What are the best practices for mocking in pytest?

What are the best practices for mocking in pytest?

When mocking in pytest, it's important to use the unittest.mock library effectively. Key practices include using fixtures for setup, ensuring mocks are reset between tests, and avoiding over-mocking to keep tests meaningful.

Can you give an example of using a fixture for mocking?

Sure! You can create a fixture that returns a mock object. For example:

import pytest
from unittest.mock import Mock

@pytest.fixture
def mock_service():
    return Mock()

def test_service_call(mock_service):
    mock_service.some_method.return_value = 'mocked!'
    assert mock_service.some_method() == 'mocked!'

What should I avoid when mocking?

Avoid mocking too many components at once, as it can lead to fragile tests. Also, don't mock built-in functions or libraries unless absolutely necessary, as it can obscure the behavior you're trying to test.

How can I ensure my tests are still valid with mocks?

To ensure your tests remain valid, focus on testing the behavior of your code rather than the implementation details. Use mocks to isolate the unit under test, but verify that the interactions with the mocks are correct.