Testing (Stream) X-machines

In 1988 X-machines were proposed as a basis for a specification language and, since then, a number of further investigations have demonstrated the value of this idea. A number of classes of X-machines have been identified and studied, most importantly the class of stream X-machines. A theory of testing based on stream X-machines has also been developed. This allows the generation of test sets which, if satisfied, guarantee, under certain constraints, the correctness of implementation with respect to specification. This paper extends this theory in two ways. Firstly, it considers the general X-machine model rather than the particular stream X-machine class. Secondly, the theoretical results proved give rise to at least two different testing strategies. These results are then particularised to the stream X-machine class. Key words:Testing, Finite state machine, (stream) X-machine, Formal specification.