Shopping cart discount concept

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

@@ -56,6 +56,7 @@ public function resolve(Field $field, $context, ResolveInfo $info, array $value
                 'value' => $cartTotals->getSubtotalWithDiscount(), 'currency' => $currency
             ],
             'applied_taxes' => $this->getAppliedTaxes($cartTotals, $currency),
+            'discount' => $this->getDiscount($cartTotals, $currency),
             'model' => $quote
         ];
     }
@@ -84,4 +85,19 @@ private function getAppliedTaxes(Total $total, string $currency): array
         }
         return $appliedTaxesData;
     }
+
+    /**
+     * Returns information about an applied discount
+     *
+     * @param Total $total
+     * @param string $currency
+     * @return array
+     */
+    private function getDiscount(Total $total, string $currency)
+    {
+        return [
+            'label' => $total->getDiscountDescription(),
+            'amount' => ['value' => $total->getDiscountAmount(), "currency" => $currency]
+        ];
+    }
 }

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

@@ -142,6 +142,7 @@ type CartPrices {
     grand_total: Money
     subtotal_including_tax: Money
     subtotal_excluding_tax: Money
+    discount: CartDiscountItem
     subtotal_with_discount_excluding_tax: Money
     applied_taxes: [CartTaxItem]
 }
@@ -151,6 +152,11 @@ type CartTaxItem {
     label: String!
 }
 
+type CartDiscountItem {
+    amount: Money!
+    label: String!
+}
+
 type SetPaymentMethodOnCartOutput {
     cart: Cart!
 }

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

@@ -87,7 +87,6 @@ public function testGetTotalsWithNoTaxApplied()
      * @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
-     * @group recent
      */
     public function testGetCartTotalsWithNoAddressSet()
     {
@@ -125,6 +124,34 @@ public function testGetSelectedShippingMethodFromCustomerCart()
         $this->graphQlQuery($query);
     }
 
+    /**
+     * @magentoApiDataFixture Magento/GraphQl/Quote/_files/cart_rule_discount_no_coupon.php
+     * @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
+     * @group recent
+     */
+    public function testGetDiscountInformation()
+    {
+        $maskedQuoteId = $this->getMaskedQuoteIdByReservedOrderId->execute('test_quote');
+        $query = $this->getQuery($maskedQuoteId);
+        $response = $this->graphQlQuery($query);
+
+        $discountResponse = $response['cart']['prices']['discount'];
+        self::assertEquals(-20, $discountResponse['amount']['value']);
+        self::assertEquals('100% Off for all orders', $discountResponse['label']);
+    }
+
+    public function testGetDiscountInformationWithTwoRulesApplied()
+    {
+        self::fail();
+    }
+
+    public function testGetDiscountInformationForRuleWithNoLabel()
+    {
+        self::fail();
+    }
+
     /**
      * Generates GraphQl query for retrieving cart totals
      *
@@ -160,6 +187,13 @@ private function getQuery(string $maskedQuoteId): string
           currency
         }
       }
+      discount {
+        label
+        amount {
+          value
+          currency
+        }
+      }
     }
   }
 }

dev/tests/integration/testsuite/Magento/GraphQl/Quote/_files/cart_rule_discount_no_coupon.php

@@ -0,0 +1,52 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+use Magento\Customer\Model\GroupManagement as CustomerGroupManagement;
+use Magento\Framework\Api\DataObjectHelper;
+use Magento\SalesRule\Api\RuleRepositoryInterface;
+use Magento\SalesRule\Model\Data\Rule as RuleData;
+use Magento\Store\Model\StoreManagerInterface as StoreManagerInterface;
+use Magento\TestFramework\Helper\Bootstrap;
+
+
+$objectManager = Bootstrap::getObjectManager();
+/** @var RuleRepositoryInterface $ruleRepository */
+$ruleRepository = $objectManager->get(RuleRepositoryInterface::class);
+/** @var DataObjectHelper $dataObjectHelper */
+$dataObjectHelper = Bootstrap::getObjectManager()->get(DataObjectHelper::class);
+$ruleLabel = $objectManager->create(\Magento\SalesRule\Api\Data\RuleLabelInterface::class);
+$ruleLabelFactory = $objectManager->get(\Magento\SalesRule\Model\Data\RuleLabelFactory::class);
+
+
+/** @var RuleData $salesRule */
+$salesRule = $objectManager->create(RuleData::class);
+/** @var \Magento\SalesRule\Api\Data\RuleLabelInterface $ruleLabel */
+$ruleLabel = $ruleLabelFactory->create();
+$ruleLabel->setStoreId(0);
+$ruleLabel->setStoreLabel('50% Off for all orders');
+$ruleData = [
+        'name' => '50% Off for all orders',
+        'is_active' => 1,
+        'customer_group_ids' => [CustomerGroupManagement::NOT_LOGGED_IN_ID],
+        'coupon_type' => RuleData::COUPON_TYPE_NO_COUPON,
+        'conditions' => [],
+        'simple_action' => 'by_percent',
+        'discount_amount' => 50,
+        'discount_step' => 0,
+        'website_ids' => [
+            $objectManager->get(
+                StoreManagerInterface::class
+            )->getWebsite()->getId(),
+        ],
+        'discount_qty' => 0,
+        'apply_to_shipping' => 1,
+        'simple_free_shipping' => 1,
+];
+$dataObjectHelper->populateWithArray($salesRule, $ruleData, \Magento\SalesRule\Api\Data\RuleInterface::class);
+$salesRule->setStoreLabels([$ruleLabel]);
+
+$ruleRepository->save($salesRule);

dev/tests/integration/testsuite/Magento/GraphQl/Quote/_files/cart_rule_discount_no_coupon_rollback.php

@@ -0,0 +1,26 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+use Magento\SalesRule\Api\RuleRepositoryInterface;
+use Magento\SalesRule\Model\ResourceModel\Rule as RuleResource;
+use Magento\SalesRule\Model\RuleFactory as RuleFactory;
+use Magento\TestFramework\Helper\Bootstrap;
+
+$objectManager = Bootstrap::getObjectManager();
+/** @var RuleRepositoryInterface $ruleRepository */
+$ruleRepository = $objectManager->get(RuleRepositoryInterface::class);
+/** @var RuleResource $ruleResource */
+$ruleResource = $objectManager->get(RuleResource::class);
+/** @var RuleFactory $ruleFactory */
+$ruleFactory = $objectManager->get(RuleFactory::class);
+$salesRule = $ruleFactory->create();
+
+$ruleResource->load($salesRule, '50% Off for all orders', 'name');
+// FIXME: the rule cannot be found for some reason
+if ($salesRule->getRuleId()) {
+    $ruleRepository->deleteById($salesRule->getRuleId());
+}

dev/tests/integration/testsuite/Magento/SalesRule/_files/cart_rule_100_percent_off_rollback.php

@@ -5,11 +5,19 @@
  */
 declare(strict_types=1);
 
+use Magento\Framework\Registry;
+use Magento\SalesRule\Api\RuleRepositoryInterface;
+use Magento\TestFramework\Helper\Bootstrap;
+
+$objectManager = Bootstrap::getObjectManager();
 /** @var Magento\Framework\Registry $registry */
-$registry = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()->get(\Magento\Framework\Registry::class);
+$registry = Bootstrap::getObjectManager()->get(Registry::class);
+/** @var RuleRepositoryInterface $ruleRepository */
+$ruleRepository = $objectManager->get(RuleRepositoryInterface::class);
 
 /** @var Magento\SalesRule\Model\Rule $rule */
-$rule = $registry->registry('cart_rule_100_percent_off');
-if ($rule) {
-    $rule->delete();
+$ruleId = $registry->registry('Magento/SalesRule/_files/cart_rule_100_percent_off');
+
+if ($ruleId) {
+    $ruleRepository->deleteById($ruleId);
 }