re-base a class that uses super() in order to unit test it

rebase.py

from __future__ import print_function

# some library
class Base(object):
    def method(self):
        return "This is hard to stub"

# my code
class UUT(Base):
    def method(self):
        return "I want to unit test this class " + super(UUT, self).method()

print("Vanilla:", UUT().method())

# my tests
class MockBase(object):
    def method(self):
        return "stubbed!"

class Rebaser(type):
    def __new__(mcs, name, bases, dict):
        bases += (MockBase, )
        return type.__new__(mcs, name, bases, dict)
    def mro(cls):
        return (cls, UUT, MockBase) + UUT.__mro__[1:]

class TestThis2(UUT):
    __metaclass__ = Rebaser


print("Test:", TestThis2().method())


# output:
# Vanilla: I want to unit test this class This is hard to stub
# Test: I want to unit test this class stubbed!
# (<class '__main__.TestThis2'>, <class '__main__.UUT'>,
#  <class '__main__.MockBase'>, <class '__main__.Base'>,
#  <type 'object'>)