We present a framework for model-level testing of behavioral UML models. For automatic test generation, we use planner algorithms to deal with the complexity of UML models. Our approach is characterized by an automatic and metamodeldriven transformation from UML statecharts to a tool independent representation of planner algorithms from which the input language of concrete planner tools can be easily derived. As a result, UML based system models can be tested in an early phase of the design prior to implementation.