public function testTtl(EntityManager $em)
{
$article = new Article();
$article->setId(499)->setTitle('Cached Article');
$em->persist($article, 2)->flush();
$r_article = $em->retrieve(Article::class, '499', false);
$this->assertEquals('Cached Article', $r_article->getTitle());
sleep(3);
$this->setExpectedException(NotFoundException::class);
$em->retrieve(Article::class, '499', false);
}