title: Jest not finding className
body: <p>I am struggling to determine why my jest test can never find my components classes/
  This is the component output from a debug statement</p>
  
  <pre><code>  &lt;FileLine file={{...}} readOnly={false} onSelectedRevisionChanged={[Function: mockConstructor]}&gt;
    &lt;tr className="warning"&gt;
      &lt;td className="col-xs-2"&gt;
        Data
      &lt;/td&gt;
      &lt;td className="col-xs-2"&gt;
        &lt;select className="revision-selection form-control" value="1" onChange={[Function: value]}&gt;
          &lt;option value="1"&gt;
            1
          &lt;/option&gt;
          &lt;option value="2"&gt;
            2
          &lt;/option&gt;
        &lt;/select&gt;
      &lt;/td&gt;
      &lt;td className="col-xs-2"&gt;
        Loading...
      &lt;/td&gt;
  </code></pre>
  
  <p></p>
  
  <p>My jest test is checking for the following</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>it.only('sends selected revision when changed', () =&gt; {  
    const selectionCallBack = jest.fn();
    const component = mount(&lt;FileLine file={fileUnderTest} readOnly={false} onSelectedRevisionChanged={selectionCallBack} /&gt;);
  
    //This will change the drop down to a different value
    const revisionSelection = component.find('revision-selection');
    console.log(component.debug());
    expect(revisionSelection.length).to.equal(1);
  
    revisionSelection.simulate('change', { target: { value: '2' } });
  
    expect(selectionCallBack).toBeCalledWith('packageRoot/F5___/Apps/GM/GM.E86_r2');
   });</code></pre>
  </div>
  </div>
  </p>
  
  <p>The expect statement is always indicating that revisionSelection is always undefined. Pretty confused how that is possible given it is showing that class in the output.</p>