Developed and delivered end-to-end tests for the Msearch API within the opensearch-project/opensearch-api-specification repository, focusing on multi-search functionality across books and movies indices. The work involved designing deterministic test data setup and comprehensive result verification to ensure reliable validation of multi-request workflows. By integrating these tests with the existing test harness, the developer enabled faster continuous integration feedback and reduced the risk of regressions. The approach emphasized quality and reliability, establishing a foundation for future multi-index testing. Key technologies and skills demonstrated included API testing, YAML for test definitions, and automation best practices tailored to search API validation.