Large-scale and complex distributed systems are increasingly implemented as SOAs. These comprise diverse types of components, e.g., Web services, registries, workflow engines, and services buses, that interact with each others to establish composite functionality. The drawback of this trend is that testing of complex SOAs becomes a challenging task. During the development phase, testers must verify the system's correct functionality, but often do not have access to adequate testbeds. In this paper, we present an approach for solving this issue. We combine the Genesis2 testbed generator, that emulates SOA environments, with Cafe, a framework for provisioning of component-based applications in the cloud. Our approach allows to model large-scale service-based testbed infrastructures, to specify their behavior, and to deploy these automatically in the cloud. As a result, testers can emulate required environments on-demand for evaluating SOAs at runtime.