On the Generation of Input Space Model for Model-Driven Requirements-Based Testing

Safety Critical Software (SCS) are characterized by their complex specifications with a high number of requirements due to their certification constraints. For such systems, requirements can be specified semi-formally using Controlled Natural Language (CNL) to mitigate the inherent ambiguity of natural language, and to be understandable by certification agents. Requirements serve as artifacts for software testing, where Combinatorial Interaction Testing (CIT) emerges as a relevant testing technique for SCS. CIT requires as a first step the generation of an Input Space Model (ISM) from input specifications. In this paper, we propose an approach that leverages Model-Driven Engineering (MDE) techniques for the generation of ISM from semi-formal CNL requirements constrained by templates that are specified by template models. To automatically generate the ISM, we define rules that map the template models to a generic input space model. The generated ISMs include test parameters, their test values, and inter-input constraints. Our approach ensures traceability between the generated ISM and the originating requirements, which is crucial for the certification of SCSs. We implemented our approach, and we evaluated it through a case study from the avionics domain. The case study shows that our approach can support the DO-178C certification needs in terms of requirements-based testing and provides multiple advantages over manual modeling.