Ruby

• test/testunit/test_parallel.rb, test/testunit/parallel/*:
  Test for r30939.
• lib/test/unit.rb: For test.
• lib/test/parallel.rb: For test.
• lib/test/unit/testcase.rb: For test.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@30947 b2dd03c8-39d4-4d8f-98ff-823fe69b080e