'Test test_get_prerequisite_milestone_returns_none'

@patch('openedx.core.lib.gating.api.log.warning')
def test_get_prerequisite_milestone_returns_none(self, mock_log):

    prereq = gating_api._get_prerequisite_milestone(self.seq1.location)
    self.assertIsNone(prereq)
    self.assertTrue(mock_log.called)
