Worked on the increments/qiita-cli repository to modernize testing assertions and improve overall test reliability. Focused on refactoring unit tests by updating them to use newer Jest matchers, specifically toHaveBeenCalledWith and toHaveBeenCalledTimes, across several core test files. This approach standardized the testing syntax, reduced test flakiness, and accelerated feedback on code changes, ultimately increasing confidence in future releases. The work was implemented in a single commit, maintaining existing coverage while enhancing maintainability and preparing the codebase for easier future refactors. Utilized TypeScript and Jest, with a strong emphasis on refactoring and testing best practices throughout the process.