What are the best practices for mocking in Python?

What are the best practices for mocking in Python?

When mocking in Python, it's important to use the unittest.mock library. Key practices include using patch to replace dependencies, ensuring your mocks are as specific as possible, and avoiding over-mocking.

Can you give an example of using patch?

Sure! Here's a simple example:

from unittest.mock import patch

def get_data():
    # Imagine this function fetches data from an API
    pass

@patch('module_containing_get_data.get_data')
def test_function(mock_get_data):
    mock_get_data.return_value = 'mocked data'
    assert get_data() == 'mocked data'

What should I avoid when mocking?

Avoid mocking built-in functions or methods unless absolutely necessary, as it can lead to confusing tests. Also, don't mock too much; it can make your tests brittle.

How do I know if I'm over-mocking?

If your tests are failing due to changes in the implementation rather than the behavior, or if they become hard to read, you might be over-mocking.