test/win32ole/test_err_in_callback.rb b/test/win32ole/test_err_in_callback.rb
index cae6d493cbef52..2c2b4a61a1728d 100644
--- a/test/win32ole/test_err_in_callback.rb
+++ b/test/win32ole/test_err_in_callback.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # test Win32OLE avoids cfp consistency error when the exception raised
 # in WIN32OLE_EVENT handler block. [ruby-dev:35450]
diff --git a/test/win32ole/test_folderitem2_invokeverb.rb b/test/win32ole/test_folderitem2_invokeverb.rb
index c5ec88c2182136..e11503ca2aae5a 100644
--- a/test/win32ole/test_folderitem2_invokeverb.rb
+++ b/test/win32ole/test_folderitem2_invokeverb.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # This script check that Win32OLE can execute InvokeVerb method of FolderItem2.
 #
diff --git a/test/win32ole/test_nil2vtempty.rb b/test/win32ole/test_nil2vtempty.rb
index 8508ecdf971614..49757d61b397c2 100644
--- a/test/win32ole/test_nil2vtempty.rb
+++ b/test/win32ole/test_nil2vtempty.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 # This is test script to check that WIN32OLE should convert nil to VT_EMPTY in second try.
 # [ruby-talk:137054]
 begin
diff --git a/test/win32ole/test_ole_methods.rb b/test/win32ole/test_ole_methods.rb
index 869828d22fcdb9..cb903566b9f544 100644
--- a/test/win32ole/test_ole_methods.rb
+++ b/test/win32ole/test_ole_methods.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # This is test for [ruby-talk:196897]
 #
diff --git a/test/win32ole/test_propertyputref.rb b/test/win32ole/test_propertyputref.rb
index 24459afe9bcf23..93edb508351c95 100644
--- a/test/win32ole/test_propertyputref.rb
+++ b/test/win32ole/test_propertyputref.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 begin
   require 'win32ole'
diff --git a/test/win32ole/test_thread.rb b/test/win32ole/test_thread.rb
index 56a63579322ace..f1cdfe32b0f2a9 100644
--- a/test/win32ole/test_thread.rb
+++ b/test/win32ole/test_thread.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole.rb b/test/win32ole/test_win32ole.rb
index 6cf2b3ce3f6aea..c095e6d7ce8916 100644
--- a/test/win32ole/test_win32ole.rb
+++ b/test/win32ole/test_win32ole.rb
@@ -1,4 +1,5 @@
 # coding: us-ascii
+# frozen_string_literal: false
 
 begin
   require 'win32ole'
diff --git a/test/win32ole/test_win32ole_event.rb b/test/win32ole/test_win32ole_event.rb
index f91f0a10c55a03..02bbeee3210265 100644
--- a/test/win32ole/test_win32ole_event.rb
+++ b/test/win32ole/test_win32ole_event.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole_method.rb b/test/win32ole/test_win32ole_method.rb
index 2a4e3d0896634d..7fb43fd5426720 100644
--- a/test/win32ole/test_win32ole_method.rb
+++ b/test/win32ole/test_win32ole_method.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole_param.rb b/test/win32ole/test_win32ole_param.rb
index 1a4eeff301075e..4f8104b1d10cea 100644
--- a/test/win32ole/test_win32ole_param.rb
+++ b/test/win32ole/test_win32ole_param.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole_record.rb b/test/win32ole/test_win32ole_record.rb
index e32a9e2a954431..654c747711c987 100644
--- a/test/win32ole/test_win32ole_record.rb
+++ b/test/win32ole/test_win32ole_record.rb
@@ -1,4 +1,5 @@
 # coding: us-ascii
+# frozen_string_literal: false
 
 begin
   require 'win32ole'
diff --git a/test/win32ole/test_win32ole_type.rb b/test/win32ole/test_win32ole_type.rb
index 5422352f044433..ce11e0235ff9da 100644
--- a/test/win32ole/test_win32ole_type.rb
+++ b/test/win32ole/test_win32ole_type.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole_typelib.rb b/test/win32ole/test_win32ole_typelib.rb
index a548bc153478b2..321c019e53ee88 100644
--- a/test/win32ole/test_win32ole_typelib.rb
+++ b/test/win32ole/test_win32ole_typelib.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole_variable.rb b/test/win32ole/test_win32ole_variable.rb
index 5fdcb07e4c3822..826029e0a8d116 100644
--- a/test/win32ole/test_win32ole_variable.rb
+++ b/test/win32ole/test_win32ole_variable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole_variant.rb b/test/win32ole/test_win32ole_variant.rb
index 27ede7d74199bf..0d27aae5ed6c3b 100644
--- a/test/win32ole/test_win32ole_variant.rb
+++ b/test/win32ole/test_win32ole_variant.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole_variant_m.rb b/test/win32ole/test_win32ole_variant_m.rb
index b3e48c20f08503..25ad56cc21f976 100644
--- a/test/win32ole/test_win32ole_variant_m.rb
+++ b/test/win32ole/test_win32ole_variant_m.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_win32ole_variant_outarg.rb b/test/win32ole/test_win32ole_variant_outarg.rb
index ffc8e067bdced7..aa5793b84cb330 100644
--- a/test/win32ole/test_win32ole_variant_outarg.rb
+++ b/test/win32ole/test_win32ole_variant_outarg.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 begin
   require 'win32ole'
 rescue LoadError
diff --git a/test/win32ole/test_word.rb b/test/win32ole/test_word.rb
index a67b80bb76661a..03b0bcbddee714 100644
--- a/test/win32ole/test_word.rb
+++ b/test/win32ole/test_word.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # This is test for [ruby-Bugs#3237]
 #
diff --git a/test/xmlrpc/test_client.rb b/test/xmlrpc/test_client.rb
index b189728bc6c37f..5a74c5265b2601 100644
--- a/test/xmlrpc/test_client.rb
+++ b/test/xmlrpc/test_client.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'xmlrpc/client'
 require 'net/http'
diff --git a/test/xmlrpc/test_cookie.rb b/test/xmlrpc/test_cookie.rb
index cfcfe4c3f0b54d..32eedca36786bb 100644
--- a/test/xmlrpc/test_cookie.rb
+++ b/test/xmlrpc/test_cookie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'time'
 require 'webrick'
diff --git a/test/xmlrpc/test_datetime.rb b/test/xmlrpc/test_datetime.rb
index d6bb95dfcc2dba..6a46e15f842ae9 100644
--- a/test/xmlrpc/test_datetime.rb
+++ b/test/xmlrpc/test_datetime.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "xmlrpc/datetime"
 
diff --git a/test/xmlrpc/test_features.rb b/test/xmlrpc/test_features.rb
index 48bb0d4c2154fe..ea97ab8a09df29 100644
--- a/test/xmlrpc/test_features.rb
+++ b/test/xmlrpc/test_features.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "xmlrpc/create"
 require "xmlrpc/parser"
diff --git a/test/xmlrpc/test_marshal.rb b/test/xmlrpc/test_marshal.rb
index 34ddfa9d82218d..251f9f6f2908cb 100644
--- a/test/xmlrpc/test_marshal.rb
+++ b/test/xmlrpc/test_marshal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require "xmlrpc/marshal"
 
diff --git a/test/xmlrpc/test_parser.rb b/test/xmlrpc/test_parser.rb
index 5591645cd458d9..880044284c011c 100644
--- a/test/xmlrpc/test_parser.rb
+++ b/test/xmlrpc/test_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'xmlrpc/datetime'
 require "xmlrpc/parser"
diff --git a/test/xmlrpc/test_webrick_server.rb b/test/xmlrpc/test_webrick_server.rb
index bc102390c36592..268a01382d5caf 100644
--- a/test/xmlrpc/test_webrick_server.rb
+++ b/test/xmlrpc/test_webrick_server.rb
@@ -1,4 +1,5 @@
 # coding: utf-8
+# frozen_string_literal: false
 
 require 'test/unit'
 require 'webrick'
diff --git a/test/xmlrpc/webrick_testing.rb b/test/xmlrpc/webrick_testing.rb
index 37c0b69a740b80..ff287f70249a16 100644
--- a/test/xmlrpc/webrick_testing.rb
+++ b/test/xmlrpc/webrick_testing.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'timeout'
 
 module TestXMLRPC
diff --git a/test/zlib/test_zlib.rb b/test/zlib/test_zlib.rb
index b22e04eb621101..37d4b69b0a2ed6 100644
--- a/test/zlib/test_zlib.rb
+++ b/test/zlib/test_zlib.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 require 'stringio'
 require 'tempfile'