Model-based protocol log generation for testing a telecommunication test harness using CLP

Within telecommunications development it is vital to have frameworks and systems to replay complicated scenarios on equipment under test, often there are not enough available scenarios. In this paper we study the problem of testing a test harness, which replays scenarios and analyses protocol logs for the Public Warning System service, which is a part of the Long Term Evolution (LTE) 4G standard. Protocol logs are sequences of messages with timestamps; and are generated by different mobile network entities. In our case study we focus on user equipment protocol logs. In order to test the test harness we require that logs have both incorrect and correct behaviour. It is easy to collect logs from real system runs, but these logs do not show much variation in the behaviour of system under test. We present an approach where we use constraint logic programming (CLP) for both modelling and test generation, where each test case is a protocol log. In this case study, we uncovered previously unknown faults in the test harness.