Test Generation with Inputs, Outputs and Repetitive Quiescence

This paper studies testing based on labelled transition systems, using the assumption that implementations communicate with their environment via inputs and outputs. Such implementations are formalized by restricting the class of transition systems to those systems that can always accept input actions, as in Input/Output Automata. Implementation relations, formalizing the notion of correctness of these implementations with respect to labelled transition system specifications, are defined analogous to the theories of testing equivalence and preorder, and refusal testing. A test generation algorithm is given which is proved to produce a sound and exhaustive test suite from a specification, i.e., a test suite that fully characterizes the set of correct implementations.