Test-driven development is one of the best benefits that Ruby on Rails brings to modern web development, but it can be a bit tricky, and laborious, constantly tweaking test code, running the tests, then making required changes. Enter autotest, part of a suite called ZenTest, which makes life dramatically easier for you. Instead of having to manually run your tests, autotest runs all of the tests in the background so you immediately see the results of your changes and whether you need to fix something. Good stuff!