MC-19255: API functional tests to cover cart promotions

- added additional validation for no discount

Author: dthampy

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

@@ -335,6 +335,36 @@ public function testCartPromotionsWithCoupons()
         $this->assertEquals($response['cart']['prices']['discounts'][0]['amount']['value'], 5);
     }
 
+    /**
+     * If no discount is applicable to the cart, row total discount should be zero and no rule label shown
+     *
+     * @magentoApiDataFixture Magento/Catalog/_files/multiple_products.php
+     * @magentoApiDataFixture Magento/SalesRule/_files/buy_3_get_1_free.php
+     */
+    public function testCartPromotionsWhenNoDiscountIsAvailable()
+    {
+        $objectManager = Bootstrap::getObjectManager();
+        /** @var ProductRepositoryInterface $productRepository */
+        $productRepository = $objectManager->get(ProductRepositoryInterface::class);
+        /** @var Product $prod2 */
+        $prod1 = $productRepository->get('simple1');
+        $prod2 = $productRepository->get('simple2');
+        $productsInCart = [$prod1, $prod2];
+        $prod2->setVisibility(Visibility::VISIBILITY_BOTH);
+        $productRepository->save($prod2);
+        $skus =['simple1', 'simple2'];
+        $qty = 2;
+        $cartId = $this->createEmptyCart();
+        $this->addMultipleSimpleProductsToCart($cartId, $qty, $skus[0], $skus[1]);
+        $query = $this->getCartItemPricesQuery($cartId);
+        $response = $this->graphQlMutation($query);
+        $this->assertCount(2, $response['cart']['items']);
+        foreach ($response['cart']['items'] as $cartItems) {
+            $this->assertEquals(0, $cartItems['prices']['total_item_discount']['value']);
+            $this->assertNull($cartItems['prices']['discounts']);
+        }
+    }
+
     /**
      * Validating if the discount label in the response shows the default value if no label is available on cart rule
      *

dev/tests/integration/testsuite/Magento/SalesRule/_files/buy_3_get_1_free.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+use Magento\Customer\Model\GroupManagement;
+use Magento\SalesRule\Model\Rule;
+use Magento\Store\Model\StoreManagerInterface;
+use Magento\TestFramework\Helper\Bootstrap;
+
+$objectManager = Bootstrap::getObjectManager();
+
+/** @var Rule $salesRule */
+$salesRule = $objectManager->create(Rule::class);
+$salesRule->setData(
+    [
+        'name' => 'Buy 3 And Get 1 Free',
+        'is_active' => 1,
+        'customer_group_ids' => [GroupManagement::NOT_LOGGED_IN_ID],
+        'coupon_type' => Rule::COUPON_TYPE_NO_COUPON,
+        'conditions' => [],
+        'simple_action' => Rule::BUY_X_GET_Y_ACTION,
+        'discount_amount' => 1,
+        'discount_step' => 3,
+        'stop_rules_processing' => 0,
+        'store_labels' => [0 => ' Get 1 item free for every 3 you buy'],
+        'website_ids' => [
+            $objectManager->get(StoreManagerInterface::class)->getWebsite()->getId(),
+        ],
+    ]
+);
+$objectManager->get(\Magento\SalesRule\Model\ResourceModel\Rule::class)->save($salesRule);

dev/tests/integration/testsuite/Magento/SalesRule/_files/buy_3_get_1_free_rollback.php

@@ -0,0 +1,9 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+// phpcs:ignore Magento2.Security.IncludeFile
+require __DIR__ . '/rules_rollback.php';

dev/tests/integration/testsuite/Magento/SalesRule/_files/cart_rule_10_percent_off_qty_more_than_2_items.php

@@ -27,6 +27,7 @@
         'discount_amount' => 10,
         'discount_step' => 0,
         'stop_rules_processing' => 1,
+        'is_advanced' => 1,
         'website_ids' => [$websiteId],
         'store_labels' => [