test/spec layers an RSpec-inspired interface on top of Test::Unit, so you can mix TDD and BDD (Behavior-Driven Development). test/spec is a clean-room implementation that maps most kinds of Test::Unit assertions to a 'should'-like syntax. This is a fork of the main version to add some features and make things a bit easier for developers. It grew out of day to day use at Relevance (http://thinkrelevance.com).