fix(breakouts): failed to end breakout sessions

packages/@webex/plugin-meetings/src/locus-info/index.ts

@@ -93,9 +93,10 @@ export default class LocusInfo extends EventsScope {
    * Does a Locus sync. It tries to get the latest delta DTO or if it can't, it falls back to getting the full Locus DTO.
    *
    * @param {Meeting} meeting
+   * @param {boolean} isLocusUrlChanged
    * @returns {undefined}
    */
-  private doLocusSync(meeting: any) {
+  private doLocusSync(meeting: any, isLocusUrlChanged: boolean) {
     let isDelta;
     let url;
     let meetingDestroyed = false;
@@ -172,6 +173,14 @@ export default class LocusInfo extends EventsScope {
           return;
         }
 
+        // When the locus url changed, if the participants from locus sync response are empty, add the participants from workingCopy to the new locus,
+        // otherwise the participants info will be lost after the breakout session ends.
+        if (isLocusUrlChanged) {
+          if (!res.body.participants?.length) {
+            res.body.participants = this.locusParser.workingCopy.participants;
+          }
+        }
+
         if (isDelta) {
           if (res.body.baseSequence) {
             meeting.locusInfo.handleLocusDelta(res.body, meeting);
@@ -217,6 +226,7 @@ export default class LocusInfo extends EventsScope {
    */
   applyLocusDeltaData(action: string, locus: any, meeting: any) {
     const {DESYNC, USE_CURRENT, USE_INCOMING, WAIT, LOCUS_URL_CHANGED} = LocusDeltaParser.loci;
+    const isLocusUrlChanged = action === LOCUS_URL_CHANGED;
 
     switch (action) {
       case USE_INCOMING:
@@ -228,7 +238,7 @@ export default class LocusInfo extends EventsScope {
         break;
       case DESYNC:
       case LOCUS_URL_CHANGED:
-        this.doLocusSync(meeting);
+        this.doLocusSync(meeting, isLocusUrlChanged);
         break;
       default:
         LoggerProxy.logger.info(

packages/@webex/plugin-meetings/src/locus-info/parser.ts

@@ -728,13 +728,19 @@ export default class Parser {
         break;
 
       case USE_INCOMING:
-      case LOCUS_URL_CHANGED:
         // update working copy for future comparisons.
         // Note: The working copy of parser gets updated in .onFullLocus()
         // and here when USE_INCOMING or LOCUS_URL_CHANGED locus.
         this.workingCopy = newLoci;
         break;
 
+      case LOCUS_URL_CHANGED:
+        // update working copy
+        // and reset the sequence in workingCopy so that the sequence value from locus sync response will be always "newer"
+        this.workingCopy = newLoci;
+        this.workingCopy.sequence.entries = [];
+        break;
+
       case WAIT:
         // we've taken newLoci from the front of the queue, so put it back there as we have to wait
         // for the one that should be in front of it, before we can process it

packages/@webex/plugin-meetings/test/unit/spec/locus-info/index.js

@@ -2367,12 +2367,20 @@ describe('plugin-meetings', () => {
         });
       });
 
-      it('applyLocusDeltaData handles LOCUS_URL_CHANGED action correctly', () => {
+      it('applyLocusDeltaData handles LOCUS_URL_CHANGED action correctly', async () => {
         const {LOCUS_URL_CHANGED} = LocusDeltaParser.loci;
-        const fakeDeltaLocus = {id: 'fake delta locus'};
+        const fakeDeltaLocus = {
+          url: 'new loci url',
+          participants: [],
+        };
+        const fakeParticipants = [
+          {participantId: 'participant id 1'},
+          {participantId: 'participant id 2'},
+        ]
+        const res = {body: fakeDeltaLocus};
         const meeting = {
           meetingRequest: {
-            getLocusDTO: sandbox.stub().resolves({body: fakeDeltaLocus}),
+            getLocusDTO: sandbox.stub().resolves(res),
           },
           locusInfo: {
             handleLocusDelta: sandbox.stub(),
@@ -2382,10 +2390,15 @@ describe('plugin-meetings', () => {
 
         locusInfo.locusParser.workingCopy = {
           syncUrl: 'current sync url',
+          participants: fakeParticipants,
         };
 
         locusInfo.applyLocusDeltaData(LOCUS_URL_CHANGED, fakeLocus, meeting);
+
+        await testUtils.flushPromises();
+
         assert.calledOnceWithExactly(meeting.meetingRequest.getLocusDTO, {url: 'current sync url'});
+        assert.equal(res.body.participants, fakeParticipants)
       });
 
       describe('edge cases for sync failing', () => {

packages/@webex/plugin-meetings/test/unit/spec/locus-info/parser.js

@@ -253,7 +253,8 @@ describe('locus-info/parser', () => {
     });
 
     it('replaces current loci when the locus URL changes and incoming sequence is later, even when baseSequence doesn\'t match', () => {
-      const {USE_INCOMING} = LocusDeltaParser.loci;
+      const {LOCUS_URL_CHANGED} = LocusDeltaParser.loci;
+      sandbox.stub(LocusDeltaParser, 'compare').returns(LOCUS_URL_CHANGED);
 
       parser.queue.dequeue = sandbox.stub().returns(NEW_LOCI);
       parser.onDeltaAction = sandbox.stub();
@@ -262,7 +263,10 @@ describe('locus-info/parser', () => {
 
       parser.processDeltaEvent();
 
-      assert.equal(parser.workingCopy, NEW_LOCI);
+      assert.deepEqual(parser.workingCopy, {
+        ...NEW_LOCI,
+        sequence: {entries: []}
+      });
     });
 
     it('does not replace current loci when the locus URL changes but incoming sequence is not later', () => {