title: Unit test React functional component's function
body: <p>is there anyway we can unit test a function in a react Functional component. Since <code>wrapper.instance()</code> will return null for functional components what's the best way to include this function in test to get maximum coverage.</p>
  <pre><code>
  const SimpleFC: React.FC = () =&gt; {
  
      const callbackFunction = () =&gt; {
          // Do Stuffs
      }
  
      return (
          &lt;ChildComponent callback={callbackFunction} /&gt;
      )
  }
  
  export { SimpleFC };
  </code></pre>
  <p>In this code segment how can we invoke the <code>callbackFunction</code> ?</p>
  <p>Thanks in advance</p>