chai expect function to throw code example

Example 1: mocha should throw error

describe('createMap', () => {
    it('should throw an error if no contents were sent as argument', () => {
      expect(() => createMap()).to.throw('You have to send a list of things to map.');
    });
  });

Example 2: chai expect to be type array

expect([1, 2]).to.be.an('array');