When developers first discover the wonders of test-driven development, it’s like gaining entrance to a new and better world with less stress and insecurity. It truly is a wonderful experience well worth celebrating. But internalizing the benefits of testing is only the first step to enlightenment. Knowing what not to test is the harder part of the lesson. While as a beginner you shouldn’t worry much about what not to test on day one, you better start picking it up by day two. Humans are creatures of habit, and if you start forming bad habits of over-testing early on, it will be h...