/**
  * test atrybutów
  */
 public function attrTest()
 {
     $el = new HtmlElement('link');
     $el->attr('test', 'ok');
     $this->assertEquals('ok', $el->attr('test'));
     $el->removeAttr('test');
     $this->assertEquals('', $el->attr('test'));
     $el->destroy($el);
 }