Translating EULYNX SysML Models into Symbolic Transition Systems for Model-Based Testing of Railway Signaling Systems

The EULYNX Consortium is a European initiative by 13 infrastructure managers to standardize interfaces of railway signaling systems. The consortium creates specifications based on semi-formal SysML models. In this paper, we research the feasibility of using the EULYNX SysML models for Model-Based Testing (MBT), which contributes to higher quality specifications and more efficient conformance testing of system implementations. MBT promotes safety, which is one of the most important aspects of railway signaling systems. Our approach is to translate EULYNX SysML models to Symbolic Transition Systems (STS) and to use the STS for MBT. We utilize the Axini Modeling Language (AML) and the Axini Modeling Platform (AMP), which are used by ProRail. As our System Under Test (SUT) we use a software simulation of the EULYNX point subsystem, used by EULYNX developers. We revealed several non-conforming behaviors of the SUT which shows that interface specifications like EULYNX benefit from the application of MBT. However, we observe that better advantage of MBT can be taken if EULYNX SysML specifications abstracted from implementation details, which is currently not the case.