Tests that “calcify the designer’s whims” - great way to put it - can be quite useful if your job description happens to be “carrying out the whims of the designer” (and for many of us, it is!)

With high coverage and dry-ish tests, changing the tests first and seeing which files start failing can function as a substitute for find+replace - by altering the tests to reflect the whims, it’ll tell you all the places you need to change your code to express said whims.