The scope of Model-Driven Engineering is not limited to Model-Based Development (MBD), i.e. the generation of code from system models, but involves also Model-Based Testing (MBT), which is the automatic generation of efficient test procedures from corresponding test models. Both MBD and MBT include activities such as model creation, model checking, and use of model compilers for the generation of system/test code. By reusing these common activities, the efficiency of MBT can be significantly improved for those organizations which have already adopted MBD, since one of the major efforts in MBT is the creation of test models. In this work, we propose to exploit modeling activity efforts by deriving test models from system models. In this respect, we present a case study in which the Executable and Translatable UML system models are used for automatically generating test models in the QTronic Modeling Language using horizontal model transformations. In turn, the derived artefacts can be used to produce test cases which result to be appropriate for the system under development.