Checkout.php

<?php

namespace App\Domain;

class Checkout
{
    private $orderValidation;
    private $orderRepo;
    
    public function __construct(OrderValidation $orderValidation, OrderRepository $orderRepo)
    {
        $this->orderValidation = $orderValidation;
        $this->orderRepo = $orderRepo;
    }
    
    public function saveOrder(Order $order): Order
    {
        $this->orderValidation->validate($order);
        
        return $this->orderRepo->save($order);
    }
}