No matter whether one is using black-box, white-box, or both types of testing, the order in which they are written is very important.
Requirements (specifications and user stories) are written before the code that implements them. They come first so they define the code, not the other way around. The same can be said for tests. If they are written after the code is done, in a certain way, that code (and the functionalities it implements) is defining tests. Tests that are defined by an already existing application are biased. They have a tendency to confirm what code does, and not to test whether a client's expectations are met, or that the code is behaving as expected. With manual testing, that is less the case since it is often ...
