public function testReference() {
$asset = $this
->getMock('Assetic\\Asset\\AssetInterface');
$this->am
->expects($this
->any())
->method('get')
->with('foo')
->will($this
->returnValue($asset));
$xml = $this
->renderXml('reference.twig');
$this
->assertEquals(1, count($xml->asset));
$this
->assertStringStartsWith('css/', (string) $xml->asset['url']);
}