What is the difference between a mock and a stub in unit testing?

What is the difference between a mock and a stub in unit testing?

In unit testing, a stub is a simple implementation that returns predefined responses, while a mock is a more complex object that verifies interactions.

Can you give me an example of when to use a mock instead of a stub?

Sure! Use a mock when you need to verify that a method was called with specific parameters, like in testing a service that sends notifications.

Are there any libraries you recommend for mocking and stubbing in Python?

Yes! The unittest.mock library is built into Python and is great for creating mocks and stubs. You can also use pytest-mock for more features.

What are some common mistakes to avoid when using mocks and stubs?

Common mistakes include overusing mocks, which can lead to fragile tests, and not resetting mocks between tests, which can cause false positives.