diff --git a/src/Service/CalculationService.php b/src/Service/CalculationService.php
index c673f3b8..75d5d064 100644
--- a/src/Service/CalculationService.php
+++ b/src/Service/CalculationService.php
@@ -43,7 +43,7 @@
  *     user_margin: float,
  *     groups: ServiceGroupType[]}
  */
-final class CalculationService implements ServiceSubscriberInterface
+class CalculationService implements ServiceSubscriberInterface
 {
     use MathTrait;
     use ServiceMethodsSubscriberTrait;
diff --git a/tests/DatabaseTrait.php b/tests/DatabaseTrait.php
index fd8f7431..98d8c290 100644
--- a/tests/DatabaseTrait.php
+++ b/tests/DatabaseTrait.php
@@ -85,12 +85,10 @@ protected function deleteEntity(?EntityInterface $entity): null
      */
     protected function getManager(): EntityManager
     {
-        /** @var ManagerRegistry $registry */
+        /** @psalm-var ManagerRegistry $registry */
         $registry = static::getContainer()->get('doctrine');
 
-        /** @var EntityManager $manager */
-        $manager = $registry->getManager();
-
-        return $manager;
+        /** @psalm-var EntityManager */
+        return $registry->getManager();
     }
 }
diff --git a/tests/Generator/CalculationGeneratorTest.php b/tests/Generator/CalculationGeneratorTest.php
new file mode 100644
index 00000000..87472573
--- /dev/null
+++ b/tests/Generator/CalculationGeneratorTest.php
@@ -0,0 +1,99 @@
+<?php
+/*
+ * This file is part of the Calculation package.
+ *
+ * (c) bibi.nu <bibi@bibi.nu>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace App\Tests\Generator;
+
+use App\Entity\CalculationState;
+use App\Generator\AbstractEntityGenerator;
+use App\Generator\CalculationGenerator;
+use App\Service\CalculationService;
+use App\Tests\EntityTrait\CalculationStateTrait;
+use App\Tests\EntityTrait\ProductTrait;
+use Doctrine\ORM\Exception\ORMException;
+use PHPUnit\Framework\Attributes\CoversClass;
+
+/**
+ * @extends GeneratorTestCase<CalculationGenerator>
+ */
+#[CoversClass(AbstractEntityGenerator::class)]
+#[CoversClass(CalculationGenerator::class)]
+class CalculationGeneratorTest extends GeneratorTestCase
+{
+    use CalculationStateTrait;
+    use ProductTrait;
+
+    private CalculationService $service;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->service = $this->getService(CalculationService::class);
+        $this->service->setTranslator($this->translator);
+    }
+
+    public function testNegativeCount(): void
+    {
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(-1, true);
+        self::assertValidateResults($actual, false, 0);
+    }
+
+    /**
+     * @throws ORMException
+     */
+    public function testNotSimulate(): void
+    {
+        $this->getCalculationState();
+        $product = $this->getProduct();
+        $product->setPrice(0.0);
+        $this->manager->flush();
+
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(1, false);
+        self::assertValidateResults($actual, true, 1);
+    }
+
+    /**
+     * @throws ORMException
+     */
+    public function testNotSimulateError(): void
+    {
+        $this->deleteCalculationState();
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(1, false);
+        self::assertValidateResults($actual, false, 0);
+    }
+
+    public function testOne(): void
+    {
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(1, true);
+        self::assertValidateResults($actual, true, 1);
+    }
+
+    protected function createGenerator(): CalculationGenerator
+    {
+        $generator = new CalculationGenerator($this->manager, $this->fakerService, $this->service);
+
+        return $this->updateGenerator($generator);
+    }
+
+    private function deleteCalculationState(): void
+    {
+        $repository = $this->manager->getRepository(CalculationState::class);
+        $entities = $repository->findAll();
+        foreach ($entities as $entity) {
+            $repository->remove($entity);
+        }
+        $this->manager->flush();
+    }
+}
diff --git a/tests/Generator/CustomerGeneratorTest.php b/tests/Generator/CustomerGeneratorTest.php
new file mode 100644
index 00000000..94b1e47f
--- /dev/null
+++ b/tests/Generator/CustomerGeneratorTest.php
@@ -0,0 +1,53 @@
+<?php
+/*
+ * This file is part of the Calculation package.
+ *
+ * (c) bibi.nu <bibi@bibi.nu>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace App\Tests\Generator;
+
+use App\Generator\AbstractEntityGenerator;
+use App\Generator\CustomerGenerator;
+use PHPUnit\Framework\Attributes\CoversClass;
+
+/**
+ * @extends GeneratorTestCase<CustomerGenerator>
+ */
+#[CoversClass(AbstractEntityGenerator::class)]
+#[CoversClass(CustomerGenerator::class)]
+class CustomerGeneratorTest extends GeneratorTestCase
+{
+    public function testNegativeCount(): void
+    {
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(-1, true);
+        self::assertValidateResults($actual, false, 0);
+    }
+
+    public function testNotSimulate(): void
+    {
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(1, false);
+        self::assertValidateResults($actual, true, 1);
+    }
+
+    public function testOne(): void
+    {
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(1, true);
+        self::assertValidateResults($actual, true, 1);
+    }
+
+    protected function createGenerator(): CustomerGenerator
+    {
+        $generator = new CustomerGenerator($this->manager, $this->fakerService);
+
+        return $this->updateGenerator($generator);
+    }
+}
diff --git a/tests/Generator/GeneratorTestCase.php b/tests/Generator/GeneratorTestCase.php
new file mode 100644
index 00000000..e04b75d8
--- /dev/null
+++ b/tests/Generator/GeneratorTestCase.php
@@ -0,0 +1,84 @@
+<?php
+/*
+ * This file is part of the Calculation package.
+ *
+ * (c) bibi.nu <bibi@bibi.nu>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace App\Tests\Generator;
+
+use App\Generator\AbstractEntityGenerator;
+use App\Service\FakerService;
+use App\Tests\DatabaseTrait;
+use App\Tests\KernelServiceTestCase;
+use App\Utils\StringUtils;
+use Doctrine\ORM\EntityManagerInterface;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\HttpFoundation\JsonResponse;
+use Symfony\Contracts\Translation\TranslatorInterface;
+
+/**
+ * @template TGenerator of AbstractEntityGenerator
+ */
+abstract class GeneratorTestCase extends KernelServiceTestCase
+{
+    use DatabaseTrait;
+
+    protected FakerService $fakerService;
+    protected LoggerInterface $logger;
+    protected EntityManagerInterface $manager;
+    protected TranslatorInterface $translator;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->logger = $this->createMock(LoggerInterface::class);
+        $this->translator = $this->createMock(TranslatorInterface::class);
+        $this->manager = $this->getService(EntityManagerInterface::class);
+        $this->fakerService = $this->getService(FakerService::class);
+    }
+
+    protected static function assertValidateResults(JsonResponse $actual, bool $expected, int $count): array
+    {
+        $content = $actual->getContent();
+        self::assertIsString($content);
+
+        $actual = StringUtils::decodeJson($content);
+        self::assertArrayHasKey('result', $actual);
+        self::assertSame($expected, $actual['result']);
+        if ($count <= 0) {
+            return $actual;
+        }
+
+        self::assertArrayHasKey('count', $actual);
+        self::assertSame($count, $actual['count']);
+        self::assertArrayHasKey('items', $actual);
+        self::assertIsArray($actual['items']);
+        self::assertCount($count, $actual['items']);
+
+        return $actual;
+    }
+
+    /**
+     * @psalm-return TGenerator
+     */
+    abstract protected function createGenerator(): AbstractEntityGenerator;
+
+    /**
+     * @psalm-param TGenerator $generator
+     *
+     * @psalm-return TGenerator
+     */
+    protected function updateGenerator(AbstractEntityGenerator $generator): AbstractEntityGenerator
+    {
+        $generator->setTranslator($this->translator);
+        $generator->setLogger($this->logger);
+
+        return $generator;
+    }
+}
diff --git a/tests/Generator/ProductGeneratorTest.php b/tests/Generator/ProductGeneratorTest.php
new file mode 100644
index 00000000..5cb3e1b4
--- /dev/null
+++ b/tests/Generator/ProductGeneratorTest.php
@@ -0,0 +1,61 @@
+<?php
+/*
+ * This file is part of the Calculation package.
+ *
+ * (c) bibi.nu <bibi@bibi.nu>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace App\Tests\Generator;
+
+use App\Generator\AbstractEntityGenerator;
+use App\Generator\ProductGenerator;
+use App\Tests\EntityTrait\CategoryTrait;
+use Doctrine\ORM\Exception\ORMException;
+use PHPUnit\Framework\Attributes\CoversClass;
+
+/**
+ * @extends GeneratorTestCase<ProductGenerator>
+ */
+#[CoversClass(AbstractEntityGenerator::class)]
+#[CoversClass(ProductGenerator::class)]
+class ProductGeneratorTest extends GeneratorTestCase
+{
+    use CategoryTrait;
+
+    public function testNegativeCount(): void
+    {
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(-1, true);
+        self::assertValidateResults($actual, false, 0);
+    }
+
+    /**
+     * @throws ORMException
+     */
+    public function testNotSimulate(): void
+    {
+        $this->getCategory();
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(1, false);
+        self::assertValidateResults($actual, true, 1);
+    }
+
+    public function testOne(): void
+    {
+        $generator = $this->createGenerator();
+        $actual = $generator->generate(1, true);
+        self::assertValidateResults($actual, true, 1);
+    }
+
+    protected function createGenerator(): ProductGenerator
+    {
+        $generator = new ProductGenerator($this->manager, $this->fakerService);
+
+        return $this->updateGenerator($generator);
+    }
+}