This paper addresses one of the major problems of SOA software development: the lack of support for testing complex service-oriented systems. The research community has developed various means for checking individual Web services but has not come up with satisfactory solutions for testing systems that operate in service-based environments and, therefore, need realistic testbeds for evaluating their quality. We regard this as an unnecessary burden for SOA engineers. As a proposed solution for this issue, we present the Genesis2 testbed generator framework. Genesis2 supports engineers in modeling testbeds and programming their behavior. Out of these models it generates running instances of Web services, clients, registries, and other entities in order to emulate realistic SOA environments. By generating real testbeds, our approach assists engineers in performing runtime tests of their systems and particular focus has been put on the framework's extensibility to allow the emulation o...