fix: Duplicated channels after two notification events and not up to date channel state

Author: szuperaz

projects/stream-chat-angular/src/lib/channel.service.spec.ts

@@ -766,6 +766,33 @@ describe('ChannelService', () => {
     expect(channel.on).toHaveBeenCalledWith(jasmine.any(Function));
   }));
 
+  it(`shouldn't add channels duplicated if two notification event is received for the same channel`, fakeAsync(async () => {
+    await init();
+    const channel = generateMockChannels()[0];
+    channel.cid = 'channel';
+    channel.id = 'channel';
+    channel.type = 'messaging';
+    mockChatClient.channel.and.returnValue(channel);
+    spyOn(channel, 'watch').and.callThrough();
+    spyOn(channel, 'on').and.callThrough();
+    const spy = jasmine.createSpy();
+    service.channels$.subscribe(spy);
+    events$.next({
+      eventType: 'notification.added_to_channel',
+      event: { channel: channel } as any as Event<DefaultStreamChatGenerics>,
+    });
+    events$.next({
+      eventType: 'notification.message_new',
+      event: { channel: channel } as any as Event<DefaultStreamChatGenerics>,
+    });
+    tick();
+
+    const channels = spy.calls.mostRecent().args[0] as Channel[];
+
+    expect(channels.filter((c) => c.cid === channel.cid).length).toBe(1);
+    expect(channel.on).toHaveBeenCalledOnceWith(jasmine.any(Function));
+  }));
+
   it('should remove channel form the list if user is removed from channel', async () => {
     await init();
     let channel!: Channel<DefaultStreamChatGenerics>;

projects/stream-chat-angular/src/lib/channel.service.ts

@@ -876,21 +876,28 @@ export class ChannelService<
     }
   }
 
-  private addChannelsFromNotification(channelResponses: ChannelResponse<T>[]) {
-    const newChannels: Channel<T>[] = [];
+  private async addChannelsFromNotification(
+    channelResponses: ChannelResponse<T>[]
+  ) {
+    let newChannels: Channel<T>[] = [];
+    const watchRequests: Promise<any>[] = [];
     channelResponses.forEach((channelResponse) => {
       const channel = this.chatClientService.chatClient.channel(
         channelResponse.type,
         channelResponse.id
       );
-      void channel.watch();
-      this.watchForChannelEvents(channel);
+      watchRequests.push(channel.watch());
       newChannels.push(channel);
     });
-    this.channelsSubject.next([
-      ...newChannels,
-      ...(this.channelsSubject.getValue() || []),
-    ]);
+    await Promise.all(watchRequests);
+    const currentChannels = this.channelsSubject.getValue() || [];
+    newChannels = newChannels.filter(
+      (newChannel) => !currentChannels.find((c) => c.cid === newChannel.cid)
+    );
+    if (newChannels.length > 0) {
+      newChannels.forEach((c) => this.watchForChannelEvents(c));
+      this.channelsSubject.next([...newChannels, ...currentChannels]);
+    }
   }
 
   private removeChannelsFromChannelList(cids: string[]) {