magento-test/app/code/Magento/DownloadableGraphQl/etc/graphql/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\CatalogGraphQl\Model\ProductInterfaceTypeResolverComposite">
        <arguments>
            <argument name="productTypeNameResolvers" xsi:type="array">
                <item name="downloadable_product_type_resolver" xsi:type="object">Magento\DownloadableGraphQl\Model\DownloadableProductTypeResolver</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\Framework\GraphQl\Schema\Type\Enum\DefaultDataMapper">
        <arguments>
            <argument name="map" xsi:type="array">
                <item name="DownloadableFileTypeEnum" xsi:type="array">
                    <item name="file" xsi:type="string">file</item>
                    <item name="url" xsi:type="string">url</item>
                </item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\Framework\GraphQl\Schema\Type\Entity\DefaultMapper">
        <arguments>
            <argument name="map" xsi:type="array">
                <item name="catalog_product" xsi:type="array">
                    <item name="downloadable" xsi:type="string">DownloadableProduct</item>
                </item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\QuoteGraphQl\Model\Cart\BuyRequest\BuyRequestBuilder">
        <arguments>
            <argument name="providers" xsi:type="array">
                <item name="downloadable_links" xsi:type="object">Magento\DownloadableGraphQl\Model\Cart\BuyRequest\DownloadableLinksDataProvider</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\SalesGraphQl\Model\TypeResolver\OrderItem">
        <arguments>
            <argument name="productTypeMap" xsi:type="array">
                <item name="downloadable" xsi:type="string">DownloadableOrderItem</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\SalesGraphQl\Model\TypeResolver\InvoiceItem">
        <arguments>
            <argument name="productTypeMap" xsi:type="array">
                <item name="downloadable" xsi:type="string">DownloadableInvoiceItem</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\SalesGraphQl\Model\TypeResolver\CreditMemoItem">
        <arguments>
            <argument name="productTypeMap" xsi:type="array">
                <item name="downloadable" xsi:type="string">DownloadableCreditMemoItem</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\WishlistGraphQl\Model\Resolver\Type\WishlistItemType">
        <arguments>
            <argument name="supportedTypes" xsi:type="array">
                <item name="downloadable" xsi:type="string">DownloadableWishlistItem</item>
            </argument>
        </arguments>
    </type>
    <type name="Magento\UrlRewriteGraphQl\Model\RoutableInterfaceTypeResolver">
        <arguments>
            <argument name="productTypeNameResolvers" xsi:type="array">
                <item name="downloadable_product_type_resolver" xsi:type="object">Magento\DownloadableGraphQl\Model\DownloadableProductTypeResolver</item>
            </argument>
        </arguments>
    </type>
</config>