text: const chai = require('chai');
  const expect = chai.expect;
  
  function testFunc (opt) {
    if (opt === undefined) {
      return Promise.reject(new Error());
    }
  }
  
  describe('testFunc', function () {
    it('return with a promise', function () {
      expect(testFunc()).to.be.a('promise');
    })
    describe('return with a promise that', function () {
      it('is rejected when no parameters are passed to it', async function () {
        try {
          const result = await testFunc();
        } catch (e) { return; }
        return Promise.reject(new Error('Should have thrown'))
      })
    });
  });
  