Assert mock arguments if arguments include another mock

Question

I have a function, for example:

def my_function1(my_obj, my_arg):
    # do something
    return

In my unittest, I want to test that a second function calls this function with the specified arguments:

def my_function2():
    obj1 = SomeClassObject()
    for arg in ["a", "b", "c"]:
        my_function1(obj1, arg)

For the test, I have mocked the object, SomeClassObject . And I also mock my_function1 so I can monitor how it is called. So my unittest looks like this:

import unittest
from unittest.mock import patch, call

class MyTest(unittest.TestCase):

    @patch("__main__.SomeClassObject", autospec=True)
    @patch("__main__.my_function1")
    def test_my_function2_calls_my_function1(self, mock_function1, mock_class_object):
        my_function2()
        calls = [call(mock_class_object, "a"),
                 call(mock_class_object, "b"),
                 call(mock_class_object, "c")]
        mock_function1.assert_has_calls(calls)

But this gives the following error three times:

AssertionError: (TypeError("missing a required argument: 'my_arg'")

I stepped through using the interactive debugger and I found that the mock_function1._mock_call_args_list is

[call(<MagicMock name='SomeClassObject' id='140060802853296'>, 'a'),
 call(<MagicMock name='SomeClassObject' id='140060802853296'>, 'b'),
 call(<MagicMock name='SomeClassObject' id='140060802853296'>, 'c')]

This is identical to what I get when I print call(mock_class_object, "a") etc. The id is exactly the same. So it looks like when I run .assert_has_calls the MagicMock object messes things up.

Does anyone know how I can do this correctly?

Answer 1

I'm not sure why exactly you get that error message, but you test for the class instead of the object as the argument. This is what should work:

class MyTest(unittest.TestCase):
    @patch("__main__.SomeClassObject", autospec=True)
    @patch("__main__.my_function1")
    def test_my_function2_calls_my_function1(self, mock_function1, mock_class):
        my_function2()
        mock_class_object = mock_class.return_value
        calls = [call(mock_class_object, "a"),
                 call(mock_class_object, "b"),
                 call(mock_class_object, "c")]
        mock_function1.assert_has_calls(calls)