public function testOneToMany(EntityManager $em)
{
$time = new \DateTime();
$article1 = new Article();
$article1->setId(101)->setTitle('Article 101')->setTimeCreated($time)->setLastModified($time);
$article2 = new Article();
$article2->setId(102)->setTitle('Article 102')->setTimeCreated($time)->setLastModified($time);
$category1 = new Category();
$category1->setId(101)->setName('Category 101');
$category1->addArticle($article1)->addArticle($article2);
$em->persist($category1)->persist($article1)->persist($article2)->flush();
}