dsa.js/src/data-structures/queues/queue.spec.js

Data Structures & Algorithms in JS

const { Queue } = require('../../index');

describe('Queue', () => {
  let queue;

  beforeEach(() => {
    queue = new Queue();
  });

  describe('#add', () => {
    it('should push an element to the queue', () => {
      expect(queue.size).toEqual(0);
      queue.add(1);
      expect(queue.size).toEqual(1);
    });
  });

  describe('#remove', () => {
    beforeEach(() => {
      queue.add('a');
      queue.add('b');
    });

    it('should get last element entered', () => {
      expect(queue.remove()).toEqual('a');
      expect(queue.remove()).toEqual('b');
    });

    it('should keep the order after some addition', () => {
      expect(queue.remove()).toEqual('a');
      queue.add('c');
      expect(queue.remove()).toEqual('b');
      expect(queue.remove()).toEqual('c');
      expect(queue.remove()).toBe(null);
    });
  });

  describe('#isEmpty', () => {
    it('should return true when empty', () => {
      expect(queue.isEmpty()).toBe(true);
    });

    it('should return false when not empty', () => {
      queue.add('a');
      // expect(queue.size).toBe(1);
      expect(queue.isEmpty()).toBe(false);
    });
  });

  describe('#back', () => {
    it('should return null if empty', () => {
      expect(queue.back()).toEqual(null);
    });

    it('should return newest element', () => {
      queue.enqueue('oldest');
      queue.enqueue('newest');
      expect(queue.back()).toEqual('newest');
    });
  });

  describe('#front', () => {
    it('should return null if empty', () => {
      expect(queue.front()).toEqual(null);
    });

    it('should return oldest element', () => {
      queue.enqueue('oldest');
      queue.enqueue('newest');
      expect(queue.front()).toEqual('oldest');
    });
  });
});