refactor: extracts parse_key

- do not remove braces
- fixes test helper

lib/bibtex/lexer.rb

@@ -302,23 +302,26 @@ def enter_object
         @mode = @active_object = :entry
         push [:NAME, @scanner.matched]
 
-        # TODO: DRY - try to parse key
         if @scanner.scan(Lexer.patterns[:lbrace])
           @brace_level += 1
           push([:LBRACE, '{'])
           @mode = :content if @brace_level > 1 || @brace_level == 1 && active?(:comment)
 
-          if @scanner.scan(Lexer.patterns[allow_missing_keys? ? :optional_key : :key])
-            key = @scanner.matched.chop.strip.tr('{}', '')
-            push [:KEY, key]
-          end
+          parse_key
         end
 
       else
         error_unexpected_object
       end
     end
 
+    def parse_key
+      return unless @scanner.scan(Lexer.patterns[allow_missing_keys? ? :optional_key : :key])
+
+      key = @scanner.matched.chop.strip
+      push [:KEY, key]
+    end
+
     # Called when parser leaves a BibTeX object.
     def leave_object
       @mode = :meta

test/helper.rb

@@ -5,7 +5,7 @@
 end
 
 begin
-  if RUBY_PLATFORM < 'java'
+  if RUBY_PLATFORM == 'java'
     require 'debug'
     Debugger.start
   else