The publish/subscribe style is an emerging paradigm for the construction of loosely coupled systems. Yet, the verification of such systems remains difficult. We have constructed a framework called RAY for testing publish/subscribe applications. This framework is implemented as an Eclipse plug-in. In this paper, we present the detailed architecture of RAY, as well as the interaction with its supporting components. In addition to the presented architecture for a testing framework for publish/subscribe applications, the contribution of this paper includes the experience gained during the development of this framework.