ENGCOM-5678: Add total_quantity to cart response object #843

 - Merge Pull Request magento/graphql-ce#843 from pmclain/graphql-ce:issue/827
 - Merged commits:
   1. 6f66bed
   2. d6a2fc8
   3. f6f0aef
   4. fc5a7ff
   5. eae167e

Author: magento-engcom-team

app/code/Magento/QuoteGraphQl/Model/Resolver/CartTotalQuantity.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\QuoteGraphQl\Model\Resolver;
+
+use Magento\Framework\Exception\LocalizedException;
+use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Query\ResolverInterface;
+use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
+use Magento\Quote\Model\Quote;
+
+/**
+ * @inheritdoc
+ */
+class CartTotalQuantity implements ResolverInterface
+{
+    /**
+     * @inheritdoc
+     */
+    public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
+    {
+        if (!isset($value['model'])) {
+            throw new LocalizedException(__('"model" value should be specified'));
+        }
+        /** @var Quote $cart */
+        $cart = $value['model'];
+
+        return (float)$cart->getItemsSummaryQty();
+    }
+}

app/code/Magento/QuoteGraphQl/etc/schema.graphqls

@@ -197,6 +197,7 @@ type Cart {
     available_payment_methods: [AvailablePaymentMethod] @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\AvailablePaymentMethods") @doc(description: "Available payment methods")
     selected_payment_method: SelectedPaymentMethod @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\SelectedPaymentMethod")
     prices: CartPrices @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\CartPrices")
+    total_quantity: Float! @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\CartTotalQuantity")
 }
 
 interface CartAddressInterface @typeResolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\CartAddressTypeResolver") {

dev/tests/api-functional/testsuite/Magento/GraphQl/Quote/GetCartTotalQuantityTest.php

@@ -0,0 +1,64 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\GraphQl\Quote;
+
+use Magento\TestFramework\Helper\Bootstrap;
+use Magento\TestFramework\TestCase\GraphQlAbstract;
+
+/**
+ * Test for getting total quantity from cart query
+ */
+class GetCartTotalQuantityTest extends GraphQlAbstract
+{
+    /**
+     * @var GetMaskedQuoteIdByReservedOrderId
+     */
+    private $getMaskedQuoteIdByReservedOrderId;
+
+    protected function setUp()
+    {
+        $objectManager = Bootstrap::getObjectManager();
+        $this->getMaskedQuoteIdByReservedOrderId = $objectManager->get(GetMaskedQuoteIdByReservedOrderId::class);
+    }
+
+    /**
+     * @magentoApiDataFixture Magento/GraphQl/Catalog/_files/simple_product.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/guest/create_empty_cart.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/add_simple_product.php
+     */
+    public function testGetTotalQuantity()
+    {
+        $maskedQuoteId = $this->getMaskedQuoteIdByReservedOrderId->execute('test_quote');
+
+        $query = $this->getQuery($maskedQuoteId);
+
+        $response = $this->graphQlQuery($query);
+
+        self::assertArrayHasKey('cart', $response);
+        $cart = $response['cart'];
+        self::assertArrayHasKey('total_quantity', $cart);
+        self::assertEquals(2, $cart['total_quantity']);
+    }
+
+    /**
+     * Create cart query
+     *
+     * @param string $maskedQuoteId
+     * @return string
+     */
+    private function getQuery(string $maskedQuoteId): string
+    {
+        return <<<QUERY
+{
+  cart(cart_id: "{$maskedQuoteId}") {
+    total_quantity
+  }
+}
+QUERY;
+    }
+}