In order to run my tests headless, i used HTMLUnit but my tests fail and not able to find ID's
<p>Installed <code>Xvfb</code> using <code>pip install robotframework-xvfb</code>. Even after successful installation, on running tests i get below error</p>

<blockquote>
  <p>XVFB sample<br>
  | FAIL | EnvironmentError: Can not find Xvfb. Please install it and
  try again.</p>
</blockquote>