From Test Purposes to Asynchronous Test Cases

In this paper, we investigate the problem of constructing a test case for a given test purpose and specification modelled by input/output transition systems (IOTS). The communication between the tester and the implementation under test is assumed to be asynchronous, performed via queues. Differently from synchronous tests, when issuing verdicts, asynchronous tests should take into account the distortion caused by the queues in the observed interactions. We propose an algorithm which constructs a sound test case, by transforming the test purpose prior to composing it with the specification without queues, mitigating the state explosion problem which usually occurs when queues are directly involved in the composition. Experimental results confirm the resulting state space reduction. The proposed approach can also be used to obtain sound asynchronous tests from synchronous tests. We identify a class of IOTS specifications for which synchronous and asynchronous tests coincide.