Add support for group calls using MSC3401

.github/CODEOWNERS

@@ -1 +1,4 @@
 * @matrix-org/element-web
+
+/src/webrtc @matrix-org/element-call-reviewers
+/spec/*/webrtc @matrix-org/element-call-reviewers

package.json

@@ -55,13 +55,16 @@
   ],
   "dependencies": {
     "@babel/runtime": "^7.12.5",
+    "@types/sdp-transform": "^2.4.5",
     "another-json": "^0.2.0",
     "bs58": "^5.0.0",
     "content-type": "^1.0.4",
     "loglevel": "^1.7.1",
     "matrix-events-sdk": "0.0.1-beta.7",
+    "matrix-widget-api": "^1.0.0",
     "p-retry": "4",
     "qs": "^6.9.6",
+    "sdp-transform": "^2.14.1",
     "unhomoglyph": "^1.0.6"
   },
   "devDependencies": {
@@ -102,6 +105,7 @@
     "exorcist": "^2.0.0",
     "fake-indexeddb": "^4.0.0",
     "jest": "^29.0.0",
+    "jest-environment-jsdom": "^28.1.3",
     "jest-localstorage-mock": "^2.4.6",
     "jest-mock": "^29.0.0",
     "jsdoc": "^3.6.6",

spec/test-utils/flushPromises.ts

@@ -0,0 +1,28 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Jest now uses @sinonjs/fake-timers which exposes tickAsync() and a number of
+// other async methods which break the event loop, letting scheduled promise
+// callbacks run. Unfortunately, Jest doesn't expose these, so we have to do
+// it manually (this is what sinon does under the hood). We do both in a loop
+// until the thing we expect happens: hopefully this is the least flakey way
+// and avoids assuming anything about the app's behaviour.
+const realSetTimeout = setTimeout;
+export function flushPromises() {
+    return new Promise(r => {
+        realSetTimeout(r, 1);
+    });
+}