That's basically the equivalent of RubySpec — reverse engineered from MRI (the original Ruby implementation) for use by Rubinius. It was adopted by the other al

That's basically the equivalent of RubySpec — reverse engineered from MRI (the original Ruby implementation) for use by Rubinius. It was adopted by the other alternative Ruby implementations too. It looks like the original is now gone, but a fork has taken over. Looking at some comments, fighting to get MRI to adopt it may have burnt out the people behind it.