Tampering class method in python (temporarily replacing/mocking/faking for unit test)

tamper.py

import functools


def tamper(target, attr_name, mock_obj):
    def decor(func):
        @functools.wraps(func)
        def worker(*args, **kwargs):
            backup = getattr(target, attr_name)
            try:
                setattr(target, attr_name, mock_obj)
                func(*args, **kwargs)
            finally:
                setattr(target, attr_name, backup)

        return worker

    return decor


def tamper_class_method(method, mock_obj):
    """Temporarily replace class method with another object

    >>> class A:
    ...     def foo(self):
    ...         print 'foo', self
    ...
    >>> A().foo()
    foo
    >>> def goo(self): print 'goo', self
    ...
    >>> @tamper(A.foo, goo)
    ... def test():
    ...     A().foo()
    ...
    >>> test()
    goo
    """
    target = method.im_class
    attr_name = method.im_func.__name__
    return tamper(target, attr_name, mock_obj)