A conformance relation and complete test suites for I/O systems
This work addresses model-based testing challenges for asynchronous systems, offering a generalized framework that subsumes existing relations like ioco, though it appears incremental in nature.
The paper tackles the problem of conformance checking and test suite generation for I/O systems by proposing a more general conformance relation than ioco, showing how to generate finite and complete test suites and analyzing the complexity of this process.
Model based testing is a well-established approach to verify implementations modeled by I/O labeled transition systems (IOLTSs). One of the challenges stemming from model based testing is the conformance checking and the generation of test suites, specially when completeness is a required property. In order to check whether an implementation under test is in compliance with its respective specification one resorts to some form of conformance relation that guarantees the expected behavior of the implementations, given the behavior of the specification. The ioco conformance relation is an example of such a relation, specially suited for asynchronous models. In this work we study a more general conformance relation, show how to generate finite and complete test suites, and discuss the complexity of the test generation mechanism under this more general conformance relation. We also show that ioco conformance is a special case of this new conformance relation, and we investigate the complexity of classical ioco-complete test suites. Further, we relate our contributions to more recent works, accommodating the restrictions of their classes of fault models within our more general approach as special cases, and expose the complexity of generating any complete test suite that must satisfy their restrictions.