Defining and generating multi-level and uncertainty-wise test oracles for cyber-physical systems

Pablo Valle, Aitor Arrieta, Liping Han, Shaukat Ali, Tao Yue

Abstract: Cyber-physical systems (CPSs) blend digital and physical processes. CPS software is the key to realizing their functionalities. This software needs to evolve to deal with different aspects, such as the implementation of new functionalities or bug fixes. Because of this, design–operation methods, colloquially known as “DevOps,” are paramount to be adopted within these systems. During DevOps phases, automating test execution at design time is a key enabler of streamlined software development and software quality improvement. Likewise, monitoring whether a CPS is behaving as expected at operation is similarly important. In DevOps, test oracles play an important role in enabling automated testing, ensuring the reliability of software deployments, providing feedback to developers, etc. However, defining and generating test oracles in the context of DevOps practices in CPSs need to accommodate aspects specific to CPSs, such as their time-continuous behavior and inherent uncertainties. To this end, in this paper, we propose a domain-specific language (DSL) to ease the definition of test oracles and an automated solution for generating a microservice encapsulating the defined test oracles, which is compatible with a DevOps ecosystem for CPSs. We evaluated our DSL with two industrial case study systems and 9 open-source CPSs. Our evaluation results suggest that our DSL can model around 98% of the requirements of these systems through test oracles. Furthermore, it is possible to generate a microservice to be applicable at different test levels within less than 20 min, being fast enough to be adopted in practice.