Automated system testing of an automatic train protection system

摘要

The testing of safety critical software is becoming more and more automated. Automated testing has the advantage that the tests can be carried out much more frequently and with more numerous test cases. For low level unit testing, there are several good tools available, such as Aunit. For system testing, however, the test framework normally has to be specifically tailored for each project, since it has to deal with external interfaces, e.g. man-machine-interfaces, and sensor and control interfaces. For efficient operation, it is desirable that an automated framework for system testing shall be able to serve both in a pure software setup, where most of the development is done, and in a hardware set-up, which is as close as possible to the environment where the product shall operate. This paper describes an automated system testing framework for a SIL 4 safety critical train protection system. The testing framework can be used both in the pure SW setup and in the HW set-up, and is able to extract its test cases from readable Test Specification documents and also produce high quality Test Protocol documents. Approximately 98% of the system tests have been automated in this project. The project in question is the development of STM's (Specific Transmission Modules) for Sweden, Norway and Finland. The STM's carry out train protection on national equipped lines - lines that are not equipped with the ERTMS (European Rail Transport Management System). A total of approximately 1300 test scenarios are executed by the automated testing framework.