diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index f0b89d9..8f17675 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -46,13 +46,36 @@ jobs:
       - name: Run PHPStan
         run: composer phpstan
 
-  phpunit:
+  phpunit-unit:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - uses: ./.github/actions/setup-php
       - name: Run PHPUnit
-        run: composer phpunit -- --coverage-clover=coverage.xml
+        run: composer phpunit:unit -- --coverage-clover=coverage.xml
+      - name: Codecov
+        uses: codecov/codecov-action@v4
+        with:
+          files: ./coverage.xml
+
+  phpunit-integration:
+    runs-on: ubuntu-latest
+    services:
+      mariadb:
+        image: mariadb:10.5
+        env:
+          MARIADB_ROOT_PASSWORD: swagbraintree
+          MYSQL_DATABASE: swagbraintree_test
+        ports: ['3306:3306']
+    env:
+      DATABASE_URL: mysql://root:swagbraintree@127.0.0.1:3306/swagbraintree
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./.github/actions/setup-php
+      - name: Setup database
+        run: composer setup:test
+      - name: Run PHPUnit
+        run: composer phpunit:integration -- --coverage-clover=coverage.xml
       - name: Codecov
         uses: codecov/codecov-action@v4
         with:
@@ -60,9 +83,20 @@ jobs:
 
   infection:
     runs-on: ubuntu-latest
+    services:
+      mariadb:
+        image: mariadb:10.5
+        env:
+          MARIADB_ROOT_PASSWORD: swagbraintree
+          MYSQL_DATABASE: swagbraintree_test
+        ports: ['3306:3306']
+    env:
+      DATABASE_URL: mysql://root:swagbraintree@127.0.0.1:3306/swagbraintree
     steps:
       - uses: actions/checkout@v4
       - uses: ./.github/actions/setup-php
+      - name: Setup database
+        run: composer setup:test
       - name: Run Infection
         run: composer infection -- --min-msi=95
         env:
diff --git a/composer.json b/composer.json
index ed6e86f..cd2687f 100644
--- a/composer.json
+++ b/composer.json
@@ -80,12 +80,19 @@
         "setup": [
             "bin/console doctrine:schema:drop --force --full-database",
             "bin/console doctrine:migrations:migrate -n",
-            "@setup:url"
+            "@setup:url",
+            "@setup:test"
         ],
         "setup:url": [
             "bin/console setup:url",
             "npm run dev"
-        ]
+        ],
+        "setup:test": [
+            "bin/console doctrine:schema:drop --env=test --force --full-database",
+            "bin/console doctrine:migrations:migrate --env=test -n"
+        ],
+        "phpunit:unit": "@phpunit --testsuite=SwagBraintreeUnitTest",
+        "phpunit:integration": "@phpunit --testsuite=SwagBraintreeIntegrationTest"
     },
     "conflict": {
         "symfony/symfony": "*"
diff --git a/devenv.nix b/devenv.nix
index 5896094..e095de6 100644
--- a/devenv.nix
+++ b/devenv.nix
@@ -87,7 +87,10 @@ in {
   services.mysql = {
     enable = true;
     package = pkgs.mariadb_105;
-    initialDatabases = lib.mkDefault [{ name = "swagbraintree"; }];
+    initialDatabases = lib.mkDefault [
+      { name = "swagbraintree"; }
+      { name = "swagbraintree_test"; }
+    ];
     ensureUsers = lib.mkDefault [
       {
         name = "swagbraintree";
diff --git a/phpstan.neon b/phpstan.neon
index 208d861..a23b7d6 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -28,6 +28,10 @@ parameters:
                 message: '#Multiple class/interface/trait is not allowed in single file#'
                 path: tests/unit
 
+            - # don't want to prefix this
+                message: '#Only abstract classes can be extended#'
+                path: tests/integration/DoctrineUuidTest.php
+
 rules:
     # rules from https://github.com/symplify/phpstan-rules
     # domain
diff --git a/src/Doctrine/RespectfulUuidGenerator.php b/src/Doctrine/RespectfulUuidGenerator.php
deleted file mode 100644
index 38b3476..0000000
--- a/src/Doctrine/RespectfulUuidGenerator.php
+++ /dev/null
@@ -1,30 +0,0 @@
-<?php declare(strict_types=1);
-
-namespace Swag\Braintree\Doctrine;
-
-use Doctrine\ORM\EntityManagerInterface;
-use Doctrine\ORM\Id\AbstractIdGenerator;
-use Swag\Braintree\Entity\Contract\EntityInterface;
-use Symfony\Component\Uid\Uuid;
-
-class RespectfulUuidGenerator extends AbstractIdGenerator
-{
-    public function generateId(EntityManagerInterface $em, mixed $entity): ?Uuid
-    {
-        if (!$entity) {
-            return null;
-        }
-
-        if (!$entity instanceof EntityInterface) {
-            throw new \RuntimeException(
-                \sprintf(
-                    'Class %s not supported for respectful uuid generation. Use %s instead',
-                    $entity::class,
-                    EntityInterface::class
-                )
-            );
-        }
-
-        return $entity->getId() ?? Uuid::v7();
-    }
-}
diff --git a/src/Entity/Contract/EntityIdTrait.php b/src/Entity/Contract/EntityIdTrait.php
index 4d4cd1c..659ff0e 100644
--- a/src/Entity/Contract/EntityIdTrait.php
+++ b/src/Entity/Contract/EntityIdTrait.php
@@ -3,7 +3,6 @@
 namespace Swag\Braintree\Entity\Contract;
 
 use Doctrine\ORM\Mapping as ORM;
-use Swag\Braintree\Doctrine\RespectfulUuidGenerator;
 use Symfony\Component\Uid\Uuid;
 
 #[ORM\MappedSuperclass]
@@ -12,17 +11,17 @@ trait EntityIdTrait
     #[ORM\Id]
     #[ORM\Column(type: 'uuid', unique: true)]
     #[ORM\GeneratedValue(strategy: 'CUSTOM')]
-    #[ORM\CustomIdGenerator(class: RespectfulUuidGenerator::class)]
+    #[ORM\CustomIdGenerator(class: 'doctrine.uuid_generator')]
     // will never be null in the database
     // null only signalizes the uuid-generator to generate a new uuid for the database
-    private ?Uuid $id = null;
+    private Uuid $id;
 
     public function getId(): ?Uuid
     {
-        return $this->id;
+        return $this->id ?? null;
     }
 
-    public function setId(?Uuid $id): self
+    public function setId(Uuid $id): self
     {
         $this->id = $id;
 
diff --git a/src/Entity/Contract/EntityInterface.php b/src/Entity/Contract/EntityInterface.php
index 5a9f9a0..472c785 100644
--- a/src/Entity/Contract/EntityInterface.php
+++ b/src/Entity/Contract/EntityInterface.php
@@ -8,7 +8,7 @@ interface EntityInterface
 {
     public function getId(): ?Uuid;
 
-    public function setId(?Uuid $id): self;
+    public function setId(Uuid $id): self;
 
     public function getCreatedAt(): \DateTimeInterface;
 
diff --git a/tests/integration/DoctrineUuidTest.php b/tests/integration/DoctrineUuidTest.php
new file mode 100644
index 0000000..20b8daf
--- /dev/null
+++ b/tests/integration/DoctrineUuidTest.php
@@ -0,0 +1,54 @@
+<?php declare(strict_types=1);
+
+namespace Swag\Braintree\Tests\Integration;
+
+use Swag\Braintree\Entity\ConfigEntity;
+
+class DoctrineUuidTest extends SwagBraintreeTestCase
+{
+    public function testPersistTwice(): void
+    {
+        $em = $this->getEntityManager();
+
+        $shop = $this->createShop();
+        $config = (new ConfigEntity())
+            ->setShop($shop);
+
+        $em->persist($config);
+        $em->flush();
+
+        static::assertNotNull($config->getId());
+        $id = (string) $config->getId();
+
+        $em->persist($config);
+        $em->flush();
+
+        static::assertSame($id, (string) $config->getId());
+    }
+
+    public function testWithRef(): void
+    {
+        $em = $this->getEntityManager();
+
+        $shop = $this->createShop();
+        $config = (new ConfigEntity())
+            ->setShop($shop);
+
+        $em->persist($config);
+        $em->flush();
+
+        static::assertNotNull($config->getId());
+        $id = (string) $config->getId();
+
+        $configRef = $em->getReference(ConfigEntity::class, $id);
+        $configRef->setThreeDSecureEnforced(true);
+
+        $em->persist($configRef);
+        $em->flush();
+
+        $config = $em->find(ConfigEntity::class, $id);
+
+        static::assertSame($id, (string) $config->getId());
+        static::assertTrue($config->isThreeDSecureEnforced());
+    }
+}
diff --git a/tests/integration/SwagBraintreeTestCase.php b/tests/integration/SwagBraintreeTestCase.php
new file mode 100644
index 0000000..2f7d1e4
--- /dev/null
+++ b/tests/integration/SwagBraintreeTestCase.php
@@ -0,0 +1,62 @@
+<?php declare(strict_types=1);
+
+namespace Swag\Braintree\Tests\Integration;
+
+use Doctrine\ORM\EntityManagerInterface;
+use Swag\Braintree\Entity\ShopEntity;
+use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+
+class SwagBraintreeTestCase extends KernelTestCase
+{
+    protected function tearDown(): void
+    {
+        $conn = static::getEntityManager()->getConnection();
+        $tables = $conn->createSchemaManager()->listTableNames();
+        /** @phpstan-ignore-next-line - yes `getTableName` will work */
+        $migrationTable = static::getContainer()->get('doctrine.migrations.dependency_factory')
+            ->getConfiguration()
+            ->getMetadataStorageConfiguration()
+            ->getTableName();
+
+        $conn->executeStatement('SET FOREIGN_KEY_CHECKS=0;');
+
+        try {
+            foreach ($tables as $table) {
+                if ($table === $migrationTable) {
+                    continue;
+                }
+
+                $conn->executeStatement(\sprintf(
+                    'TRUNCATE TABLE %s',
+                    $conn->quoteIdentifier($table),
+                ));
+            }
+        } finally {
+            $conn->executeStatement('SET FOREIGN_KEY_CHECKS=1;');
+        }
+
+        parent::tearDown();
+    }
+
+    protected static function getEntityManager(): EntityManagerInterface
+    {
+        return static::getContainer()->get('doctrine.orm.default_entity_manager');
+    }
+
+    protected static function createShop(string $url = 'https://shop.example.com', string $secret = 'definitly-a-secure-secret'): ShopEntity
+    {
+        $shopId = \bin2hex(\random_bytes(10));
+
+        $shop = new ShopEntity(
+            $shopId,
+            $url,
+            $secret,
+        );
+
+        $em = static::getEntityManager();
+        $em->persist($shop);
+        $em->flush();
+
+        return $shop;
+    }
+}
diff --git a/tests/unit/Doctrine/RespectfulUuidGeneratorTest.php b/tests/unit/Doctrine/RespectfulUuidGeneratorTest.php
deleted file mode 100644
index cd8852a..0000000
--- a/tests/unit/Doctrine/RespectfulUuidGeneratorTest.php
+++ /dev/null
@@ -1,99 +0,0 @@
-<?php declare(strict_types=1);
-
-namespace Swag\Braintree\Tests\Unit\Doctrine;
-
-use Doctrine\ORM\EntityManager;
-use PHPUnit\Framework\Attributes\CoversClass;
-use PHPUnit\Framework\TestCase;
-use Swag\Braintree\Doctrine\RespectfulUuidGenerator;
-use Swag\Braintree\Entity\Contract\EntityInterface;
-use Symfony\Component\Uid\Uuid;
-
-#[CoversClass(RespectfulUuidGenerator::class)]
-class RespectfulUuidGeneratorTest extends TestCase
-{
-    public function testGenerateId(): void
-    {
-        $entity = $this->getTestEntity();
-
-        $generator = new RespectfulUuidGenerator();
-        $id = $generator->generateId($this->createMock(EntityManager::class), $entity);
-
-        static::assertNotNull($id);
-        static::assertTrue(Uuid::isValid($id->toRfc4122()));
-    }
-
-    public function testGenerateIdWithNullEntity(): void
-    {
-        $generator = new RespectfulUuidGenerator();
-        $id = $generator->generateId($this->createMock(EntityManager::class), null);
-
-        static::assertNull($id);
-    }
-
-    public function testGenerateIdWithNonEntity(): void
-    {
-        $entity = new \stdClass();
-
-        $generator = new RespectfulUuidGenerator();
-
-        static::expectException(\RuntimeException::class);
-        static::expectExceptionMessage('Class stdClass not supported for respectful uuid generation. Use Swag\Braintree\Entity\Contract\EntityInterface instead');
-
-        $generator->generateId($this->createMock(EntityManager::class), $entity);
-    }
-
-    public function testGenerateIdWithExistingId(): void
-    {
-        $uuid = Uuid::v7();
-
-        $entity = $this->getTestEntity($uuid);
-
-        $generator = new RespectfulUuidGenerator();
-        $id = $generator->generateId($this->createMock(EntityManager::class), $entity);
-
-        static::assertNotNull($id);
-        static::assertSame($uuid, $id);
-    }
-
-    private function getTestEntity(?Uuid $id = null): EntityInterface
-    {
-        return new class($id) implements EntityInterface {
-            public function __construct(private ?Uuid $id = null)
-            {
-            }
-
-            public function getId(): ?Uuid
-            {
-                return $this->id;
-            }
-
-            public function setId(?Uuid $id): EntityInterface
-            {
-                $this->id = $id;
-
-                return $this;
-            }
-
-            public function getCreatedAt(): \DateTimeInterface
-            {
-                return new \DateTime();
-            }
-
-            public function setCreatedAt(\DateTimeInterface $createdAt): EntityInterface
-            {
-                return $this;
-            }
-
-            public function getUpdatedAt(): ?\DateTimeInterface
-            {
-                return null;
-            }
-
-            public function setUpdatedAt(?\DateTimeInterface $updatedAt): EntityInterface
-            {
-                return $this;
-            }
-        };
-    }
-}