Verification of Microservices Using Metamorphic Testing

© 2020, Springer Nature Switzerland AG. Microservices architecture is drawing more and more attention recently. By dividing the monolithic application into different services, microservices-based applications are more flexible, scalable and portable than traditional applications. However, the unique characteristics of Microservices architecture have also brought significant challenges for software verification. One major challenge is the oracle problem: in the testing of microservices, it is often very difficult to verify the test result given a test input, due to the features of wide distribution, heterogeneity, frequent changes, and numerous runtime behaviors. To tackle such a challenge, in this paper, we investigate how to apply metamorphic testing into the verification of microservices-based applications, which is a simple yet effective approach to oracle problem. Empirical studies are conducted to evaluate the performance of metamorphic testing based on real-world microservice applications, against the baseline random testing technique with a complete oracle. The results show that in the absence of oracles, metamorphic testing can deliver relatively high failure-detection effectiveness. Our work demonstrates that metamorphic testing is both applicable and effective in addressing the oracle problem for the verification of microservices, similar to many other application domains.