pythonunit-testingmagicmock

Prevent calling actual function when using mock.MagicMock


I have a model:

class Evaluation(models.Model):
   def abc(self):
      #some logic here
      return something

Say, I have another function which uses this:

def filter_graded(evaluations):
    return filter(lambda x: x.is_completely_graded(), evaluations)

Now when I am writing test for filter_graded method, I mock is_completely_graded to return true/false for some instances. Instead of respecting the mock, the test calls actual is_completely_graded. How can I solve this?

My test looks like:

def test_filter_graded(self):
    eval1 = G(Evaluation)
    eval2 = G(Evaluation)
    eval1.is_completely_graded = mock.MagicMock(return_value=True)
    eval2.is_completely_graded = mock.MagicMock(return_value=False)
    filter_graded(Evaluation.objects.all())
    self.assertEqual(len(result), 1)

Solution

  • You are not passing in mocked objects. You are passing in real data:

    filter_graded(Evaluation.objects.all())
    

    Nowhere did you mock out Evaluation or Evaluation.objects or Evaluation.objects.all().

    If all your code does is look for objects with a is_completely_graded method, just pass in mocks as the sequence, no need to any ORM queries:

    def test_filter_graded(self):
        eval1 = mock.MagicMock()
        eval2 = mock.MagicMock
        eval1.is_completely_graded.return_value = True
        eval2.is_completely_graded.return_value = False
        filter_graded([eval1, eval2])
        self.assertEqual(len(result), 1)