anchor.diff:       ?_assertEqual(Response2, create_response(Request, 201, <<"Very Ok!">>))
        ].
   
  -
  --spec create_ack_test_() -> list().
  -create_ack_test_() ->
  +-spec create_ack_cancel_test_() -> list().
  +create_ack_cancel_test_() ->
       ReqHeaders = [{via, <<"SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKkjshdyff">>},
                     {via, <<"SIP/2.0/UDP bob.biloxi.com;branch=z9hG4bK776asdhds">>},
                     {to, <<"Bob <sip:bob@biloxi.com>">>},
  
positive.code:                   {route, <<"<sip:bob@biloxi.com>">>},
                    {'max-forwards', 15}],
  
      ACK = #sip_request{method = 'ACK', uri = <<"sip:bob@biloxi.com">>, headers = ACKHeaders},
      [
       ?_assertEqual(parse_all_headers(ACK), parse_all_headers(create_ack(Request, Response2)))
       ].
  
  -spec helpers_test_() -> list().
  
negative.code:      ?_assertEqual(ok, validate_request(ValidRequest2)),
       ?_assertEqual({error, {invalid, contact_must_be_sips}}, validate_request(InvalidRequest2)),
       ?_assertEqual(ok, validate_request(ValidRequest3)),
  
       % Response validation
       ?_assertEqual(ok, validate_response(ValidResponse)),
  