How to mock chained methods on Django models

Question

I am trying to do something like this to mock methods on a Django model using the Python mock library:

# file: tasks.py
def delete_ads(user):    
    # works fine and return a list of 4 MagicMock objects
    ads = Classifieds.objects.filter(
        user=user
    )

# file: tests.py
def test_delete_ads():
    return_list = [MagicMock(name='1'), MagicMock(name='2'), MagicMock(name='3'), MagicMock(name='4')]

    with patch('user.tasks.Classifieds') as classified_mock:
        classified_mock.objects.filter.return_value = return_value

The above code works fine but starts returning a single MagicMock object after I change my code to this:

# file: tasks.py
def delete_ads(user):    
    # works fine and return a list of 4 MagicMock objects
    ads = Classifieds.objects.filter(
        user=user
    ).order_by('-added')

# file: tests.py
def test_delete_ads():
    return_list = [MagicMock(name='1'), MagicMock(name='2'), MagicMock(name='3'), MagicMock(name='4')]

    with patch('user.tasks.Classifieds') as classified_mock:
        classified_mock.objects.filter.order_by.return_value = return_value

Is there anyway that I can do this correctly even when I am chaining method calls on Django models?

You have a number of typos in your question. Are you sure these are not also in your code? — Dunes, Jul 13 '14 at 10:39
@Dunes Yep I am pretty sure typos are not in my code. I typed this separately. — Rafay, Jul 13 '14 at 11:03

score 1 · Answer 1 · answered Jul 13 '14 at 10:47

When mocking the return value of a mocked function you must mock the function as it would be called in the code. parent.child creates an attribute called child on the parent mock. Whereas, parent().child creates an attribute called child on the mocked return value of parent().

How to mock chained methods on Django models

1 Answers1