Refactor Code and write Unit test

config/item_mapping.php

@@ -0,0 +1,9 @@
+<?php 
+
+return [
+    'Aged Brie'         => 'GildedRose\Items\AgedBrieItem',
+    'Backstage passes'  => 'GildedRose\Items\BackstagePassItem',
+    'Sulfuras'          => 'GildedRose\Items\SulfurasItem',
+    'Conjured'          => 'GildedRose\Items\ConjuredItem',
+    // Add more mappings here...
+];

src/GildedRose.php

@@ -18,8 +18,13 @@ final class GildedRose
 
     public function updateQuality(): void
     {
+        // We don't use symfony, so tempory load the mapping file simple like this.
+        // In symfony we can use ParameterBagInterface to load yaml config
+        $mappingFile = __DIR__ . '/../config/item_mapping.php';
+        $itemFactory = new ItemFactory($mappingFile);
+
         foreach ($this->items as $item) {
-            $itemInstance = ItemFactory::createItem($item);
+            $itemInstance = $itemFactory->createItem($item);
             $itemInstance->updateSellIn($item);
             $itemInstance->updateQuality($item);
         }

src/Items/Factory/ItemFactory.php

@@ -5,31 +5,35 @@ declare(strict_types=1);
 namespace GildedRose\Items\Factory;
 
 use GildedRose\Item;
-use GildedRose\Items\AgedBrieItem;
-use GildedRose\Items\BackstagePassItem;
-use GildedRose\Items\ConjuredItem;
 use GildedRose\Items\Interface\ItemInterface;
 use GildedRose\Items\NormalItem;
-use GildedRose\Items\SulfurasItem;
 
 class ItemFactory
 {
-    public const AGED_BRIE_ITEM = 'Aged Brie';
+    private array $itemMappings;
 
-    public const BACKSTAGE_ITEM = 'Backstage';
+    public function __construct(string $configFilePath)
-
-    public const SULFURAS_ITEM = 'Sulfuras';
-
-    public const CONJURED_ITEM = 'Conjured';
-
-    public static function createItem(Item $item): ItemInterface
     {
-        return match (true) {
+        $this->itemMappings = require $configFilePath;
-            str_contains($item->name, self::AGED_BRIE_ITEM) => new AgedBrieItem(),
+    }
-            str_contains($item->name, self::BACKSTAGE_ITEM) => new BackstagePassItem(),
+
-            str_contains($item->name, self::SULFURAS_ITEM) => new SulfurasItem(),
+    public function createItem(Item $item): ItemInterface
-            str_contains($item->name, self::CONJURED_ITEM) => new ConjuredItem(),
+    {
-            default => new NormalItem()
+        foreach ($this->itemMappings as $itemName => $itemClassName) {
-        };
+            if (! class_exists($itemClassName)) {
+                throw new \RuntimeException(sprintf('Class "%s" does not exist', $itemClassName));
+            }
+
+            if (str_contains($item->name, $itemName)) {
+                $reflection = new \ReflectionClass($itemClassName);
+                $instance = $reflection->newInstance();
+
+                if (! $instance instanceof ItemInterface) {
+                    throw new \RuntimeException(sprintf('Class "%s" does not implement ItemInterface', $itemClassName));
+                }
+                return $instance;
+            }
+        }
+        return new NormalItem();
     }
 }

tests/GildedRoseTest.php

@@ -79,7 +79,7 @@ class GildedRoseTest extends TestCase
     public function testBackstageIncreaseQualityBy2WhenSellInLessThanOrEqual10(): void
     {
         $items = [
-            new Item('Backstage', 9, 10),
+            new Item('Backstage passes', 9, 10),
         ];
         $GildedRose = new GildedRose($items);
         $GildedRose->updateQuality();
@@ -90,7 +90,7 @@ class GildedRoseTest extends TestCase
     public function testBackstageIncreaseQualityBy3WhenSellInLessThanOrEqual5(): void
     {
         $items = [
-            new Item('Backstage', 4, 10),
+            new Item('Backstage passes', 4, 10),
         ];
         $GildedRose = new GildedRose($items);
         $GildedRose->updateQuality();
@@ -101,7 +101,7 @@ class GildedRoseTest extends TestCase
     public function testBackstageSetQualityZeroWhenSellInLessThanOrEqualZero(): void
     {
         $items = [
-            new Item('Backstage', 0, 10),
+            new Item('Backstage passes', 0, 10),
         ];
         $GildedRose = new GildedRose($items);
         $GildedRose->updateQuality();