Stop Guessing - Automated Unit Tests Tell You How Your Code Behaves

Automated Unit Tests, or AUT, are a concept that most developers do not initially see as beneficial. When I was introduced to AUT, my reaction was was, “I’m going to write buggy code, to test my buggy code.” It takes takes time to see the true benefit of AUT. As time has gone on, I've become a huge proponent for AUT. The true purpose of AUT is to allow the developer to be sure the code behaves as expected. Burn that bold text into your head because it will be the theme of everything here. On the surface, it sounds like I just said the same thing about buggy code testing buggy code. But that is not really what is happening. I am able to test what happens inside my code. I am able to go through different scenarios in milliseconds. I am able to verify success cases, failure cases, edge cases, and exception paths without waiting on a database, a file system, another service, or human interaction. That is where the value starts to show up. A few years ago, a friend reached out to me saying