Use simple testing via ENV variable matrix

Appraisal is nice but it can be simplified.
Additionally, it doesn't currently support the bundler plugin api so
override_gem, plugin, etc., won't work.  We do this in some repositories
so unless there's a reason to stick with appraisal, it's safer
to use a solution that's simpler and more future-proof.

See: `https://github.com/thoughtbot/appraisal/issues/178`

.gitignore

@@ -1,7 +1,6 @@
 /.bundle/
 /.yardoc
 /Gemfile.lock
-/gemfiles/*gemfile.lock
 /_yardoc/
 /coverage/
 /doc/

.travis.yml

@@ -5,9 +5,10 @@ rvm:
 - 2.7.5
 - 3.0.3
 cache: bundler
-gemfile:
-  - gemfiles/rails_6.0.gemfile
-  - gemfiles/rails_6.1.gemfile
+env:
+  matrix:
+    - TEST_RAILS_VERSION=6.1
+    - TEST_RAILS_VERSION=6.0
 addons:
   postgresql: '10'
 before_script:

Gemfile

@@ -2,3 +2,12 @@ source 'https://rubygems.org'
 
 # Specify your gem's dependencies in activerecord-id_regions.gemspec
 gemspec
+
+case ENV['TEST_RAILS_VERSION']
+when "6.0"
+  gem "activerecord",  "~>6.0.4"
+  gem "activesupport", "~>6.0.4"
+when "6.1"
+  gem "activerecord",  "~>6.1.4"
+  gem "activesupport", "~>6.1.4"
+end

activerecord-id_regions.gemspec

@@ -24,7 +24,6 @@ Gem::Specification.new do |spec|
   spec.add_dependency "activesupport", ">= 5.0", "< 7.0"
   spec.add_dependency "pg"
 
-  spec.add_development_dependency "appraisal"
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "manageiq-style"
   spec.add_development_dependency "rake"

spec/spec_helper.rb

@@ -76,3 +76,9 @@ def change
     create_table :test_records, :id => :bigserial
   end
 end
+
+require "active_record"
+require "active_support"
+puts
+puts "\e[93mUsing ActiveRecord #{ActiveRecord.version}\e[0m"
+puts "\e[93mUsing ActiveSupport #{ActiveSupport.version}\e[0m"