AsseticBundle\FilterManager::get PHP Method

    public function get($alias)
    {
        if (parent::has($alias)) {
            return parent::get($alias);
        }
        $service = $this->serviceLocator;
        if (!$service->has($alias)) {
            throw new \InvalidArgumentException(sprintf('There is no "%s" filter in ZF2 service manager.', $alias));
        }
        $filter = $service->get($alias);
        if (!$filter instanceof FilterInterface) {
            $givenType = is_object($filter) ? get_class($filter) : gettype($filter);
            $message = 'Retrieved filter "%s" is not instanceof "Assetic\\Filter\\FilterInterface", but type was given %s';
            $message = sprintf($message, $alias, $givenType);
            throw new \InvalidArgumentException($message);
        }
        $this->set($alias, $filter);
        return $filter;
    }

 /**
  * @dataProvider getAliasGetValidProvider
  */
 public function testGetValid($alias, $object)
 {
     $this->assertInstanceOf('Assetic\\Filter\\FilterInterface', $object);
     $this->service->setService($alias, $object);
     $result = $this->object->get($alias);
     $this->assertInstanceOf('Assetic\\Filter\\FilterInterface', $result);
     $this->assertSame($result, $object);
 }