如果字符串包含五个@，如何通过chai进行检查？

const chai = require('chai');
const expect = chai.expect;

describe('String Check', () => {
  it('should contain five @ symbols', () => {
    const str = 'example@string@with@five@at@symbols';
    const regex = /@/g;
    const count = (str.match(regex) || []).length;
    expect(count).to.equal(5);
  });
});