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pytest-mock

testing

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pytest-mock is a plugin for the pytest testing framework that provides a mocker fixture, offering a convenient wrapper around the standard unittest.mock module. This integration simplifies the process of mocking objects in tests, enabling developers to replace parts of their system under test and make assertions about how they were used. The mocker fixture ensures that patches are automatically undone at the end of each test, promoting cleaner and more maintainable test code.

Usage Example​

Here’s an example of using pytest-mock to mock a function:

# content of test_example.py

import os

def remove_file(filename):
    os.remove(filename)

def test_remove_file(mocker):
    mock_remove = mocker.patch('os.remove')
    remove_file('somefile.txt')
    mock_remove.assert_called_once_with('somefile.txt')

In this example, the os.remove function is mocked using mocker.patch, allowing the test to verify that it was called with the correct argument without actually deleting any files.