Variability-intensive systems (VIS) form a large and heterogeneous class of systems whose behaviour can be modified by enabling or disabling predefined features. Variability mechanisms allows the adaptation of software to the needs of their users and the environment. However, VIS verification and validation (VV) is challenging: the combinatorial explosion of the number of possible behaviours and undesired feature interactions are amongst such challenges. To tackle them, Featured Transitions Systems (FTS) were proposed a decade ago to model and verify the behaviours of VIS. In an FTS, each transition is annotated with a combination of features determining which variants can execute it. An FTS can model all possible behaviours of a given VIS. This compact model enabled us to create efficient VV algorithms taking advantage of the behaviours shared amongst features resulting in a reduction of the VV effort by several orders of magnitude. In this paper, we will cover the formalism, its applications and sketch promising research directions.@en

Uniform or near-uniform generation of solutions for large satisfiability formulas is a problem of theoretical and practical interest for the testing community. Recent works proposed two algorithms (namely UniGen and QuickSampler) for reaching a good compromise between execution time and uniformity guarantees, with empirical evidence on SAT benchmarks. In the context of highly-configurable software systems (e.g., Linux), it is unclear whether UniGen and QuickSampler can scale and sample uniform software configurations. In this paper, we perform a thorough experiment on 128 real-world feature models. We find that UniGen is unable to produce SAT solutions out of such feature models. Furthermore, we show that QuickSampler does not generate uniform samples and that some features are either never part of the sample or too frequently present. Finally, using a case study, we characterize the impacts of these results on the ability to find bugs in a configurable system. Overall, our results suggest that we are not there: more research is needed to explore the cost-effectiveness of uniform sampling when testing large configurable systems.@en