UuidGenerator example

use Symfony\Bridge\Doctrine\IdGenerator\UuidGenerator;
use Symfony\Component\Uid\Factory\UuidFactory;
use Symfony\Component\Uid\Uuid;
use Symfony\Component\Uid\UuidV4;
use Symfony\Component\Uid\UuidV6;

class UuidGeneratorTest extends TestCase
{
    public function testUuidCanBeGenerated()
    {
        $em = (new \ReflectionClass(EntityManager::class))->newInstanceWithoutConstructor();
        $generator = new UuidGenerator();
        $uuid = $generator->generate($em, new Entity());

        $this->assertInstanceOf(Uuid::class, $uuid);
    }

    public function testCustomUuidfactory()
    {
        $uuid = new UuidV4();
        $em = (new \ReflectionClass(EntityManager::class))->newInstanceWithoutConstructor();
        $factory = $this->createMock(UuidFactory::class);
        $factory->expects($this->any())