'Check that course overview is cached after course published signal is sent'

def test_course_overview_cached(self):

    course_key = CCXLocator.from_course_locator(self.course.id, self.ccx.id)
    overview = CourseOverview.objects.filter(id=course_key)
    self.assertEqual(len(overview), 0)
    with mock_signal_receiver(SignalHandler.course_published) as receiver:
        self.call_fut(self.course.id)
        self.assertEqual(receiver.call_count, 3)
        overview = CourseOverview.objects.filter(id=course_key)
        self.assertEqual(len(overview), 1)
