You can set the Mock.side_effect to be the original method. from unittest.mock import MagicMock class A(): def tmp(self): print(“hi”) def b(a): a.tmp() a = A() a.tmp = MagicMock(side_effect=a.tmp) b(a) a.tmp.assert_called() When side_effect is a function (or a bound method in this case, which is a kind of function), calling the Mock will also call the … Read more
First it is very important to understand that you always need to Mock where it the thing you are trying to mock out is used as stated in the unittest.mock documentation. The basic principle is that you patch where an object is looked up, which is not necessarily the same place as where it is … Read more
When you @mock.patch(‘a.A’), you are replacing the class A in the code under test with mock_a. In B.method_b you then set a = A(), which is now a = mock_a() – i.e. a is the return_value of mock_a. As you haven’t specified this value, it’s a regular MagicMock; this isn’t configured either, so you get … Read more