private async Task <Task> SetUpSource() { await SetUpTopology(); var streamId = await source.Join(userName); var stream = client.GetStreamProvider(Constants.FaultTolerantStreamProvider) .GetStream <StreamMessage>(streamId, Constants.FaultTolerantStreamNameSpace); //subscribe to the stream to receiver furthur messages sent to the chatroom Mock <ILogger> mockLogger = new Mock <ILogger>(); statefulStreamObserver = new StatefulStreamObserver(mockLogger.Object); await stream.SubscribeAsync(statefulStreamObserver); members = await source.GetMembers(); return(Task.CompletedTask); }