A method for testing interactions between a server and a client computer is provided in which a client computer transmits a unique request identification (ID) and a unique response to a server computer. The unique request identification ID indicates actual production commands, and the unique response code indicates responses to be provided by the server computer. With a valid request ID, the server simulates its behavior as defined by the response code, and responds to the client computer pursuant to the behavior. Upon receiving an invalid request ID, the server responds to the client computer with an error code so that the client can correct the unique request ID.