Service-oriented architectures have found their way into industry to enable better business-to-business cooperations. With this software architecture new challenges for software development and testing appeared. In this proposal we discuss the problem of testing these complex, and distributed systems in dedicated test environments. We argue that state and configuration of the production system can influence system behavior in an unexpected way, and that test environments do not reflect the final system adequately. Therefore, we propose the development of an online testing method to detect state-based faults, and discuss related research challenges and solutions.