[GRAPHQL] Made the attribute destination_cart_id for mergeCarts mutation not required.

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

@@ -7,17 +7,24 @@
 
 namespace Magento\QuoteGraphQl\Model\Resolver;
 
+use Magento\Framework\App\ObjectManager;
+use Magento\Framework\Exception\CouldNotSaveException;
 use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Exception\GraphQlAuthorizationException;
 use Magento\Framework\GraphQl\Exception\GraphQlInputException;
+use Magento\Framework\GraphQl\Exception\GraphQlNoSuchEntityException;
 use Magento\Framework\GraphQl\Query\ResolverInterface;
 use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
-use Magento\QuoteGraphQl\Model\Cart\GetCartForUser;
-use Magento\Quote\Api\CartRepositoryInterface;
 use Magento\GraphQl\Model\Query\ContextInterface;
-use Magento\Framework\GraphQl\Exception\GraphQlAuthorizationException;
+use Magento\Quote\Api\CartRepositoryInterface;
+use Magento\Quote\Model\Cart\CustomerCartResolver;
+use Magento\Quote\Model\QuoteIdToMaskedQuoteIdInterface;
+use Magento\QuoteGraphQl\Model\Cart\GetCartForUser;
 
 /**
  * Merge Carts Resolver
+ *
+ * @SuppressWarnings(PHPMD.LongVariable)
  */
 class MergeCarts implements ResolverInterface
 {
@@ -31,44 +38,95 @@ class MergeCarts implements ResolverInterface
      */
     private $cartRepository;
 
+    /**
+     * @var CustomerCartResolver
+     */
+    private $customerCartResolver;
+
+    /**
+     * @var QuoteIdToMaskedQuoteIdInterface
+     */
+    private $quoteIdToMaskedQuoteId;
+
     /**
      * @param GetCartForUser $getCartForUser
      * @param CartRepositoryInterface $cartRepository
+     * @param CustomerCartResolver|null $customerCartResolver
+     * @param QuoteIdToMaskedQuoteIdInterface|null $quoteIdToMaskedQuoteId
      */
     public function __construct(
         GetCartForUser $getCartForUser,
-        CartRepositoryInterface $cartRepository
+        CartRepositoryInterface $cartRepository,
+        CustomerCartResolver $customerCartResolver = null,
+        QuoteIdToMaskedQuoteIdInterface $quoteIdToMaskedQuoteId = null
     ) {
         $this->getCartForUser = $getCartForUser;
         $this->cartRepository = $cartRepository;
+        $this->customerCartResolver = $customerCartResolver
+            ?: ObjectManager::getInstance()->get(CustomerCartResolver::class);
+        $this->quoteIdToMaskedQuoteId = $quoteIdToMaskedQuoteId
+            ?: ObjectManager::getInstance()->get(QuoteIdToMaskedQuoteIdInterface::class);
     }
 
     /**
      * @inheritdoc
      */
-    public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
-    {
+    public function resolve(
+        Field $field,
+        $context,
+        ResolveInfo $info,
+        array $value = null,
+        array $args = null
+    ) {
         if (empty($args['source_cart_id'])) {
-            throw new GraphQlInputException(__('Required parameter "source_cart_id" is missing'));
-        }
-
-        if (empty($args['destination_cart_id'])) {
-            throw new GraphQlInputException(__('Required parameter "destination_cart_id" is missing'));
+            throw new GraphQlInputException(__(
+                'Required parameter "source_cart_id" is missing'
+            ));
         }
 
         /** @var ContextInterface $context */
         if (false === $context->getExtensionAttributes()->getIsCustomer()) {
-            throw new GraphQlAuthorizationException(__('The current customer isn\'t authorized.'));
+            throw new GraphQlAuthorizationException(__(
+                'The current customer isn\'t authorized.'
+            ));
+        }
+        $currentUserId = $context->getUserId();
+
+        if (!isset($args['destination_cart_id'])) {
+            try {
+                $cart = $this->customerCartResolver->resolve($currentUserId);
+            } catch (CouldNotSaveException $exception) {
+                throw new GraphQlNoSuchEntityException(
+                    __('Could not create empty cart for customer'),
+                    $exception
+                );
+            }
+            $customerMaskedCartId = $this->quoteIdToMaskedQuoteId->execute(
+                (int) $cart->getId()
+            );
+        } else {
+            if (empty($args['destination_cart_id'])) {
+                throw new GraphQlInputException(__(
+                    'The parameter "destination_cart_id" cannot be empty'
+                ));
+            }
         }
 
         $guestMaskedCartId = $args['source_cart_id'];
-        $customerMaskedCartId = $args['destination_cart_id'];
+        $customerMaskedCartId = $customerMaskedCartId ?? $args['destination_cart_id'];
 
-        $currentUserId = $context->getUserId();
         $storeId = (int)$context->getExtensionAttributes()->getStore()->getId();
         // passing customerId as null enforces source cart should always be a guestcart
-        $guestCart = $this->getCartForUser->execute($guestMaskedCartId, null, $storeId);
-        $customerCart = $this->getCartForUser->execute($customerMaskedCartId, $currentUserId, $storeId);
+        $guestCart = $this->getCartForUser->execute(
+            $guestMaskedCartId,
+            null,
+            $storeId
+        );
+        $customerCart = $this->getCartForUser->execute(
+            $customerMaskedCartId,
+            $currentUserId,
+            $storeId
+        );
         $customerCart->merge($guestCart);
         $guestCart->setIsActive(false);
         $this->cartRepository->save($customerCart);

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

@@ -20,7 +20,7 @@ type Mutation {
     setPaymentMethodOnCart(input: SetPaymentMethodOnCartInput): SetPaymentMethodOnCartOutput @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\SetPaymentMethodOnCart")
     setGuestEmailOnCart(input: SetGuestEmailOnCartInput): SetGuestEmailOnCartOutput @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\SetGuestEmailOnCart")
     setPaymentMethodAndPlaceOrder(input: SetPaymentMethodAndPlaceOrderInput): PlaceOrderOutput @deprecated(reason: "Should use setPaymentMethodOnCart and placeOrder mutations in single request.") @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\SetPaymentAndPlaceOrder")
-    mergeCarts(source_cart_id: String!, destination_cart_id: String!): Cart! @doc(description:"Merges the source cart into the destination cart") @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\MergeCarts")
+    mergeCarts(source_cart_id: String!, destination_cart_id: String): Cart! @doc(description:"Merges the source cart into the destination cart") @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\MergeCarts")
     placeOrder(input: PlaceOrderInput): PlaceOrderOutput @resolver(class: "\\Magento\\QuoteGraphQl\\Model\\Resolver\\PlaceOrder")
     addProductsToCart(cartId: String!, cartItems: [CartItemInput!]!): AddProductsToCartOutput @doc(description:"Add any type of product to the cart") @resolver(class: "Magento\\QuoteGraphQl\\Model\\Resolver\\AddProductsToCart")
 }

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

@@ -193,7 +193,7 @@ public function testMergeCartsWithEmptySourceCartId()
     public function testMergeCartsWithEmptyDestinationCartId()
     {
         $this->expectException(\Exception::class);
-        $this->expectExceptionMessage('Required parameter "destination_cart_id" is missing');
+        $this->expectExceptionMessage('The parameter "destination_cart_id" cannot be empty');
 
         $guestQuote = $this->quoteFactory->create();
         $this->quoteResource->load(
@@ -209,6 +209,54 @@ public function testMergeCartsWithEmptyDestinationCartId()
         $this->graphQlMutation($query, [], '', $this->getHeaderMap());
     }
 
+    /**
+     * @magentoApiDataFixture Magento/Checkout/_files/quote_with_virtual_product_saved.php
+     * @magentoApiDataFixture Magento/Customer/_files/customer.php
+     * @magentoApiDataFixture Magento/GraphQl/Catalog/_files/simple_product.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/customer/create_empty_cart.php
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/add_simple_product.php
+     */
+    public function testMergeCartsWithoutDestinationCartId()
+    {
+        $guestQuote = $this->quoteFactory->create();
+        $this->quoteResource->load(
+            $guestQuote,
+            'test_order_with_virtual_product_without_address',
+            'reserved_order_id'
+        );
+        $guestQuoteMaskedId = $this->quoteIdToMaskedId->execute((int)$guestQuote->getId());
+        $query = $this->getCartMergeMutationWithoutDestinationCartId(
+            $guestQuoteMaskedId
+        );
+        $mergeResponse = $this->graphQlMutation($query, [], '', $this->getHeaderMap());
+
+        self::assertArrayHasKey('mergeCarts', $mergeResponse);
+        $cartResponse = $mergeResponse['mergeCarts'];
+        self::assertArrayHasKey('items', $cartResponse);
+        self::assertCount(2, $cartResponse['items']);
+
+        $customerQuote = $this->quoteFactory->create();
+        $this->quoteResource->load($customerQuote, 'test_quote', 'reserved_order_id');
+        $customerQuoteMaskedId = $this->quoteIdToMaskedId->execute((int)$customerQuote->getId());
+
+        $cartResponse = $this->graphQlMutation(
+            $this->getCartQuery($customerQuoteMaskedId),
+            [],
+            '',
+            $this->getHeaderMap()
+        );
+
+        self::assertArrayHasKey('cart', $cartResponse);
+        self::assertArrayHasKey('items', $cartResponse['cart']);
+        self::assertCount(2, $cartResponse['cart']['items']);
+        $item1 = $cartResponse['cart']['items'][0];
+        self::assertArrayHasKey('quantity', $item1);
+        self::assertEquals(2, $item1['quantity']);
+        $item2 = $cartResponse['cart']['items'][1];
+        self::assertArrayHasKey('quantity', $item2);
+        self::assertEquals(1, $item2['quantity']);
+    }
+
     /**
      * Add simple product to cart
      *
@@ -256,6 +304,31 @@ private function getCartMergeMutation(string $guestQuoteMaskedId, string $custom
 QUERY;
     }
 
+    /**
+     * Create the mergeCart mutation
+     *
+     * @param string $guestQuoteMaskedId
+     * @return string
+     */
+    private function getCartMergeMutationWithoutDestinationCartId(
+        string $guestQuoteMaskedId
+    ): string {
+        return <<<QUERY
+mutation {
+  mergeCarts(
+    source_cart_id: "{$guestQuoteMaskedId}"
+  ){
+  items {
+      quantity
+      product {
+        sku
+      }
+    }
+  }
+}
+QUERY;
+    }
+
     /**
      * Get cart query
      *