BUG#AC-1084:GraphQl subtotal_with_discount_excluding_tax is calculated using discount including tax - issue fixed

Author: glo80326

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

@@ -17,7 +17,6 @@
 use Magento\Quote\Model\Quote\Address\Total;
 use Magento\QuoteGraphQl\Model\Cart\TotalsCollector;
 use Magento\Store\Model\ScopeInterface;
-use Magento\Tax\Model\Config;
 
 /**
  * @inheritdoc
@@ -132,7 +131,7 @@ private function getDiscount(Total $total, string $currency)
     private function getSubtotalWithDiscountExcludingTax(Total $cartTotals): float
     {
         $discountIncludeTax = $this->scopeConfig->getValue(
-            Config::CONFIG_XML_PATH_DISCOUNT_TAX,
+            'tax/calculation/discount_tax',
             ScopeInterface::SCOPE_STORE
         ) ?? 0;
         $discountExclTax = $discountIncludeTax ?

app/code/Magento/QuoteGraphQl/Test/Unit/Model/Resolver/CartPricesTest.php

@@ -0,0 +1,148 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\QuoteGraphQl\Test\Unit\Model\Resolver;
+
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\Exception\LocalizedException;
+use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
+use Magento\GraphQl\Model\Query\Context;
+use Magento\Quote\Model\Quote;
+use Magento\Quote\Model\Quote\Address\Total;
+use Magento\QuoteGraphQl\Model\Cart\TotalsCollector;
+use Magento\QuoteGraphQl\Model\Resolver\CartPrices;
+use PHPUnit\Framework\TestCase;
+use PHPUnit\Framework\MockObject\MockObject;
+
+/**
+ * @see CartPrices
+ */
+class CartPricesTest extends TestCase
+{
+    /**
+     * @var CartPrices
+     */
+    private CartPrices $cartPrices;
+
+    /**
+     * @var TotalsCollector|MockObject
+     */
+    private TotalsCollector $totalsCollectorMock;
+
+    /**
+     * @var ScopeConfigInterface|MockObject
+     */
+    private ScopeConfigInterface $scopeConfigMock;
+
+    /**
+     * @var Field|MockObject
+     */
+    private Field $fieldMock;
+
+    /**
+     * @var ResolveInfo|MockObject
+     */
+    private ResolveInfo $resolveInfoMock;
+
+    /**
+     * @var Context|MockObject
+     */
+    private Context $contextMock;
+
+    /**
+     * @var Quote|MockObject
+     */
+    private Quote $quoteMock;
+
+    /**
+     * @var Total|MockObject
+     */
+    private Total $totalMock;
+
+    /**
+     * @var array
+     */
+    private array $valueMock = [];
+
+    protected function setUp(): void
+    {
+        $this->totalsCollectorMock = $this->createMock(TotalsCollector::class);
+        $this->scopeConfigMock = $this->createMock(ScopeConfigInterface::class);
+        $this->fieldMock = $this->createMock(Field::class);
+        $this->resolveInfoMock = $this->createMock(ResolveInfo::class);
+        $this->contextMock = $this->createMock(Context::class);
+        $this->quoteMock = $this->getMockBuilder(Quote::class)
+            ->disableOriginalConstructor()
+            ->addMethods(['getQuoteCurrencyCode'])
+            ->getMock();
+        $this->totalMock = $this->getMockBuilder(Total::class)
+            ->disableOriginalConstructor()
+            ->addMethods(
+                [
+                    'getSubtotal',
+                    'getSubtotalInclTax',
+                    'getGrandTotal',
+                    'getDiscountTaxCompensationAmount',
+                    'getDiscountAmount',
+                    'getDiscountDescription',
+                    'getAppliedTaxes'
+                ]
+            )
+            ->getMock();
+        $this->cartPrices = new CartPrices(
+            $this->totalsCollectorMock,
+            $this->scopeConfigMock
+        );
+    }
+
+    public function testResolveWithoutModelInValueParameter(): void
+    {
+        $this->expectException(LocalizedException::class);
+        $this->expectExceptionMessage('"model" value should be specified');
+        $this->cartPrices->resolve($this->fieldMock, $this->contextMock, $this->resolveInfoMock, $this->valueMock);
+    }
+
+    public function testResolve(): void
+    {
+        $this->valueMock = ['model' => $this->quoteMock];
+        $this->quoteMock
+            ->expects($this->once())
+            ->method('getQuoteCurrencyCode')
+            ->willReturn('USD');
+        $this->totalMock
+            ->expects($this->once())
+            ->method('getGrandTotal');
+        $this->totalMock
+            ->expects($this->exactly(2))
+            ->method('getSubtotal');
+        $this->totalMock
+            ->expects($this->once())
+            ->method('getSubtotalInclTax');
+        $this->totalMock
+            ->expects($this->once())
+            ->method('getDiscountDescription')
+            ->willReturn('Discount Description');
+        $this->totalMock
+            ->expects($this->once())
+            ->method('getAppliedTaxes');
+        $this->scopeConfigMock
+            ->expects($this->once())
+            ->method('getValue')
+            ->willReturn(1);
+        $this->totalMock
+            ->expects($this->atLeast(2))
+            ->method('getDiscountAmount');
+        $this->totalMock
+            ->expects($this->once())
+            ->method('getDiscountTaxCompensationAmount');
+        $this->totalsCollectorMock
+            ->method('collectQuoteTotals')
+            ->willReturn($this->totalMock);
+        $this->cartPrices->resolve($this->fieldMock, $this->contextMock, $this->resolveInfoMock, $this->valueMock);
+    }
+}