What is your favorite Python mocking library? [closed]

What is your single favorite mocking library for Python?

I've only used one, but I've had good results with Michael Foord's Mock: http://www.voidspace.org.uk/python/mock/.

Michael's introduction says it better than I could:

There are already several Python mocking libraries available, so why another one?

Most mocking libraries follow the 'record -> replay' pattern of mocking. I prefer the 'action -> assertion' pattern, which is more readable and intuitive particularly when working with the Python unittest module.

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It also provides utility functions / objects to assist with testing, particularly monkey patching.

Mox, from Google

Mocker from Gustavo Niemeyer.

It's not perfect, but it is very powerful and flexible.