public function testSnippetsWithCallback()
{
$this->markTestIncomplete('Update required');
$app = $this->getApp();
$app['extensions']->register(new Mock\SnippetCallbackExtension($app));
// Test snippet inserts at top of <head>
$html = $app['extensions']->processSnippetQueue($this->template);
$this->assertEquals($this->html($this->expectedStartOfHead), $this->html($html));
}