Design for Testability of ERMTS Applications

Abstract

The European Rail Traffic Management System (ERTMS) represents a class of embedded software-intensive systems of systems for the management of the European rail traffic, in a scenario where interoperability between different European rail traffic infrastructures must be maintained. Due to the intrinsically safety-critical nature of ERTMS, software testing must meet the strict prescriptions imposed by the certification authorities, which often require the availability of the entire system. This potentially leads to perform the tests at a late stage of development, even though the best practices suggest that it would be more convenient to test the system incrementally since the early stages of development. This paper deals with the solution we devised to address this issue in a recent ERTMS project. We adopted a design-for-testability pattern which purposely enhances the observability and the controllability of the software under test to make it testable at any stage of development, allowing the exploitation of system tests even during component and integration testing.