start rewriting for parfait #25

just some infrastructure for now.

test/ruby/helper.rb

@@ -13,5 +13,11 @@ module Ruby
       FIXMERubyXCompiler.new(input).ruby_to_vool
     end
 
+    def assert_raises_muted &block
+      orig_stdout = $stdout
+      $stdout = StringIO.new
+      assert_raises &block
+      $stdout = orig_stdout
+    end
   end
 end