// in queue.component.html
<button class="ws-shift" (click)="test()" >Test</button>


//in queue.component.ts
export class QueueComponent implements OnInit {

  constructor(private playerHanlder: PlayerHanlder) { }

  ngOnInit() {
  }

  test(){
	// when I click the button, nothing gets printed out
    this.playerHanlder.tracks$.subscribe(t=>console.log(t))
  }
}

// in playerhandler.ts

@Injectable({
  providedIn: "root"
})
export class PlayerHanlder {
  isPlaying: boolean = false;
  index: number;
  tracks$ = new ReplaySubject<any>();

  constructor(
    private playerService: PlayerService,
    private deezer: DeezerService
  ) { }

  initTracks(tracks): void {
    this.tracks$.next(tracks);
    this.playerService.init(tracks);
  }