Inhalt:
Model-based testing attempts to generate test cases from a model focusing on relevant aspects of a given system under consideration (SUC). When SUC becomes too large to be modeled in a single step, existing design techniques usually require a modularization of the modeling process. Thereby, the refinement process results in a hierarchical decomposition of the SUC in several hierarchical layers. Conventional testing requires the refined components be completely replaced by these subcomponents for test case generation. We present a new test case generation strategy based on the different layers of the model to reduce (i) the number of test cases, and thus (ii) the costs of test case generation and test execution. A case study based on a complex application component of a large web-based commercial system validates the approach and discusses its characteristics regarding the number of test cases and their fault detection ability. Surprisingly, most of the faults could be detected by a considerably reduced test case set.