add iterface to refundUnits command

spec/Creator/RefundUnitsCommandCreatorSpec.php

@@ -16,6 +16,7 @@
 use PhpSpec\ObjectBehavior;
 use Sylius\RefundPlugin\Calculator\UnitRefundTotalCalculatorInterface;
 use Sylius\RefundPlugin\Command\RefundUnits;
+use Sylius\RefundPlugin\Command\RefundUnitsInterface;
 use Sylius\RefundPlugin\Creator\RefundUnitsCommandCreatorInterface;
 use Sylius\RefundPlugin\Model\OrderItemUnitRefund;
 use Sylius\RefundPlugin\Model\RefundType;
@@ -120,7 +121,7 @@ public function it_throws_exception_if_there_is_no_order_number_provided(Request
     public function getMatchers(): array
     {
         return [
-            'returnCommand' => function (RefundUnits $command, RefundUnits $expectedCommand): bool {
+            'returnCommand' => function (RefundUnitsInterface $command, RefundUnitsInterface $expectedCommand): bool {
                 return
                     $command->orderNumber() === $expectedCommand->orderNumber() &&
                     $command->units() == $expectedCommand->units() &&

src/Command/RefundUnits.php

@@ -17,7 +17,7 @@
 use Sylius\RefundPlugin\Model\ShipmentRefund;
 use Webmozart\Assert\Assert;
 
-class RefundUnits
+class RefundUnits implements RefundUnitsInterface
 {
     /** @var string */
     private $orderNumber;

src/Command/RefundUnitsInterface.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of the Sylius package.
+ *
+ * (c) Paweł Jędrzejewski
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Sylius\RefundPlugin\Command;
+
+use Sylius\RefundPlugin\Model\OrderItemUnitRefund;
+use Sylius\RefundPlugin\Model\ShipmentRefund;
+
+interface RefundUnitsInterface
+{
+    public function orderNumber(): string;
+
+    /** @return array|OrderItemUnitRefund[] */
+    public function units(): array;
+
+    /** @return array|ShipmentRefund[] */
+    public function shipments(): array;
+
+    public function paymentMethodId(): int;
+
+    public function comment(): string;
+}

src/Creator/RefundUnitsCommandCreator.php

@@ -15,6 +15,7 @@
 
 use Sylius\RefundPlugin\Calculator\UnitRefundTotalCalculatorInterface;
 use Sylius\RefundPlugin\Command\RefundUnits;
+use Sylius\RefundPlugin\Command\RefundUnitsInterface;
 use Sylius\RefundPlugin\Exception\InvalidRefundAmount;
 use Sylius\RefundPlugin\Model\OrderItemUnitRefund;
 use Sylius\RefundPlugin\Model\RefundType;
@@ -33,7 +34,7 @@ public function __construct(UnitRefundTotalCalculatorInterface $unitRefundTotalC
         $this->unitRefundTotalCalculator = $unitRefundTotalCalculator;
     }
 
-    public function fromRequest(Request $request): RefundUnits
+    public function fromRequest(Request $request): RefundUnitsInterface
     {
         Assert::true($request->attributes->has('orderNumber'), 'Refunded order number not provided');
 

src/Creator/RefundUnitsCommandCreatorInterface.php

@@ -13,10 +13,10 @@
 
 namespace Sylius\RefundPlugin\Creator;
 
-use Sylius\RefundPlugin\Command\RefundUnits;
+use Sylius\RefundPlugin\Command\RefundUnitsInterface;
 use Symfony\Component\HttpFoundation\Request;
 
 interface RefundUnitsCommandCreatorInterface
 {
-    public function fromRequest(Request $request): RefundUnits;
+    public function fromRequest(Request $request): RefundUnitsInterface;
 }