Generally refactoring is where I find tests to be super valuable. If it’s a pure refactor then the existing tests shouldn’t break. If they start failing, then y

Generally refactoring is where I find tests to be super valuable. If it’s a pure refactor then the existing tests shouldn’t break. If they start failing, then you have done something that has changed the expected behavior. For business logic I would change the tests first so that it represents the new expected result. Then you refactor the code until the tests pass.