Review the main features of the unittest.mock module with a big dive into how to use it effectively and avoid most of the mistakes beginner and intermediate users fall into when using it. The video includes why mocks are needed, how to use them, and how they work; how to patch code to isolate it from internal dependencies; and different kinds of mocks that fit different scenarios.
Here we will build a simple todo app following roughly the same steps as in the Part I of TDD with Python book.