I just pushed the gem for version 0.9 of Atto, a self-contained, ultra tiny testing framework inspired by and partially based on Nanotest by mynyml. Atto has atto, an automatic test runner, and has support for ANSI colors built in. I’m using it extensively for several of my own projects, and I think it’s nice because it keeps the unit tests simple and quick to write. Ideal for people who like a minimalistic approach to testing.