Mock something only if condition applies.

mocking_condition.py

# coding: utf-8

import functools


def _mock_condition(condition, *args, **kwargs):
    return condition(*args, **kwargs)


def mock_condition(condition):
    """
    mock something only if condition applies.

    Mocking os.remove only if file_path is /tmp/mocked.png::
        
        import os
        from unittest import mock

        def condition(*args, **kwargs):
            if '/tmp/mocked.png' in args:
                return mock.MagicMock()  # return a mock object
            return os.remove  # return original function

        mock_with_condition = mock_condition(condition)
        mock.patch('os.remove', new=mock_with_condition)
    """
    return functools.partial(condition, _mock_condition)