PyFawkes is a mutation testing tool. It supports py.test tests in Python 3.8+.
From article at Wikipedia:
Mutation testing evaluates the quality of software tests. Mutation testing involves modifying a program's source code or byte code in small ways. A test suite that does not detect and reject the mutated code is considered defective.
PyFawkes is available on PyPI, so it can be installed via:
$ pip install pyfawkes --user --upgrade
Run PyFawkes specifying the location of your code and its unit tests:
$ python -m pyfawkes --source <PATH TO SOURCE> --test <PATH TO UNIT TESTS>