For the purposes of this post, unit tests, will be analogous to any automated testing system. Whether unit tests, integration tests, or any other means of having computers run reliable tests to verify that code is doing what it is intended to do. When I was first introduced to the idea of automated, unit style, testing, I got it right away. It was one of those, "of course, why didn't I think of that" moments. It seemed like such an obvious improvement to me that it has been hard for me to understand why everyone isn't doing it, and doing it all the time. Since I have learned about unit testing, I have focused my learning and growth toward understanding how and where to use unit tests and how to make my code work better with unit tests. In that time I have improved my code and myself as a developer. I have also heard some arguments as to why everyone isn't always developing software with unit tests. For a large application that has been developed over many year...