Learning your test framework should not be the hard part of testing.
Quickly get up to speed with unittest, nose, and pytest.
This book starts with unittest, the xUnit style testing framework that is included as a standard library in Python. I walk through writing tests and running them, including a comprehensive look at unittest fixtures (setup and teardown at multiple levels).
I move on and cover Nose with the same examples as used in unittest, making it easy to compare/contrast the two frameworks.
Nose can run unittest, but you can also have non-unittest test classes, as well as stand alone test functions. The fixture model is also extended. All of this is covered in the book.
The last section is pytest. Pytest has all of the functionality of unittest, and nose, and then so much more. The fixture model for pytest can be daunting at first if you don't have a guide. That's why I start simple and walk you through from simple fixtures to more complex use cases.
Although I don't cover all of pytest capabilities, there's enough in here to get you to the advanced-intermediate pytest user gently but quickly.
You get this in pdf, epub, and mobi.