Improving model-based test generation by model decomposition

One of the well-known techniques for model-based test generation exploits the capability of model checkers to return counterexamples upon property violations. However, this approach is not always optimal in practice due to the required time and memory, or even not feasible due to the state explosion problem of model checking. A way to mitigate these limitations consists in decomposing a system model into suitable subsystem models separately analyzable. In this paper, we show a technique to decompose a system model into subsystems by exploiting the model variables dependency, and then we propose a test generation approach which builds tests for the single subsystems and combines them later in order to obtain tests for the system as a whole. Such approach mitigates the exponential increase of the test generation time and memory consumption, and, compared with the same model-based test generation technique applied to the whole system, shows to be more efficient. We prove that, although not complete, the approach is sound.