High Level Transition Systems of CSP Specifications: and their Application in Automated Testing

State of the art quality assurance for safety critical software systems requires formal methods for verification and testing. One of the drawbacks using formal methods to model large systems is the state explosion of transition systems generated from formal specifications. The authors present an approach to reduce the problem of state explosions using a representation of the transition system of a CSP specification, that does not require the calculation of the complete state space.Different stages of the normalisation of high level transition graphs and synchronisation terms have been developed, which can directly be used for real-time testing. To enable real-time testing with unnormalised graphs, an on-the-fly normalisation is introduced which imposes certain requirements on the CSP specification. In some cases, the test evaluation needs not to be performed in real-time. Instead it is often sufficient to do the test evaluation with a slight delay of a few seconds. For those cases a new test algorithm for a delayed test evaluation is suggested, which can be used for testing purposes based on any type of transition systems, even unnormalised systems.