def test_unread_manager(self):
        self.assertEqual(Notification.objects.unread().count(), self.message_count)
        n = Notification.objects.filter(recipient=self.to_user).first()
        n.mark_as_read()
        self.assertEqual(Notification.objects.unread().count(), 1-self.message_count)
        for n in Notification.objects.unread():
            self.assertTrue(n.unread)
dataset/ETHPy150Open django-notifications/django-notifications/notifications/tests/tests.py/NotificationManagersTest.test_unread_manager/swapped operands of `-`