chore: fix phpstan errors

tests/Form/DataTransformer/RoomSelectionToIdTransformerTest.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Form\DataTransformer;
+
+use App\Form\DataTransformer\RoomSelectionToIdTransformer;
+use App\Form\Model\RoomSelectionDto;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Form\Exception\TransformationFailedException;
+
+class RoomSelectionToIdTransformerTest extends TestCase
+{
+    public function testReverseTransformAcceptsIntegerAndNumericStringIds(): void
+    {
+        $transformer = new RoomSelectionToIdTransformer([]);
+
+        self::assertSame(12, $transformer->reverseTransform(12));
+        self::assertSame(12, $transformer->reverseTransform('12'));
+    }
+
+    public function testReverseTransformReturnsNullForEmptyValues(): void
+    {
+        $transformer = new RoomSelectionToIdTransformer([]);
+
+        self::assertNull($transformer->reverseTransform(null));
+        self::assertNull($transformer->reverseTransform(''));
+    }
+
+    public function testReverseTransformRejectsInvalidValues(): void
+    {
+        $transformer = new RoomSelectionToIdTransformer([]);
+
+        $this->expectException(TransformationFailedException::class);
+
+        $transformer->reverseTransform('1.5');
+    }
+
+    public function testTransformReturnsMatchingRoomSelectionDto(): void
+    {
+        $roomSelection = new RoomSelectionDto();
+        $roomSelection->id = 7;
+        $roomSelection->label = 'Doppelzimmer';
+
+        $transformer = new RoomSelectionToIdTransformer([$roomSelection]);
+
+        self::assertSame($roomSelection, $transformer->transform(7));
+    }
+}