Abstract <p>Microservice architecture (MSA) has emerged as a significant software architecture in both industry and academia, garnering attention as a key research area. MSA offers numerous benefits, such as facilitating independent development, testing, and system deployment. However, its distributed characteristics introduce various challenges. Testing microservices presents diverse challenges derived from complex dependencies, diverse execution environments, and different development teams, which lessen the effectiveness of conventional testing methods. Through a systematic literature review, we aim to present an overview of various testing strategies, testing tools, innovative testing solutions, and associated challenges. Our research includes academic resources from IEEE Xplore, ACM Digital Library, ScienceDirect, SpringerLink, and Wiley Online Library. From this research, we identified 76 primary studies, which we analyzed through thematic synthesis. Our analysis yielded 16 distinct testing strategies for microservices-based systems, accompanied by 19 distinct categories of proposed solutions for microservices testing. Furthermore, we compiled a total of 95 relevant tools for testing microservices. We also documented 22 distinct categories of challenges specific to testing microservices-based systems, including but not limited to automated testing, performance evaluation, and the creation of MSA-based testing environments. This study aims to serve as a resource for software engineering professionals and researchers interested in microservices testing.</p>