public function testUlAttr()
{
$nestable = new \Nestable\Services\NestableService();
$nested = $nestable->make($this->categories);
$html = $nested->ulAttr(['class' => 'nav-bar'])->renderAsHtml();
$this->assertRegExp('/' . $this->_get_pattern('attribute_pattern_for_ul') . '/', $html);
}