UlidGenerator example

use Doctrine\ORM\Mapping\Entity;
use PHPUnit\Framework\TestCase;
use Symfony\Bridge\Doctrine\IdGenerator\UlidGenerator;
use Symfony\Component\Uid\Factory\UlidFactory;
use Symfony\Component\Uid\Ulid;

class UlidGeneratorTest extends TestCase
{
    public function testUlidCanBeGenerated()
    {
        $em = (new \ReflectionClass(EntityManager::class))->newInstanceWithoutConstructor();
        $generator = new UlidGenerator();
        $ulid = $generator->generate($em, new Entity());

        $this->assertInstanceOf(Ulid::class, $ulid);
        $this->assertTrue(Ulid::isValid($ulid));
    }

    public function testUlidFactory()
    {
        $ulid = new Ulid('00000000000000000000000000');
        $em = (new \ReflectionClass(EntityManager::class))->newInstanceWithoutConstructor();
        $factory = $this->createMock(UlidFactory::class);