title: simulate for onClick not working in enzyme
body: <p>This is a cancel button</p>
  
  <pre><code>&lt;div className="cancelFileBtn" onClick={this.props.cancelFileSending}&gt;
  </code></pre>
  
  <p>I need to simulate its click,I tried the following test </p>
  
  <pre><code>wrapper.find('.cancelFileBtn').simulate('click');
  </code></pre>
  
  <p>But the click function is still undefined...Did I miss anything else? 
  and it will be very helpful if anyone can mention any changes if exist in simulating</p>
  
  <pre><code>&lt;SendMessageButton onClick={this.props.handleClickSendMessage} loadingFile={this.props.loadingFile}/&gt;
  </code></pre>