[core] Handle RSpec description with japanese char in CP932 encoded f…

…iles

When the user create a test with CP932 encoding and japanese chars RSpec
fail to properly display characters or crash with the error:

>  Encoding::CompatibilityError: incompatible character encodings: Windows-31J and UTF-8

Fix:
- rspec/rspec-core#2570
- https://github.com/rspec/rspec-core/issues/2543

For Ruby 1.8.7
We are following the same behavior as for rspec-support
https://github.com/rspec/rspec-support/blob/9940a8656071655b807f772f36101b4d27f1b67d/lib/rspec/support/spec/string_matcher.rb#L8

---
This commit was imported from rspec/rspec-core@05611c5.

rspec-core/lib/rspec/core/formatters/exception_presenter.rb

@@ -81,7 +81,7 @@ def fully_formatted(failure_number, colorizer=::RSpec::Core::Formatters::Console
 
         def fully_formatted_lines(failure_number, colorizer)
           lines = [
-            description,
+            encoded_description(description),
             detail_formatter.call(example, colorizer),
             formatted_message_and_backtrace(colorizer),
             extra_detail_formatter.call(failure_number, colorizer),
@@ -244,6 +244,16 @@ def formatted_message_and_backtrace(colorizer)
           end
         end
 
+        def encoded_description(description)
+          return if description.nil?
+
+          if String.method_defined?(:encoding)
+            encoded_string(description)
+          else # for 1.8.7
+            description
+          end
+        end
+
         def exception_backtrace
           exception.backtrace || []
         end

rspec-core/spec/rspec/core/formatters/exception_presenter_spec.rb

@@ -94,6 +94,23 @@ module RSpec::Core
         EOS
       end
 
+      if String.method_defined?(:encoding)
+        it 'allows the caller to add encoded description' do
+          the_presenter = Formatters::ExceptionPresenter.new(exception, example,
+                                                             :description => "ジ".encode("CP932"))
+
+          expect(the_presenter.fully_formatted(1)).to eq(<<-EOS.gsub(/^ +\|/, ''))
+          |
+          |  1) ジ
+          |     Failure/Error: # The failure happened here!#{ encoding_check }
+          |
+          |       Boom
+          |       Bam
+          |     # ./spec/rspec/core/formatters/exception_presenter_spec.rb:#{line_num}
+          EOS
+        end
+      end
+
       it 'allows the caller to omit the description' do
         the_presenter = Formatters::ExceptionPresenter.new(exception, example,
                                                        :detail_formatter => Proc.new { "Detail!" },