text: import Queue from './queue';
  
  describe('Queue', () => {
    const queue = new Queue();
  
    it('should init a empty queue', () => {
      expect(queue.isEmpty()).toBeTruthy();
    });
  
    it('should add 1 in queue', () => {
      queue.add(1);
      expect(queue.isEmpty()).toBeFalsy();
      expect(queue.peek()).toBe(1);
    });
  
    it('should push 2 in queue, peek should return 1', () => {
      queue.add(2);
      expect(queue.peek()).toBe(1);
    });
  
    it('should remove 1', () => {
      expect(queue.remove()).toBe(1);
    });
  
    it('should remove 2, and queue is empty', () => {
      expect(queue.remove()).toBe(2);
      expect(queue.isEmpty()).toBeTruthy();
    });
  });
  