IST Austria Technical Report

Model-based testing is a promising technology for black-box software and hardware testing, in which test cases are generated automatically from high-level specifications. Nowadays, systems typically consist of multiple interacting components and, due to their complexity, testing presents a considerable portion of the effort and cost in the design process. Exploiting the compositional structure of system specifications can considerably reduce the effort in model-based testing. Moreover, inferring properties about the system from testing its individual components allows the designer to reduce the amount of integration testing. In this paper, we study compositional properties of the IOCO-testing theory. We propose a new approach to composition and hiding operations, inspired by contract-based design and interface theories. These operations preserve behaviors that are compatible under composition and hiding, and prune away incompatible ones. The resulting specification characterizes the input sequences for which the unit testing of components is sufficient to infer the correctness of component integration without the need for further tests. We provide a methodology that uses these results to minimize integration testing effort, but also to detect potential weaknesses in specifications. While we focus on asynchronous models and the IOCO conformance relation, the resulting methodology can be applied to a broader class of systems

Towards Symbolic Model-Based Mutation Testing: Combining Reachability and Refinement Checking

Model-based mutation testing uses altered test models to derive test cases that are able to reveal whether a modelled fault has been implemented. This requires conformance checking between the original and the mutated model. This paper presents an approach for symbolic conformance checking of action systems, which are well-suited to specify reactive systems. We also consider nondeterminism in our models. Hence, we do not check for equivalence, but for refinement. We encode the transition relation as well as the conformance relation as a constraint satisfaction problem and use a constraint solver in our reachability and refinement checking algorithms. Explicit conformance checking techniques often face state space explosion. First experimental evaluations show that our approach has potential to outperform explicit conformance checkers.Comment: In Proceedings MBT 2012, arXiv:1202.582

Increasing and Validating the Safety and Reliability of Cyber-Physical Systems

Cyber-physical systems (CPS) like production facilities, medical devices, and modern cars play an increasingly significant role in the economic context but also in every-day life; catchphrases like “Industry 4.0” and “Mobility of the Future” are on everybody’s mind. Manufacturers and operators of such systems are highly interested in investigating and ensuring the safety and reliability of their systems."br" The security researchers of AIT Austrian Institute of Technology’s research field “Dependable Systems Engineering” (DSE) deal with the challenge of increasing the safety and reliability of cyber-physical systems since many years. The team actively engages interesting problems in both, the scientific - and production domains together with key industry partners. In this way, they not only drive scientific progress in their field of study but also keep their eyes on the practical applicability of their solutions."br" With this goal in mind, the DSE’s researchers and engineers develop tools and methodologies to address questions regarding Safe and Secure Co-Engineering. Examples include safe and secure reference architectures; methods for model-based analysis of safety-critical systems; automated test case generation; and real-time monitoring of complex systems. The group’s experts also contribute to the development of industry standards, e.g., ISO26262."br" Keywords: cyber-physical systems; safety and security; verification and validation; dependable systems engineering; model-based; automated test case generation; real-time monitorin

Compositional specifications for IOCO testing

Model-based testing is a promising technology for black-box software and hardware testing, in which test cases are generated automatically from high-level specifications. Nowadays, systems typically consist of multiple interacting components and, due to their complexity, testing presents a considerable portion of the effort and cost in the design process. Exploiting the compositional structure of system specifications can considerably reduce the effort in model-based testing. Moreover, inferring properties about the system from testing its individual components allows the designer to reduce the amount of integration testing. In this paper, we study compositional properties of the ioco-testing theory. We propose a new approach to composition and hiding operations, inspired by contract-based design and interface theories. These operations preserve behaviors that are compatible under composition and hiding, and prune away incompatible ones. The resulting specification characterizes the input sequences for which the unit testing of components is sufficient to infer the correctness of component integration without the need for further tests. We provide a methodology that uses these results to minimize integration testing effort, but also to detect potential weaknesses in specifications. While we focus on asynchronous models and the ioco conformance relation, the resulting methodology can be applied to a broader class of systems