it('should tick', fakeAsync(() => {
    const firstDate = new Date();
    tick(30000);
    const secondDate = new Date();
    expect(secondDate.getTime() - firstDate.getTime()).toBe(30000);
  }));

export class UserTaskTrackerService {
  TaskExpired = new EventEmitter<UserTask>

  private activeUserTasks: UserTask[] = []
  private oneSecondTimer;
  private timerSubscription$;

  constructor() {
    this.oneSecondTimer = timer(1000, 1000);
    this.timerSubscription$ = this.oneSecondTimer.subscribe(() => {
       this.checkForExpiredUserTasks();
    });
  }

  addNewTask(task: UserTask) {
    if(this.taskExists(task)) {
      this.completeTask(task);  // not included in example
    }
    else {
      task.startTime = new Date();
      this.activeUserTasks.push(task);
    }
  }

  private checkForExpiredUserTasks() {
    const currentTime = new Date();
    const expiredTasks: UserTask[] = [];

    this.activeUserTasks.forEach(userTask => {
       if (this.taskHasExpired(userTask.startTime, currentTime)) {
         expiredTasks.push(userTask);
       }
    });

    if (expiredTasks.length > 0) {
       this.handleExpiredTasks(expiredTasks);
    }
  }

  private taskHasExpired(taskStartTime: Date, currentTime: Date): boolean {
     return (currentTime.getTime() - taskStartTime.getTime()) / 1000 > 30;
  }

  private handleExpiredTasks(expiredTasks: UserTasks[]) {
     // remove task(s) from collection and then emit the task
  }
}

describe('User Action Tracking Service', () => {
   let service: UserTaskTrackerService;
   let testBed: TestBed;

   beforeEach(() => {
     TestBed.configureTestingModule({
         providers: [UserTaskTrackerService]
    });
   });

   beforeEach(() => {
     service = TestBed.get(UserTaskTrackerService);
   });

   it('should tick', fakeAsync(() => {
      const firstDate = new Date();
      tick(30000);
      const secondDate = new Date();
      expect(secondDate.getTime() - firstDate.getTime()).toBe(30000);
    }));

// Other tests removed for brevity

  it(`it should emit a UserTask when one expires`, fakeAsync(() => {
    let expiredUserTask: UserTask;

    service.TaskExpired.subscribe((userTask: UserTask) => {
      expiredUserTask = userTask;
    });

    service.addNewTask(new UserTask('abc', 'test action - request'));
    expect(service.getTaskCount()).toBe(1);

    tick(3100);

    expect(expiredUserTask).toBeDefined();
    expect(expiredUserTask.id).toBe('abc');
  }));
});