Developed and delivered a comprehensive OpenAPI3 rendering test suite for the http4k/http4k repository, focusing on validating OpenAPI specification generation using the Moshi JSON library. The approach centered on resource-based validation, where generated OpenAPI specs were compared against approved JSON resources to ensure correctness and guard against regressions. Leveraging Kotlin and test-driven development practices, the work introduced new test classes and curated resource files, enhancing test coverage and enabling earlier detection of rendering issues. This addition improved feedback cycles and increased confidence in the quality of OpenAPI rendering, contributing to more robust and reliable API documentation workflows within the project.