Abstract
One of the strengths of using a stream X-machine to specify a system is that, under certain well defined conditions, it is possible to produce a test set that is guaranteed to determine the correctness of the implementation. This testing method assumes that the processing functions are correctly implemented, therefore it only tests the integration of the processing functions implementations into the system implementation. This paper uses a case study to illustrate how this method can be extended so that it will no longer require the implementations of the processing functions to be proved correct before the actual system testing can take place. Instead, the testing of the processing functions is performed along with the integration testing.