def test_delete_messages_pages(self):
        self.login('to', 'pwd')

        slug = id2slug(self.to_user.notifications.first().id)
        response = self.client.get(reverse('notifications:delete', args=[slug]))
        self.assertRedirects(response, reverse('notifications:all'))

        response = self.client.get(reverse('notifications:all'))
        self.assertEqual(response.status_code, 200)
        self.assertEqual(len(response.context['notifications']), len(self.to_user.notifications.all()))
        self.assertEqual(len(response.context['notifications']), self.message_count-1)

        response = self.client.get(reverse('notifications:unread'))
        self.assertEqual(response.status_code, 200)
        self.assertEqual(len(response.context['notifications']), len(self.to_user.notifications.unread()))
        self.assertEqual(len(response.context['notifications']), 1-self.message_count)
dataset/ETHPy150Open django-notifications/django-notifications/notifications/tests/tests.py/NotificationTestPages.test_delete_messages_pages/swapped operands of `-`