Add conjured items feature

php/src/GildedRose.php

@@ -9,6 +9,7 @@ final class GildedRose
     private const AGED_BRIE = 'Aged Brie';
     private const BACKSTAGE = 'Backstage passes to a TAFKAL80ETC concert';
     private const SHR = 'Sulfuras, Hand of Ragnaros';
+    private const CONJURED = 'Conjured Mana Cake';
 
     private const MAX_THRESHOLD = 50;
     private const MIN_THRESHOLD = 0;
@@ -33,6 +34,11 @@ final class GildedRose
                 $item->quality = $this->subtractQuality($item);
             }
 
+            // The quality of conjured items degrade twice as fast as normal items, so subtract once again
+            if ($this->isConjuredItem($item)) {
+                $item->quality = $this->subtractQuality($item);
+            }
+
             if ($this->qualityIncreases($item)) {
                 $item->quality = $this->addQuality($item);
 
@@ -84,6 +90,11 @@ final class GildedRose
         return $item->sell_in < 0;
     }
 
+    private function isConjuredItem(Item $item): bool
+    {
+        return $item->name === self::CONJURED;
+    }
+
     private function subtractQuality(Item $item): int
     {
         $quality = $item->quality;

php/tests/GildedRoseTest.php

@@ -16,6 +16,7 @@ class GildedRoseTest extends TestCase
             new Item('+5 Dexterity Vest', 10, 20),
             new Item('Aged Brie', 2, 0),
             new Item('Sulfuras, Hand of Ragnaros', 0, 80),
+            new Item('Conjured Mana Cake', 1, 6),
         ];
 
         $gildedRose = new GildedRose($items);
@@ -30,5 +31,8 @@ class GildedRoseTest extends TestCase
 
         $this->assertSame(0, $items[2]->sell_in);
         $this->assertSame(80, $items[2]->quality);
+
+        $this->assertSame(0, $items[3]->sell_in);
+        $this->assertSame(4, $items[3]->quality);
     }
 }