A Python Mocking and Patching Library for Testing

mock is a Python module that provides a core Mock class. It is intended to
reduce the need for creating a host of trivial stubs throughout your test suite.
After performing an action, you can make assertions about which methods /
attributes were used and arguments they were called with. You can also specify
return values and set needed attributes in the normal way.

WWW: https://pypi.org/project/mock/