A Systematic and Semi-Automatic Safety-Based Test Case Generation Approach Based on Systems-Theoretic Process Analysis
This addresses the problem of ensuring software safety in safety-critical systems for software and safety engineers, but it is incremental as it builds on existing STPA methods.
The paper tackles the challenge of generating safety-critical test cases for software by proposing a systematic, semi-automatic approach based on Systems-Theoretic Process Analysis (STPA) to derive test cases from safety analysis results, and demonstrates it with an Adaptive Cruise Control System prototype using a Lego-Mindstorms EV3 robot.
Software safety is a crucial aspect during the development of modern safety-critical systems. Software is becoming responsible for most of the critical functions of systems. Therefore, the software components in the systems need to be tested extensively against their safety requirements to ensure a high level of system safety. However, performing testing exhaustively to test all software behaviours is impossible. Numerous testing approaches exist. However, they do not directly concern the information derived during the safety analysis. STPA (Systems-Theoretic Process Analysis) is a unique safety analysis approach based on system and control theory, and was developed to identify unsafe scenarios of a complex system including software. In this paper, we present a systematic and semi-automatic testing approach based on STPA to generate test cases from the STPA safety analysis results to help software and safety engineers to recognize and reduce the associated software risks. We also provide an open-source safety-based testing tool called STPA TCGenerator to support the proposed approach. We illustrate the proposed approach with a prototype of a software of the Adaptive Cruise Control System (ACC) with a stop-and-go function with a Lego-Mindstorms EV3 robot.