Zhaoyan worked on the LifeSG/react-design-system repository, focusing on improving the reliability of time-based tests for React components. By introducing fake timers and making requestAnimationFrame synchronous, Zhaoyan standardized the test setup for date-range-input and ensured deterministic test runs across components, addressing asynchronous issues with libraries such as floating-ui. The work involved broad mocking of requestAnimationFrame and careful use of Jest for testing, leveraging both JavaScript and TypeScript. These changes reduced test flakiness and improved CI stability, reflecting a thoughtful approach to cross-component test infrastructure. The depth of the work lay in its targeted, system-wide impact on test reliability.