Section: New Results

Model-based Testing an Interactive Music System

In the context of the Phd of Clément Poncelet, and in relation with the developments presented in Section  5.3 , we have been studying the application of model-based timed testing techniques to interactive music systems like Antescofo.

Several formal methods have been developed for automatic conformance testing of critical embedded software. The principle is to execute a real implementation under test (IUT) in a testing framework, black-box, by sending it carefully selected inputs and then observing and analyzing its outputs. In conformance model-based testing (MBT), the input and corresponding expected outputs are generated according to formal models of the IUT and the environment. The models of timed automata with inputs and outputs, and tools like the the Uppaal suite have been developed for extending such techniques to realtime systems [32] , [31] . Several procedures have been designed for addressing the task described in Section  5.3 .

The case of IMS presents important originalities compared to other MBT applications to realtime systems. On the one hand, the time model supports several time units, including the wall clock time, measured in seconds, and the time of music scores, measured in number of beats relatively to a tempo. This situation raised several new problems for the generation of test suites and their execution. On the other hand, the formal specification of the IUT’s behavior on a given score is produced automatically by a score compiler, using an intermediate representation. We rely on the realistic hypotheses that a mixed score specify completely the expected timed behavior of the IMS. Hence, our test method is fully automatic, in contrast with other approaches which generally require experts to write the specification manually. This workflow fits well in a music authoring workflow where scores in preparation are constantly evolving. We have been applying our tools to small benchmark made of characteristic scores, as well as to real mixed scores used in concerts, and some bugs in Antescofo have been identified. These results have been presented in the conference ICMC 2014 [18] and will be presented during the 30th ACM/SIGAPP Symposium On Applied Computing, track Software Verification and Testing [17] .