This chapter focuses on planning tests, analysis, scenarios, verification, validation, and regression testing to ensure the reliability and safety of systems. It outlines the importance of systematic test methodologies, including scenario-based evaluations and simulations, to verify compliance with safety requirements and validate system performance. The chapter emphasizes the role of regression testing in maintaining system integrity after updates, highlighting how agile practices and automated tools can facilitate frequent testing and quicker resolution of potential issues. These methods ensure systems meet safety standards and operate reliably in real-world conditions.