A new yak for the herd: BeeKeeper
Testing is a skill that is a vital part of every programmer's training. Learning how to write good tests helps you write more robust code, and ensures that when you've written code that works, it keeps working long into the future. It can also help you write better code in the first place. It turns out that well architected code, with high cohesion and low coupling, is also easy to test - so writing code that is easy to test will almost always result in better overall code quality.