Unit tests are essential. I've developed some devops code around self-healing where the degrading signals were not reproducible. We knew they occurred because w

Unit tests are essential. I've developed some devops code around self-healing where the degrading signals were not reproducible. We knew they occurred because we lost a non-trivial number of nodes a day. A weird set of bugs between Linux, Kubernetes & Docker. The problem was we could recognize the signals and take action. The entire daemon I created to trap and execute on these was built and deployed on unit tests. In fact, I had more lines of unit test code than actual functional code because I had to mock the hell out of what the actual system would look like. Another situation - where my wife used to work in medical devices. Feature development velocity was a problem because there was a queue on the very limited set of devices (CT scanners, PET scanners, etc.) that the team could use for testing. Debugging was very hard. Fixing bugs was hard because to debug you needed a device. With unit testing and mocks they made a lot of contention on the devices go away. Write your unit tests. It will help you and the people coming in after you to maintain the code.