In November 2024, Dan Castillo refactored the test suite for the fastify/fastify repository, focusing on improving reliability and maintainability. He reworked test assertions to use strict equality checks, such as deepStrictEqual and notStrictEqual, and eliminated unnecessary console logs to streamline test output. By tightening the validation of request parameter types and values, Dan addressed potential edge cases and reduced the likelihood of flaky tests. His work, implemented using JavaScript and Node.js with an emphasis on robust testing practices, enhanced the stability of continuous integration feedback and supported safer future refactors in this high-traffic core project.