Context-aware systems (a.k.a. CASs) integrate cyber and physical space to provide adaptive functionalities in response to changes in context. Building context-aware systems is challenging due to the uncertain running environment. Therefore, many input validation approaches have been proposed to protect context-aware systems from uncertainty and keep them executing safely. However, in contrast to context-aware systems' prevailing in physical environments, most of those academic solutions (83%) are purely evaluated in simulated environments. In this article, we study whether this evaluation setting could lead to biased conclusions. We build a testing platform, RM-Testing, based on DJI RoboMaster robot car, to conduct the physical-environment based experiments. We select three up-to-date input validation approaches, and compare their performance in the simulated environment and in the physical environment. The experimental results show that all three approaches' performance in simulated environments (improving task success rate by 82% compared with the system without the support of input validation) does differ from their performance in a physical environment (improving the task success rate by 50%). We also recognize three factors (scenario setting, physical platform and environmental model) that affect the performance of input validation approaches, based on an execution model of the context-aware system.

Key words: context-aware system; input validation; self-driving car; testing infrastructure;