I like to think of tests and the team's emotional relationship to them as a barometer of the extent to which the repo is and has consistently followed best prac

I like to think of tests and the team's emotional relationship to them as a barometer of the extent to which the repo is and has consistently followed best practices in the language. IOW, enforcing unit and functional testing forces developers to follow best practices. If I find myself dreading writing and maintaining tests, it's a great indicator that the code diverged from best practices at some point in the past, and that the technical debt has just been accumulating ever since. Difficult to test code is code smell telling me that the technical debt is getting out of control or that the code is getting unmaintainable, and this can be difficult to walk back. Another great indicator is the extent to which the team "detests" mocking. Mocking is great -- when it's trivial to do. When it's not trivial, and elaborate mocking behavior and reflection and testing of private methods, etc. is needed, it's another indicator that best practices have been sacrificed for expediency.