python3-doublex binary package in Ubuntu Xenial i386

 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.

Source package