/**
  * Check the generated HTML for well-formedness.
  */
 public function testGetCaptchaHtml()
 {
     //we cannot test getCaptchaHtml() alone because
     // verifyCaptcha() is not called yet at that place.
     // Using __toString() before is needed to generate
     // the captcha question and answer itself.
     (string) $this->nc;
     $str = $this->nc->getCaptchaHtml();
     $xml = '<?xml version="1.0" encoding="utf-8"?>' . "\n<test>\n" . $str . "\n</test>";
     //this is a cheap way to see if the xml is well-formed
     $this->assertTag(array('test'), $xml, '', false);
 }