The use of an ISO technique for conformance test specifications

The implementation of universally consistent interfaces is usually hampered by the absence of adequate conformance standards. The authors describe and review a method of producing such conformance specifications through a case study involving the ISDN customer interface. It is shown that tabular and tree combined notation (TTCN) provides an easy-to-use, structured method of writing tests. It can be readily translated into a computer language for implementation. It is ideally suited to testing state machines and provides good flexibility by declaring all the parameters, variables, and PDUs remotely from the test scripts. This allows the same test scripts to test implementations with different parameters by simply submitting a new set of declarations. TTCN does not define the degree of testing required, but it does provide a general structure that allows the test designer to define whatever tests are required in a rigorous manner