public function testRenderParentBlockOptimizer() {
$env = new Twig_Environment(new Twig_Loader_String(), array(
'cache' => false,
'autoescape' => false,
));
$stream = $env
->parse($env
->tokenize('{% extends "foo" %}{% block content %}{{ parent() }}{% endblock %}', 'index'));
$node = $stream
->getNode('blocks')
->getNode('content')
->getNode(0)
->getNode('body');
$this
->assertEquals('Twig_Node_Expression_Parent', get_class($node));
$this
->assertTrue($node
->getAttribute('output'));
}