pytest-mock for enhanced mocking - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is pytest-mock and why is it useful?

pytest-mock is a plugin for pytest that simplifies mocking in tests by providing a mocker fixture. It helps replace parts of your system under test with mock objects easily and cleanly.

beginner

How do you use the mocker fixture in a pytest test function?

You add mocker as a parameter to your test function. Then use mocker.patch() to replace a function or object with a mock during the test.

intermediate

What is the difference between mocker.patch and unittest.mock.patch?

mocker.patch is a pytest-mock wrapper around unittest.mock.patch. It integrates better with pytest, automatically cleans up mocks after tests, and provides simpler syntax.

intermediate

How does pytest-mock help with test cleanup?

pytest-mock automatically undoes all patches after each test, so you don't need to manually stop or reset mocks. This prevents side effects between tests.

beginner

Give an example of mocking a function using pytest-mock.

Example: ```python def test_example(mocker): mock_func = mocker.patch('module.function_to_mock') mock_func.return_value = 42 result = module.function_to_mock() assert result == 42 ```

What is the main benefit of using pytest-mock over unittest.mock directly?

A Requires no imports

B Automatic cleanup of mocks after each test

C Supports only Python 2

D Faster test execution

pytest-mock automatically undoes patches after each test, preventing side effects and making tests cleaner.

How do you apply a mock patch using pytest-mock?

A Use mocker.mock('target')

B Call unittest.mock.patch directly without parameters

C Use mocker.patch('target') inside a test function with mocker parameter

D Add @patch decorator to the test function

pytest-mock provides the mocker fixture, and you use mocker.patch('target') inside your test function.

What does mocker.patch return?

A A mock object replacing the target

B The original function

C A boolean indicating success

D None

mocker.patch returns a mock object that replaces the target during the test.

Which of these is true about pytest-mock's mocker fixture?

A It is automatically available when pytest-mock is installed

B It must be imported manually in each test file

C It only works with unittest tests

D It disables all mocks after the test

When pytest-mock is installed, the mocker fixture is automatically available in pytest tests.

If you want to mock a method 'foo' in class 'Bar' in module 'baz', what is the correct patch target string?

A 'baz.foo.Bar'

B 'Bar.foo'

C 'foo.Bar.baz'

D 'baz.Bar.foo'

The patch target string uses the full import path: 'baz.Bar.foo'.

Explain how pytest-mock simplifies mocking in pytest tests.

Think about how mocker.patch works and test cleanup.

Describe the steps to mock a function using pytest-mock and verify its return value.

Consider a simple example mocking a function to return a fixed value.