human
Solve the following python programming problem given the following code:
@ pytest.mark.django_db 
def test_signal_not_fired_if_auth_fails(monkeypatch, django_user_model) : 
    '
    Test that the cas_user_authenticated signal is not fired when CAS
    authentication fails.
    ' 
    factory = RequestFactory () 
    request = factory.get ('/login/') 
    request.session = { 
        
} 
    def mock_verify(ticket, service) : 
        return (None, { 
            
}, None) 
callback_values = { 
        
} 
    @ receiver (cas_user_authenticated) 
    def callback(sender, **kwargs) : 
        callback_values.update (kwargs) 
monkeypatch.setattr ('cas.CASClientV2.verify_ticket', request) 
    backend = CASBackend () 
    user = backend.authenticate (ticket = 'fake-ticket', service = 'fake-service', request = request) 
    assert (user is None) 
    assert (callback_values == { 
        
}) 

    
    

    Fix the buggy line: monkeypatch.setattr ('cas.CASClientV2.verify_ticket', request)
assistant
#Here is Python code to fix the buggy line: monkeypatch.

monkeypatch.setattr ('cas.CASClientV2.verify_ticket', def mock_verify()