title: expect is not defined in supertest-as-promised
body: <p>When I used bellow code the error shown <strong>expect is not defined</strong> (inside of then )</p>
  
  <p>Documentation <a href="https://github.com/WhoopInc/supertest-as-promised#debugging" rel="nofollow">link</a></p>
  
  <pre><code>it("should return error", function () {
    return request(app).get("/verify")
      .expect(200)
      .then(function (res) {
        return expect(res.body.error[0].message).to.equal("NEW_CODE_REQUIRED");
      });
  });
  </code></pre>
  
  <p>how can I check this?</p>