如何在chai测试框架中测试数组？

npm install chai chai-as-promised --save-dev

const chai = require('chai');
const chaiAsPromised = require('chai-as-promised');

chai.use(chaiAsPromised);
const expect = chai.expect;

describe('Array', () => {
  it('should return the length of the array', () => {
    const arr = [1, 2, 3];
    expect(arr).to.have.lengthOf(3);
  });

  it('should include a specific value', () => {
    const arr = [1, 2, 3];
    expect(arr).to.include(2);
  });

  it('should be empty', () => {
    const arr = [];
    expect(arr).to.be.empty;
  });

  it('should be sorted in ascending order', () => {
    const arr = [1, 2, 3];
    expect(arr).to.be.ascending;
  });

  it('should be a subset of another array', () => {
    const arr1 = [1, 2, 3];
    const arr2 = [1, 2, 3, 4, 5];
    expect(arr1).to.be.subsetOf(arr2);
  });

  it('should be deeply equal to another array', () => {
    const arr1 = [1, 2, [3, 4]];
    const arr2 = [1, 2, [3, 4]];
    expect(arr1).to.deep.equal(arr2);
  });
});