public function testServeIconSends404ForNonExistentGuid()
{
$path_key = \Elgg\Application::GET_PATH_KEY;
$this->request = \Elgg\Http\Request::create("?{$path_key}=serve-icon/55/small");
$service = $this->createService();
$service->setCurrentTime();
$response = $service->handleServeIconRequest(false);
$this->assertEquals(404, $response->getStatusCode());
$this->assertEquals($service->getCurrentTime('-1 day'), $response->getExpires());
}