Cloud service testing ensures that services run properly and meet the Service Level Agreement (SLA) requirements. However, performance problems of a cloud service, such as the availability and reliability, are difficult to diagnose because these issues might be caused from different system components. To solve these problems, this study proposes an architecture for testing environment configuration and quality estimation for both of fault diagnosis and bottleneck detection. The proposed system has two components: offline testing and online management. In offline testing, target service are tested by using the proposed testing module and corresponding metrics are collected for further analysis. The analyzed results which are separated between fault diagnosis and bottleneck detection will be stored in knowledge databases. Finally, online management module will automatically suggest how to do when facing this kind of problem according to knowledge based diagnosis.