bfts
Big "formal" test suite
BFTS is a branch of rubicon with the intent of auditing all of rubicon against the latest version of 1.8.x, stripping all the cruft, and getting everything up to date again. rubicon is dead and the authors have shown no interest in getting things moving again. BFTS hoped to fix that.
Later… BFTS moved into the jruby (HUGE) test compendium and some of BFTS leaked into rubyspec.
The project is now dead as there are better alternatives out there.
Get The Code
If you just want to use bfts, you can install it via RubyGems:gem install bfts
If you want to hack on bfts, clone it from GitHub:
git clone git://github.com/seattlerb/bfts