Extending Stream X-Machines to specify and test systems with timeouts

Abstract

Stream X-machines are a kind of extended finite state machine used to specify real systems where communication between the components is modeled by using a shared memory. In this paper we introduce an extension of the Stream X-machines formalism in order to specify delays/timeouts. The time spent by a system waiting for the environment to react has the capability of affecting the set of available outputs of the system. So, a relation focusing on functional aspects must explicitly take into account the possible timeouts. We also propose a formal testing methodology allowing to systematically test a system with respect to a specification. Finally, we introduce a test derivation algorithm. Given a specification, the derived test suite is sound and complete, that is, a system under test successfully passes the test suite if and only if this system conforms to the specification.