title: Enzyme cannot find child component in shallow test
body: <p>Is this not the correct way to render a react/reflux test with enzyme but without the store, ie, <a href="https://medium.com/netscape/testing-a-react-redux-app-using-jest-and-enzyme-b349324803a9#9d68" rel="noreferrer">"dumb"</a></p>
  
  <pre><code>import React from 'react'
  import { shallow, render } from 'enzyme'
  import { Controls } from '../Controls' // named export
  import LoadingSpinner from '../LoadingSpinner'
  let wrapper
  let loadingFlags = {
    controls: true
  }
  describe('&lt;Controls /&gt;', () =&gt; {
    it('should render only the loading spinner', () =&gt; {
      wrapper = shallow(&lt;Controls loadingFlags={loadingFlags} /&gt;) // this ensures the spinner will show until data is ready
      expect(wrapper.length).toEqual(1) // test passes
      expect(wrapper.find(LoadingSpinner)).to.have.length(1)
      // ^ TypeError: Cannot read property 'have' of undefined
    })
  })
  </code></pre>
  
  <p>When I log <code>wrapper.html()</code> I can see the <code>&lt;img class='spinner' /&gt;</code> is rendered, but enzyme cannot find it as a component. To me, the <a href="http://airbnb.io/enzyme/docs/api/shallow.html#shallow-rendering-api" rel="noreferrer">docs</a> indicate this is exactly what I should be doing. I suppose I could check for a child with that class, but that seems messier than checking for the component itself, eg the class changes within the Spinner component.</p>
  
  <h3>How can I test for the existence of this child component?</h3>