Web services have been gaining popularity since the introduction of Service-oriented architecture and cloud computing. With more and more legacy systems migrating to service-oriented architectures and the cloud, an urgent need for proper testing techniques is becoming apparent. This paper provides an overview of the current state of research into testing of web services. To understand this subject, we conducted a systematic mapping. The results suggest that research into testing web services is still in its early stages. We provide recommendations about holes in existing research that need to be addressed and directions for future research that will have maximum novelty and potential for impact on the field.