To be clear, there definitely should be unit tests run via a CI system. That's a minimum bar instead of a cure-all though. What checks that there are enough uni

To be clear, there definitely should be unit tests run via a CI system. That's a minimum bar instead of a cure-all though. What checks that there are enough unit tests to cover appropriate cases, but not so many as to be noisy or excessively time-consuming? What checks that the tests actually assert the correct behavior? Code review does. What do you do when your test suite takes multiple hours to run, but still doesn't catch all of the bugs? IMO, you can only really apply one ideological principle to your practices. I think that should be that your code works correctly while being no more complex than needed. Ideally many things shouldn't need to be done, but in the end, you do what you need to do to make sure that's true, including reviewers checking out code and working with it. If your ideological principle is instead that reviewers must never checkout code and try it, then you will eventually sacrifice the other in favor of it. I don't think that's a good result.