Unit test for Magento\GiftMessage\Model\Plugin\MergeQuoteItems

app/code/Magento/GiftMessage/Test/Unit/Model/Plugin/MergeQuoteItemsTest.php

@@ -0,0 +1,87 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+declare(strict_types=1);
+
+namespace Magento\GiftMessage\Test\Unit\Model\Plugin;
+
+use Magento\Framework\TestFramework\Unit\Helper\ObjectManager as ObjectManagerHelper;
+use Magento\GiftMessage\Model\Plugin\MergeQuoteItems;
+use Magento\Quote\Model\Quote\Item;
+use Magento\Quote\Model\Quote\Item\Processor;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Unit Test for \Magento\GiftMessage\Model\Plugin\MergeQuoteItems
+ */
+class MergeQuoteItemsTest extends TestCase
+{
+    private const STUB_GIFT_MESSAGE = 'message';
+
+    /**
+     * @var MergeQuoteItems
+     */
+    private $plugin;
+
+    /**
+     * @var Processor|MockObject
+     */
+    private $processorMock;
+
+    /**
+     * @var Item|MockObject
+     */
+    private $resultMock;
+
+    /**
+     * @var Item|MockObject
+     */
+    private $sourceMock;
+
+    /**
+     * @inheritDoc
+     */
+    protected function setUp(): void
+    {
+        $this->plugin = (new ObjectManagerHelper($this))->getObject(MergeQuoteItems::class);
+        $this->processorMock = $this->createMock(Processor::class);
+        $this->resultMock = $this->createPartialMock(Item::class, ['setGiftMessageId']);
+        $this->sourceMock = $this->createPartialMock(Item::class, ['getGiftMessageId']);
+    }
+
+    /**
+     * Test case when a source item has a Gift message.
+     */
+    public function testAfterMergeExpectsSetGiftMessageIdCalled(): void
+    {
+        $this->sourceMock->expects($this->once())
+            ->method('getGiftMessageId')
+            ->willReturn(self::STUB_GIFT_MESSAGE);
+        $this->resultMock->expects($this->once())
+            ->method('setGiftMessageId')
+            ->with(self::STUB_GIFT_MESSAGE);
+
+        $this->assertSame(
+            $this->resultMock,
+            $this->plugin->afterMerge($this->processorMock, $this->resultMock, $this->sourceMock)
+        );
+    }
+
+    /**
+     * Test case when a source item doesn't have a Gift message.
+     */
+    public function testAfterMergeWithoutGiftMessageId(): void
+    {
+        $this->sourceMock->expects($this->once())->method('getGiftMessageId')->willReturn(null);
+        $this->resultMock->expects($this->never())->method('setGiftMessageId');
+
+        $this->assertSame(
+            $this->resultMock,
+            $this->plugin->afterMerge($this->processorMock, $this->resultMock, $this->sourceMock)
+        );
+    }
+}