Testing timed automata

We present a generalization of the classical theory of testing for Mealy machines to a setting of dense real-time systems. A model of timed I/O automata is introduced, inspired by the timed automaton model of Alur and Dill, together with a notion of test sequence for this model. Our main contributions is a test suite derivation algorithm for black-box conformance testing of timed I/O automata. Black-box testing amounts to checking whether an implementation conforms to a specification of its external behavior, by means of a set of tests derived solely from specification. The main problem is to derive a finite set of tests from a possibly infinite, dense time transition system representing the specification. The solution is to reduce the dense time transition system to an appropriate finite discrete subautomaton, the grid automaton, which contains enough information to completely represent the specification from a test perspective. Although the method results in a test suite of high exponential size and cannot be claimed to be of practical value, it gives the first algorithm that yields a finite and complete set of tests for dense real-time systems. (C) 2001 Elsevier Science B.V. All rights reserved.