Component-based software systems (CBSSs) enable modular design and reuse, but their integration poses substantial testing challenges. Integration faults often stem from interactions between components and are difficult to detect with isolated unit testing. Existing integration testing practices require significant manual effort, particularly in configuring test environments and maintaining test suites as systems evolve.This dissertation introduces the Interaction-based Integration (IBI) Testing Approach, a novel approach to automate integration testing by reusing unit test cases. The IBI testing approach comprises the IBI Metamodel, which captures structural, behavioral, and interaction expectation aspects of CBSSs, and the IBI Testing Process, which operationalizes the IBI Metamodel. The approach leverages unit test cases to derive interaction expectations, and generate so called interaction test cases, by reusing the test outputs of one unit test case as inputs for another. It thereby simulates system behavior, enabling integration testing without the need for dedicated integration test cases or environments. In contrast to existing approaches, which require dedicated integration environments and handcrafted test cases, this work enables integration validation through existing unit test artifacts.The IBI testing approach is formalized using property graphs and regular path queries. It is implemented in the InterACt tool, evaluated through a demonstration case study on a microservice system and an exploratory case study in collaboration with an industry partner. The results confirm the feasibility of the IBI Testing Approach while identifying practical limitations that guide future improvements.This work contributes a reusable integration testing model, a formalized testing process, and a tool-supported implementation that provide a novel approach to integration testing of CBSSs. The findings highlight the potential of reusing unit test cases for integration testing, while also addressing the challenges and limitations of this approach in practice.
Nils Wild (Wed,) studied this question.