How do you expect AI to write unit tests if it doesn't know the precise desired semantics (specification)? What I personally would like AI to do would be to re

How do you expect AI to write unit tests if it doesn't know the precise desired semantics (specification)? What I personally would like AI to do would be to refactor the program so it would be shorter/clearer, without changing its semantics. Then, I (human) could easily review what it does, whether it conforms to the specification. (For example, rewrite the C program to give exactly the same output, but as a Python code.) In cases where there is a peculiar difference between the desired semantics and real semantics, this would become apparent as additional complexity in the refactored program. For example, there might be a subtle semantic differences between C and Python library functions. If the refactored program would use a custom reimplementation of C function instead of the Python function, it would indicate that the difference matters for the program semantics, and needs to be somehow further specified, or it can be a bug in one of the implementations.