ACP2E-3498: Incorrect discount value when multiple cart price rules are applied simultaneously with discounted/special priced products

Author: aplapana

app/code/Magento/SalesRule/Model/Rule/Action/Discount/CartFixed.php

@@ -93,7 +93,6 @@ public function calculate($rule, $item, $qty)
         $baseItemPrice = $this->validator->getItemBasePrice($item);
         $itemOriginalPrice = $this->validator->getItemOriginalPrice($item);
         $baseItemOriginalPrice = $this->validator->getItemBaseOriginalPrice($item);
-        $baseItemDiscountAmount = (float) $item->getBaseDiscountAmount();
 
         $cartRules = $quote->getCartFixedRules();
         if (!isset($cartRules[$rule->getId()])) {
@@ -132,8 +131,8 @@ public function calculate($rule, $item, $qty)
                         $ruleDiscount,
                         $qty,
                         $baseItemPrice,
-                        $baseItemDiscountAmount,
-                        $baseRuleTotals - $baseItemDiscountAmount,
+                        0,
+                        $baseRuleTotals,
                         $discountType
                     );
             }

dev/tests/integration/testsuite/Magento/SalesRule/Model/Rule/Action/Discount/CartFixedTest.php

@@ -1,7 +1,7 @@
 <?php
 /**
- * Copyright © Magento, Inc. All rights reserved.
- * See COPYING.txt for license details.
+ * Copyright 2018 Adobe
+ * All Rights Reserved.
  */
 declare(strict_types=1);
 
@@ -526,11 +526,11 @@ public static function discountByPercentDataProvider()
             ],
             [
                 'percentDiscount' => 15.5,
-                'expectedDiscounts' => ['simple1' => 3.65, 'simple2' => 9.76, 'totalDiscount' => -13.41]
+                'expectedDiscounts' => ['simple1' => 3.66, 'simple2' => 9.75, 'totalDiscount' => -13.41]
             ],
             [
                 'percentDiscount' => 50,
-                'expectedDiscounts' => ['simple1' => 5.72, 'simple2' => 15.27, 'totalDiscount' => -20.99]
+                'expectedDiscounts' => ['simple1' => 5.73, 'simple2' => 15.26, 'totalDiscount' => -20.99]
             ],
             [
                 'percentDiscount' => 100,