Worked on enhancing the testing infrastructure for the Esri/arcgis-rest-js repository by migrating the arcgis-rest-places package tests from Karma to Vitest. This migration leveraged JavaScript and TypeScript to enable faster and more reliable test execution, directly addressing CI flakiness and improving developer feedback cycles. Updated test mocks to align with new token nomenclature, ensuring authentication flows were accurately validated, and removed unused imports to streamline the test suite. Maintained test coverage throughout the transition while documenting changes and preparing CI notes, laying the groundwork for more robust feature development and ongoing improvements to the repository’s testing framework.