Compositional ioco using model-based mocking

Model-based testing is a compelling method for the end-to-end testing of microservices. However, when testing with a large number of services, state space explosion is a common problem. It is especially a problem since input-output conformance (ioco) is not compositional. We developed a novel and theoretically grounded testing method called model-based mocking (MBM) to end-to-end test microservice systems compositionally. We tested the MBM method using the Axini Modeling platform by inserting 20 mutants into an example microservice system. In our set of inserted bugs, MBM found more than half of the bugs faster compared to other methods and was slower for none of the bugs.