def test_hidden_link(self):
        req = get_request_with_user('none')
        url = "http://s.ss.edu"
        link = add_hidden_link(req, url)
        self.assertEquals(link.url, url)
        # second time
        link1 = add_hidden_link(req, url)
        self.assertEquals(link.pk, link1.pk)

        self.assertIsNotNone(delete_hidden_link(req, link.pk))
        # second time
        self.assertIsNone(delete_hidden_link(req, link.pk))