def test_delete_custom_link(self):
        username = 'none'
        req = get_request_with_user(username)
        url = "http://s.ss.edu"
        link = add_custom_link(req, url)
        self.assertIsNotNone(delete_custom_link(req, link.pk))
        # second time
        self.assertIsNone(delete_custom_link(req, link.pk))