获取在单元测试期间调用方法的值

Question

I am using pytest_mock to mock a function call. I would like to inspect the call to doB() to see if it was called with the value 3. How would I write the assert for this?

def testtest(mocker):
    # arrange
    mocker.patch.object(ClassA, 'doB', return_value=None)
    sut = ClassA()
    # act
    actual = sut.party(4) # will make a call to doB
    expected = 3
    # assert

Answer 1

Maybe something like this:

def testtest(mocker):
    # arrange
    mocked_doB = mocker.patch.object(ClassA, 'doB', return_value=None)
    sut = ClassA()
    # act
    actual = sut.party(4) # will make a call to doB
    expected = 3
    # assert
    mocked_doB.assert_called_once_with(expected)

If you assign a value to the mocked object, in this case variable mocked_doB , you will get a MagicMock object back. With this MagicMock object, you have access to all kind of methods from the unittest.mock Mock class, eg

• assert_called_once_with()
• call_count,
• and many more...

See here: https://docs.python.org/3/library/unittest.mock.html#the-mock-class

This works because with the pytest-mock framework you can directly access the mock module from mocker . This is stated here under "Usage", https://pypi.org/project/pytest-mock/ .