On Service-to-Service Integration Testing in Microservice Systems
Lena Gregor · 2025
Microservices enable scalable and flexible software systems but introduce significant testing challenges, particularly at the interaction level between services. Traditional test adequacy criteria, such as branch coverage and traditional mutation operators are unsuitable for evaluating interactions across microservices due to their fine-grained focus and reliance on language-specific, resource-intensive methods. Despite recent advancements in end-to-end coverage metrics and mutation operators, no approach currently targets mutation testing for integration-level tests in microservice systems. This thesis acknowledges the need for a novel mutation testing approach tailored to microservice systems, leveraging a fault taxonomy derived from real-world projects and literature. The proposed tool enables runtime fault injection without requiring system redeployment, addressing the polyglot nature and high deployment costs of microservices. Preliminary results include a validated and published fault taxonomy and a prototype tool. Future work involves further refinement of the tool, comprehensive evaluations, and comparisons with traditional methods to evaluate its effectiveness and efficiency.