Software testing based on SDL specifications with save

The signal save construct is one of the features distinguishing SDL from traditional high-level specification and programming languages. However, this feature increases the difficulties of testing SDL-specified software. We present a testing approach consisting of the following three phases: SDL specifications are first abstracted into finite state machines with save constructs, called SDL-machines; the resulting SDL-machines are then transformed into equivalent finite state machines without save constructs if this is possible; and, finally, test cases are selected from the resulting finite state machines. Since there are many existing methods for the first and third phases, we mainly concentrate upon the second phase and come up with a method of transforming SDL-machines into equivalent finite state machines, which preserve the same input/output relationship as in the original SDL-machines. The transformation method is useful not only for testing but also for verifying SDL-specified software