Yep. People fundamentally misunderstand how to use mocks and stubs, and often end up writing tests that test little more than “the function was written the way

Yep. People fundamentally misunderstand how to use mocks and stubs, and often end up writing tests that test little more than “the function was written the way it was currently written”. This is the worst of all possible worlds, because a test suite should accomplish two goals: identify bugs and enable refactoring. Tests like these fundamentally can’t identify bugs because they don’t test any behavior. And worse, they prohibit refactoring because any meaningful code change will alter what functions are called and in what order they’re called. So any refactor breaks almost every test, and it’s impossible to quickly tell if something “real” was broken or if it’s just an artifact of poor testing.