如何重新定义python3 MagicMock魔术方法？

Question

I need to redefine MagicMock's magic method in the child class and then use child class for testing, so I've tried:

from unittest.mock import MagicMock


class MockForTest(MagicMock):
    def __lt__(self):
        return self


t1 = MockForTest()
print(t1.__lt__())  # prints NotImplemented

But why NotImplemented ? I know I can do it:

class A():
    def __lt__(self):
        return NotImplemented


class B(A):
    def __lt__(self):
        return self


b = B()
print(b.__lt__())  # prints <__main__.B object at 0x000001D6EE77B2B0>

So, I can't redefine MagicMock 's magic methods?

Answer 1

You can use instead

t1.__lt__.return_value = t1

From what I can understand from https://github.com/python/cpython/blob/4002d5dbf4c058bbf2462f9f5dea057956d1caff/Lib/unittest/mock.py#L1834 MagicMixin remove all other magic methods.