WPT details: https://cs.chromium.org/chromium/src/third_party/blink/web_tests/external/wpt/webrtc/RTCRtpTransceiver-stop.html This has sufficient test coverage, though there is room for more and better tests. This would be added as part of implementing it.
Transceivers allow the sending and/or receiving of media in WebRTC. Stopping a transceiver makes it permanently inactive.
Stopping a transceiver allows freeing its network port, encoder and decoder resources. This also makes its m= section in the SDP reusable by future transceivers, preventing the SDP from growing indefinitely as transceivers are added and removed. This is part of "Perfect Negotiation", which makes signaling in WebRTC race-free and less error-prone. For more details, see https://docs.google.com/presentation/d/1xcvf0udNeSH7s1FOY7RRqr1dEFvokZjn-MZPjwy3iXQ/edit?usp=sharing.