Bug 1824381 [wpt PR 39181] - WebRTC WPT: Test that the answer negotiates a subset of RTP header extensions, a=testonly

Automatic update from web-platform-tests
WebRTC WPT: Test that the answer negotiates a subset of RTP header extensions

as defined in JSEP
  https://www.rfc-editor.org/rfc/rfc8829.html#section-5.3.1:

  For each supported RTP header extension that is present in the offer,
  [add] an "a=extmap" line

BUG=None

Change-Id: Ic9e2195a8a6aa011c8938f8a5ef0d74055d36cc8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4369845
Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1121783}

--

wpt-commits: 10c4049e41aec3e9945381e64aa8ab638eb00a6f
wpt-pr: 39181

testing/web-platform/tests/webrtc/protocol/rtp-headerextensions.html

@@ -76,4 +76,26 @@ a=setup:actpass
   }, testcase.description + ' header extension is supported.');
 });
 
+promise_test(async t => {
+  const pc = new RTCPeerConnection();
+  t.add_cleanup(() => pc.close());
+
+  pc.addTransceiver('video');
+  const offer = await pc.createOffer();
+  const section = SDPUtils.splitSections(offer.sdp)[1];
+  const extensions = SDPUtils.matchPrefix(section, 'a=extmap:')
+    .map(line => SDPUtils.parseExtmap(line));
+  const extension_not_mid = extensions.find(e => e.uri !== 'urn:ietf:params:rtp-hdrext:sdes:mid');
+  await pc.setRemoteDescription({type :'offer', sdp: offer.sdp.replace(extension_not_mid.uri, 'bogus')});
+
+  await pc.setLocalDescription();
+  const answer_section = SDPUtils.splitSections(pc.localDescription.sdp)[1];
+  const answer_extensions = SDPUtils.matchPrefix(answer_section, 'a=extmap:')
+    .map(line => SDPUtils.parseExtmap(line));
+  assert_equals(answer_extensions.length, extensions.length - 1);
+  assert_false(!!extensions.find(e => e.uri === 'bogus'));
+  for (const answer_extension of answer_extensions) {
+    assert_true(!!extensions.find(e => e.uri === answer_extension.uri));
+  }
+}, 'Negotiates the subset of supported extensions offered');
 </script>