def assertUnauthorizedLogin(self, d):
        """
        Asserts that the L{Deferred} passed in is erred back with an
        L{UnauthorizedLogin} L{Failure}.  This reprsents an invalid login for
        this TestCase.

        NOTE: To work, this method's return value must be returned from the
        test method, or otherwise hooked up to the test machinery.

        @param d: a L{Deferred} from an L{IChecker.requestAvatarId} method.
        @type d: L{Deferred}
        @rtype: L{None}
        """
        self.assertRaises(
            checkers.UnauthorizedLogin, self.assertLoggedIn, d, 'bogus value')

        Asserts that the L{Deferred} passed in is erred back with an
        L{UnauthorizedLogin} L{Failure}.  This reprsents an invalid login for
        this TestCase.

        NOTE: To work, this method's return value must be returned from the
        test method, or otherwise hooked up to the test machinery.

        @param d: a L{Deferred} from an L{IChecker.requestAvatarId} method.
        @type d: L{Deferred}
        @rtype: L{None}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_checkers.py