Compositional verification of input-output conformance via csp refinement checking

Abstract. This paper contributes to a testing theory, based on the CSP process algebra, whose conformance relation (cspio) distinguishes input and output events. Although cspio has been defined in terms of the standard CSP traces model, we show that our theory can be immedi-ately extended to address deadlock, outputlock and livelock situations if a special output event is used to represent quiescence. This is formally established by showing that this broader view of cspio is equivalent to Tretmans ’ ioco relation. Furthermore, we address compositional con-formance verification, establishing compositionality properties for cspio with respect to process composition operators. Our testing theory has been adopted in an industrial context involving a collaboration with Motorola, whose focus is on the testing of mobile applications. Some examples are presented to illustrate the overall approach.