Fault Detection in Timed FSM with Timeouts by SAT-Solving

Abstract

Faults in safety critical real-time systems are not only logical, but they can correspond to violations of timing constraints. They must be detected to avoid system failures with adverse consequences. Developing efficient fault detection techniques for varieties of system models is still challenging. In this paper, we deal with fault detection for timed finite state machines with timeouts (TFSMs-T). TFSM-T is an extension of FSM to model timing constraints in safety-critical real-time systems. We lift a fault detection approach developed for FSM to generate tests detecting both logical faults and violations of time constraints in TFSMs-T. The approach is based on constraint solving and uses mutation machines to represent domains of faulty implementations (mutants) of a specification TFSMs-T. It also avoids enumerating the implementations one by one. We develop a prototype tool and we conduct experiments to evaluate the scalability of the proposed methods.