I have changed if user in coordinators.user_set.all(): to if coordinators and user in coordinators.user_set.all(): in PartnerCoordiantorOnly
return user.is_superuser or (coordinators and user in coordinators.user_set.all()) in CoordinatorsOnly
if coordinators and user in coordinators.user_set.all(): it was already there in CoordinatorOrSelf, so no change.

For the test case, I went through users/test.py but found it intimidating. I have no experience with test cases :\ Please guide me how I can complete this task.

For the test case, I went through users/test.py but found it intimidating. I have no experience with test cases :\ Please guide me how I can complete this task.

Quite understandable!

We want to test the users profile view, so we'll add a test to the ViewsTestCase test case; it can be called test_user_view_no_coordinators.

The setUp function generates a bunch of users for use across this test case's tests, so if we add a new test it will already have 4 users in the database. editor4 is created as a coordinator, but we don't want any coordinators for this new test, so the first thing we should do in our new test is remove that editor from the coordinator user set:

get_coordinators().user_set.remove(self.user_coordinator)

Next, we can copy the content of test_editor_can_see_own_page - ultimately we want to do the same thing this test does, just without a coordinator existing in the database. This test first generates a request for the user profile page, as if being viewed by user_editor. It then looks at the response for that request and checks that it has a status code of 200, i.e. we successfully loaded the page. Without your code changes, this new test should fail. With it, it should pass!

I created

def test_user_view_no_coordinators(self):
        """Check that users with no coordinators can see their own pages."""
        get_coordinators().user_set.remove(self.user_coordinator)
        factory = RequestFactory()
        request = factory.get(self.url1)
        request.user = self.user_editor

        response = views.EditorDetailView.as_view()(request, pk=self.editor1.pk)
        self.assertEqual(response.status_code, 200)

But when I am trying to run this test case without any changes in view_mixins.py, it should fail but it passed.

Very curious! That suggests to me that we didn't understand the problem correctly. I actually can't reproduce it locally. I wonder if we inadvertently fixed this somewhere else.

Oh, looks like this might have been fixed in https://github.com/WikipediaLibrary/TWLight/commit/bbed99a8014f0900c92fc8e14256b9292f5481a0

Could you push just the test? It's still useful that we have that test case, even if we don't need direct actual code changes at this time.

Okay!

https://github.com/WikipediaLibrary/TWLight/pull/397