title: Mock axios with axios-mock-adapter get undefined resp
body: <p>I created an axios instance ...</p>
  
  <pre><code>// api/index.js
  
  const api = axios.create({
    baseURL: '/api/',
    timeout: 2500,
    headers: { Accept: 'application/json' },
  });
  export default api;
  </code></pre>
  
  <p>And severals modules use it ..</p>
  
  <pre><code>// api/versions.js
  
  import api from './api';
  
  export function getVersions() {
    return api.get('/versions');
  }
  </code></pre>
  
  <p>I try to test like ..</p>
  
  <pre><code>// Test
  import { getVersions } from './api/versions';
  
  const versions= [{ id: 1, desc: 'v1' }, { id: 2, desc: 'v2' }];
  mockAdapter.onGet('/versions').reply(200, versions);
  
  getVersions.then((resp) =&gt; { // resp is UNDEFINED?
    expect(resp.data).toEqual(versions);
    done();
  });
  </code></pre>
  
  <p>Why resp is undefined?</p>