webrtc/RTCPeerConnection-setLocalDescription-pranswer-parameterless.html

<!doctype html>
<meta charset=utf-8>
<title>RTCPeerConnection.prototype.setLocalDescription pranswer without sdp</title>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script src="RTCPeerConnection-helper.js"></script>
<script>
'use strict';

// webrtc-pc, setLocalDescription: when the sdp is missing or empty and the
// type is "pranswer" or "answer", [[LastCreatedAnswer]] is used. When the type
// is missing too, it is "offer" in "stable", "have-local-offer" and
// "have-remote-pranswer", and "answer" otherwise.

async function haveRemoteOffer(t) {
  const offerer = new RTCPeerConnection();
  const answerer = new RTCPeerConnection();
  t.add_cleanup(() => {
    offerer.close();
    answerer.close();
  });
  offerer.addTransceiver('audio');
  await offerer.setLocalDescription();
  await answerer.setRemoteDescription(offerer.localDescription);
  return [offerer, answerer];
}

promise_test(async t => {
  const [, answerer] = await haveRemoteOffer(t);
  const answer = await answerer.createAnswer();
  await answerer.setLocalDescription({type: 'pranswer', sdp: ''});
  assert_equals(answerer.signalingState, 'have-local-pranswer');
  assert_equals(answerer.pendingLocalDescription.type, 'pranswer');
  // assert_true() is used rather than assert_equals(), otherwise this gets
  // very noisy.
  assert_true(answerer.pendingLocalDescription.sdp == answer.sdp,
    'pendingLocalDescription.sdp == answer.sdp');
}, 'setLocalDescription({type: "pranswer", sdp: ""}) uses [[LastCreatedAnswer]]');

promise_test(async t => {
  const [, answerer] = await haveRemoteOffer(t);
  await answerer.setLocalDescription({type: 'pranswer'});
  assert_equals(answerer.signalingState, 'have-local-pranswer');
  assert_equals(answerer.pendingLocalDescription.type, 'pranswer');
  assert_not_equals(answerer.pendingLocalDescription.sdp, '');
}, 'setLocalDescription({type: "pranswer"}) creates an answer to use');

promise_test(async t => {
  const [, answerer] = await haveRemoteOffer(t);
  await answerer.setLocalDescription({type: 'pranswer', sdp: ''});
  await answerer.setLocalDescription({type: 'pranswer', sdp: ''});
  assert_equals(answerer.signalingState, 'have-local-pranswer');
  await answerer.setLocalDescription({type: 'answer', sdp: ''});
  assert_equals(answerer.signalingState, 'stable');
  assert_equals(answerer.currentLocalDescription.type, 'answer');
  assert_equals(answerer.pendingLocalDescription, null);
}, 'setLocalDescription without sdp works for repeated pranswers and the ' +
   'final answer');

promise_test(async t => {
  const [, answerer] = await haveRemoteOffer(t);
  await answerer.setLocalDescription({type: 'pranswer'});
  // No type either: "have-local-pranswer" is not one of the states that means
  // "offer", so this is a final answer.
  await answerer.setLocalDescription();
  assert_equals(answerer.signalingState, 'stable');
  assert_equals(answerer.currentLocalDescription.type, 'answer');
}, 'Parameterless setLocalDescription() in "have-local-pranswer" is a final ' +
   'answer');

promise_test(async t => {
  const [offerer, answerer] = await haveRemoteOffer(t);
  const {sdp} = await answerer.createAnswer();
  await offerer.setRemoteDescription({type: 'pranswer', sdp});
  assert_equals(offerer.signalingState, 'have-remote-pranswer');
  // No type means "offer" here, and an offer cannot be set in this state
  // (RFC 9429 section 5.5).
  await promise_rejects_dom(t, 'InvalidStateError',
    offerer.setLocalDescription());
  assert_equals(offerer.signalingState, 'have-remote-pranswer');
}, 'Parameterless setLocalDescription() in "have-remote-pranswer" rejects ' +
   'with InvalidStateError');

</script>