The most painfully obvious reason to keep a development journal came to me at work today. One of the major reasons to keep a lab journal is to log the experiments you run. This is so future you and others can read about how you did things and what results there were so that standards can be upheld and test can be rerun if needed. When I wrote my last post—and this has been baffling me all day—it did not occur to me that experiments = tests. When you are testing code write down what you did and what the results were. If you do that you won’t have to worry as much about forgetting what you tested, forgetting the results of your tests, convincing a coworker that you tested something, and convincing a coworker of the results of your tests. Future you will thank you.