add test coverage and some changes

Author: Usik2203

app/code/Magento/CatalogCustomerGraphQl/Model/Resolver/PriceTiers.php

@@ -169,11 +169,11 @@ private function formatProductTierPrices(array $tierPrices, float $productPrice,
     private function filterTierPrices(array $tierPrices): array
     {
         $qtyCache = [];
-        foreach ($tierPrices as $item => &$price) {
+        foreach ($tierPrices as $item => $price) {
             $qty = $price->getQty();
             if (isset($qtyCache[$qty])) {
                 $priceQty = $qtyCache[$qty];
-                if ($this->isFirstPriceBetter((float)$price->getValue(), (float)$tierPrices[$priceQty]->getValue())) {
+                if ((float)$price->getValue() < (float)$tierPrices[$priceQty]->getValue()) {
                     unset($tierPrices[$priceQty]);
                     $qtyCache[$priceQty] = $item;
                 } else {
@@ -186,17 +186,4 @@ private function filterTierPrices(array $tierPrices): array
 
         return $tierPrices;
     }
-
-    /**
-     * Returns true if first price is better
-     *
-     * @param float $firstPrice
-     * @param float $secondPrice
-     *
-     * @return bool
-     */
-    private function isFirstPriceBetter(float $firstPrice, float $secondPrice): bool
-    {
-        return $firstPrice < $secondPrice;
-    }
 }

dev/tests/api-functional/testsuite/Magento/GraphQl/CatalogCustomer/PriceTiersTest.php

@@ -8,10 +8,10 @@
 namespace Magento\GraphQl\CatalogCustomer;
 
 use Magento\GraphQl\GetCustomerAuthenticationHeader;
-use Magento\TestFramework\TestCase\GraphQlAbstract;
 use Magento\Store\Api\StoreRepositoryInterface;
 use Magento\TestFramework\Helper\Bootstrap;
 use Magento\TestFramework\ObjectManager;
+use Magento\TestFramework\TestCase\GraphQlAbstract;
 
 class PriceTiersTest extends GraphQlAbstract
 {
@@ -101,6 +101,20 @@ public function testSecondStoreViewWithCurrencyRate()
         $this->assertEquals(round(7.25 * $rate, 2), $this->getValueForQuantity(5, $itemTiers));
     }
 
+    /**
+     * @magentoApiDataFixture Magento/Catalog/_files/simple_product_with_price_tiers_for_multiple_groups.php
+     */
+    public function testGetLowersPrices()
+    {
+        $productSku = 'simple';
+        $query = $this->getProductSearchQuery($productSku);
+        $response = $this->graphQlQuery($query);
+        $itemTiers = $response['products']['items'][0]['price_tiers'];
+        $this->assertCount(2, $itemTiers);
+        $this->assertEquals(round(8.25, 2), $this->getValueForQuantity(3, $itemTiers));
+        $this->assertEquals(round(7.25, 2), $this->getValueForQuantity(5, $itemTiers));
+    }
+
     /**
      * Get the tier price value for the given product quantity
      *

dev/tests/integration/testsuite/Magento/Catalog/_files/simple_product_with_price_tiers_for_multiple_groups.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+use Magento\Catalog\Api\Data\ProductTierPriceInterfaceFactory;
+use Magento\Catalog\Api\Data\ProductTierPriceExtensionFactory;
+use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\Customer\Model\Group;
+use Magento\Store\Api\WebsiteRepositoryInterface;
+use Magento\TestFramework\Helper\Bootstrap;
+use Magento\TestFramework\Workaround\Override\Fixture\Resolver;
+
+Resolver::getInstance()->requireDataFixture('Magento/Catalog/_files/product_simple.php');
+
+$objectManager = Bootstrap::getObjectManager();
+$productRepository = $objectManager->create(ProductRepositoryInterface::class);
+$tierPriceFactory = $objectManager->get(ProductTierPriceInterfaceFactory::class);
+$tpExtensionAttributesFactory = $objectManager->get(ProductTierPriceExtensionFactory::class);
+$product = $productRepository->get('simple', false, null, true);
+$adminWebsite = $objectManager->get(WebsiteRepositoryInterface::class)->get('admin');
+$tierPriceExtensionAttributes = $tpExtensionAttributesFactory->create()->setWebsiteId($adminWebsite->getId());
+$pricesForCustomerGroupsInput = [
+    [
+        'customer_group_id' => Group::CUST_GROUP_ALL,
+        'percentage_value'=> null,
+        'qty'=> 3,
+        'value'=> 9.25
+    ],
+    [
+        'customer_group_id' => Group::NOT_LOGGED_IN_ID,
+        'percentage_value'=> null,
+        'qty'=> 3,
+        'value'=> 8.25
+    ],
+    [
+        'customer_group_id' => Group::CUST_GROUP_ALL,
+        'percentage_value'=> null,
+        'qty'=> 5,
+        'value'=> 7.25
+    ],
+    [
+        'customer_group_id' => Group::NOT_LOGGED_IN_ID,
+        'percentage_value'=> null,
+        'qty'=> 5,
+        'value'=> 9
+    ]
+];
+$productTierPrices = [];
+foreach ($pricesForCustomerGroupsInput as $price) {
+    $productTierPrices[] = $tierPriceFactory->create(
+        [
+            'data' => $price
+        ]
+    )->setExtensionAttributes($tierPriceExtensionAttributes);
+}
+$product->setTierPrices($productTierPrices);
+$productRepository->save($product);

dev/tests/integration/testsuite/Magento/Catalog/_files/simple_product_with_price_tiers_for_multiple_groups_rollback.php

@@ -0,0 +1,10 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+use Magento\TestFramework\Workaround\Override\Fixture\Resolver;
+
+Resolver::getInstance()->requireDataFixture('Magento/Catalog/_files/product_simple_rollback.php');