public function testCombine() {
$filter = $this
->getMock('Assetic\\Filter\\FilterInterface');
$this->fm
->expects($this
->once())
->method('get')
->with('bar')
->will($this
->returnValue($filter));
$xml = $this
->renderXml('combine.twig');
$this
->assertEquals(1, count($xml->asset));
$this
->assertEquals('css/packed.css', (string) $xml->asset[0]['url']);
}