[EPC-9489] Write unit tests

Test/Unit/Model/Api/GuestAdyenGiftcardTest.php

@@ -0,0 +1,72 @@
+<?php
+/**
+ *
+ * Adyen Payment module (https://www.adyen.com/)
+ *
+ * Copyright (c) 2025 Adyen N.V. (https://www.adyen.com/)
+ * See LICENSE.txt for license details.
+ *
+ * Author: Adyen <magento@adyen.com>
+ */
+
+namespace Adyen\Payment\Test\Unit\Model\Api;
+
+use Adyen\Payment\Helper\GiftcardPayment;
+use Adyen\Payment\Model\Api\GuestAdyenGiftcard;
+use Adyen\Payment\Test\Unit\AbstractAdyenTestCase;
+use Magento\Framework\Exception\NoSuchEntityException;
+use Magento\Quote\Model\MaskedQuoteIdToQuoteIdInterface;
+use PHPUnit\Framework\MockObject\MockObject;
+
+class GuestAdyenGiftcardTest extends AbstractAdyenTestCase
+{
+    protected ?GuestAdyenGiftcard $guestAdyenGiftcard;
+    protected MockObject|GiftcardPayment $giftcardPaymentHelperMock;
+    protected MockObject|MaskedQuoteIdToQuoteIdInterface $maskedQuoteIdToQuoteId;
+
+    /**
+     * @return void
+     */
+    protected function setUp(): void
+    {
+        $this->giftcardPaymentHelperMock = $this->createMock(GiftcardPayment::class);
+        $this->maskedQuoteIdToQuoteId = $this->createMock(MaskedQuoteIdToQuoteIdInterface::class);
+
+        $this->guestAdyenGiftcard = new GuestAdyenGiftcard(
+            $this->giftcardPaymentHelperMock,
+            $this->maskedQuoteIdToQuoteId
+        );
+    }
+
+    /**
+     * @return void
+     */
+    protected function tearDown(): void
+    {
+        $this->guestAdyenGiftcard = null;
+    }
+
+    /**
+     * @return void
+     * @throws NoSuchEntityException
+     */
+    public function testGetRedeemedGiftcards()
+    {
+        $cartId = 'abc_123456789_xyz';
+        $quoteId = 1;
+        $mockResponse = '{}';
+
+        $this->maskedQuoteIdToQuoteId->expects($this->once())
+            ->method('execute')
+            ->with($cartId)
+            ->willReturn($quoteId);
+
+        $this->giftcardPaymentHelperMock->expects($this->once())
+            ->method('fetchRedeemedGiftcards')
+            ->with($quoteId)
+            ->willReturn($mockResponse);
+
+        $result = $this->guestAdyenGiftcard->getRedeemedGiftcards($cartId);
+        $this->assertIsString($result);
+    }
+}