Worked on the mozilla/gecko-dev repository to implement foundational tests for WebRTC header extension exposure in RTCRtpSender and RTCRtpReceiver. Focused on validating that header extensions are correctly exposed in getParameters only after the offer/answer exchange, and absent before, establishing a baseline for parameter exposure behavior. Used JavaScript and WebRTC APIs to create end-to-end test flows, ensuring regression safety and reliable coverage for future changes. The work linked directly to two tracked bugs, providing targeted test coverage and strengthening the test suite’s ability to catch issues related to header extension handling. Emphasized thorough testing and maintainable validation processes.