magento-test/app/code/Magento/GiftMessage/etc/di.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Framework\Module\Setup\Migration">
        <arguments>
            <argument name="compositeModules" xsi:type="array">
                <item name="giftmessage" xsi:type="string">Magento_GiftMessage</item>
            </argument>
        </arguments>
    </type>
    <preference for="Magento\GiftMessage\Api\CartRepositoryInterface" type="Magento\GiftMessage\Model\CartRepository"/>
    <preference for="Magento\GiftMessage\Api\ItemRepositoryInterface" type="Magento\GiftMessage\Model\ItemRepository"/>
    <preference for="Magento\GiftMessage\Api\GuestCartRepositoryInterface" type="Magento\GiftMessage\Model\GuestCartRepository"/>
    <preference for="Magento\GiftMessage\Api\GuestItemRepositoryInterface" type="Magento\GiftMessage\Model\GuestItemRepository"/>
    <preference for="Magento\GiftMessage\Api\OrderRepositoryInterface" type="Magento\GiftMessage\Model\OrderRepository"/>
    <preference for="Magento\GiftMessage\Api\OrderItemRepositoryInterface" type="Magento\GiftMessage\Model\OrderItemRepository"/>
    <preference for="Magento\GiftMessage\Api\Data\MessageInterface" type="Magento\GiftMessage\Model\Message"/>
    <type name="Magento\GiftMessage\Model\Plugin\QuoteItem" shared="false" />
    <type name="Magento\Quote\Model\Quote\Item\ToOrderItem">
        <plugin name="gift_message_quote_item_conversion" type="Magento\GiftMessage\Model\Plugin\QuoteItem"/>
    </type>
    <type name="Magento\Sales\Api\OrderRepositoryInterface">
        <plugin name="save_gift_message" type="Magento\GiftMessage\Model\Plugin\OrderSave"/>
        <plugin name="get_gift_message" type="Magento\GiftMessage\Model\Plugin\OrderGet"/>
    </type>
    <type name="Magento\Eav\Model\Config">
        <arguments>
            <argument name="attributesForPreload" xsi:type="array">
                <item name="catalog_product" xsi:type="array">
                    <item name="gift_message_available" xsi:type="string">catalog_product</item>
                </item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\Sales\Api\OrderItemRepositoryInterface">
        <plugin name="get_gift_message" type="Magento\GiftMessage\Model\Plugin\OrderItemGet"/>
    </type>
</config>