title: Finding a TextSpan to tap on with Flutter tests
body: <p>With a Flutter WidgetTester how can you tap on a TextSpan, like in the code below?</p>
  
  <pre><code>RichText(
    text: TextSpan(
      children: [
        TextSpan(text: 'aaa '),
        TextSpan(
          text: 'bbb ',
          recognizer: TapGestureRecognizer()
            ..onTap = () { 
              // How to reach this code in a widget test?
            },
        ),
        TextSpan(text: 'ccc'),
      ],
    ),
  )
  </code></pre>