feat: extract room grouping from booking service

tests/Service/BookingRoomSelectionServiceTest.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Service;
+
+use App\BusProNet\Model\Room;
+use App\Service\BookingRoomSelectionService;
+use PHPUnit\Framework\TestCase;
+
+class BookingRoomSelectionServiceTest extends TestCase
+{
+    private BookingRoomSelectionService $service;
+
+    protected function setUp(): void
+    {
+        $this->service = new BookingRoomSelectionService();
+    }
+
+    public function testGroupRoomsBySelectionTypeSplitsAndSortsRooms(): void
+    {
+        $rooms = [
+            10 => $this->createRoom(10, '2 Bett Zimmer', 4),
+            11 => $this->createRoom(11, 'Suite', 2),
+            12 => $this->createRoom(12, '3 Bett Zimmer', 6),
+        ];
+
+        $groups = $this->service->groupRoomsBySelectionType($rooms);
+
+        $this->assertSame([10, 12], array_keys($groups[Room::SELECTION_TYPE_BY_PAX]));
+        $this->assertSame([11], array_keys($groups[Room::SELECTION_TYPE_BY_ROOM]));
+    }
+
+    private function createRoom(int $id, string $label, int $maxPax): Room
+    {
+        $room = new Room();
+        $room->id = $id;
+        $room->label = $label;
+        $room->maxPax = $maxPax;
+
+        return $room;
+    }
+}