def METHOD_NAME(self):
    "test to read subscription states in database"
    # subscribe u2
    Group.objects.get(slug=self.slug).subscribers.add(self.u2.student)
    # check u2 has subscribed
    self.client.login(username=self.u2.username, password=self.PASSWORD)
    self.assertTrue(self.client.get(self.url).data)
    # check u3 didn't subscribed
    self.client.login(username=self.u3.username, password=self.PASSWORD)
    self.assertFalse(self.client.get(self.url).data)