Minitest, despite its size and simplicity, is an oft-misunderstood toolset. Sandi Metz and cohort have given fantastic talks on the process of testing and what to test. This talk will focus on the testing tools themselves. Not just how to use them, but how they’re made, how they work, and what we’ve done to make them cleaner, easier to use, and easier to extend to your needs. I’ll talk about my minitest, Mike Moore’s minitest-rails, and Aaron Patterson’s minitest integration changes to rails itself.