Doublex is a test doubles framework for the Python unittest module. It may be used as a effective tool to perform Test Driven Development.

It provides stubs, spies, proxy-spies, mocks, individual methods, properties, etc. Methods support observer attachment or delegate return value generation to iterables, generators or even third party functions. A special double factory (called Mimic) allows one to create doubles inheriting original class superclasses. This provides replacements for the original instances even for code performing explicit type checking.

doublex supersedes pyDoubles and it provides its legacy API as a wrapper.