Add spec to track Ripper support for each Ruby implementation

Author: yujinakayama

spec/rspec/support/ruby_features_spec.rb

@@ -99,7 +99,7 @@ module Support
             ::Ripper.lex('foo')
           end
 
-          if !defined?(RUBY_ENGINE) || RUBY_ENGINE == 'ruby'
+          if Ruby.mri?
             context 'on MRI' do
               context '1.8.x', :if => RUBY_VERSION.start_with?('1.8.') do
                 it 'is not supported' do
@@ -115,11 +115,19 @@ module Support
             end
           end
 
-          if defined?(JRUBY_VERSION)
+          if Ruby.jruby?
             context 'on JRuby' do
               context '1.7.x', :if => JRUBY_VERSION.start_with?('1.7.') do
-                it 'is supported' do
-                  expect(line_number).to eq(1)
+                context 'in 1.8 mode', :if => RUBY_VERSION.start_with?('1.8.') do
+                  it 'is not supported' do
+                    expect { tokens }.to raise_error(LoadError)
+                  end
+                end
+
+                context 'in non 1.8 mode', :unless => RUBY_VERSION.start_with?('1.8.') do
+                  it 'is supported' do
+                    expect(line_number).to eq(1)
+                  end
                 end
               end