It is one of those fuzzy, learn from experience type of concepts.
In my experience, taking shortcuts in tests breeds more and more shortcuts (as less experienced developers look to existing tests as reference). As the shortcuts accumulate, the tests become more brittle, less effective and harder to maintain. This is the path to having a test suite that you no longer trust.
In my experience, taking shortcuts in tests breeds more and more shortcuts (as less experienced developers look to existing tests as reference). As the shortcuts accumulate, the tests become more brittle, less effective and harder to maintain. This is the path to having a test suite that you no longer trust.
Red -> Green -> Refactor -> Refactor tests