Synchronizable Test Sequences of Finite State Machines

The finite state machine (FSM) model is commonly used for specifying communication protocols and other types of distributed systems. With the use of multiple testers for an FSM, the synchronization between inputs from different testers becomes a problem. A synchronizable test sequence of an FSM is a test sequence for which the synchronization problem either does not exist or can be solved by communication between testers. In this paper, we consider two testing strategies for an FSM: port-based testing, which does not allow testers for the FSM to communicate with each other, and group-based testing, which divides the ports of the FSM into groups and allows the testers for ports in the same group to communicate with each other. For each type of testing, we define a necessary and sufficient condition under which a test sequence of an FSM is synchronizable and show how to generate a set of testers according to a given test sequence. Also, we discuss the issues of test sequence generation and fault detection, and present the results of some empirical studies.