feat: add ConjuredStrategy

python/gilded_rose.py

@@ -83,6 +83,22 @@ class SulfurasStrategy:
         pass  # legendary items are immutable; parameters required by Protocol
 
 
+class ConjuredStrategy:
+    """
+    Double-degradation strategy for Conjured items.
+
+    Quality decreases by 2 per day; by 4 per day once the sell date
+    has passed. Quality never falls below 0.
+    """
+
+    def update(self, item: "Item", days: int) -> None:
+        for _ in range(days):
+            item.quality = max(0, item.quality - 2)
+            item.sell_in -= 1
+            if item.sell_in < 0:
+                item.quality = max(0, item.quality - 2)
+
+
 class GildedRose(object):
 
     def __init__(self, items):

python/tests/test_gilded_rose.py

@@ -9,7 +9,7 @@ if str(_EXERCISE_ROOT) not in sys.path:
 
 from gilded_rose import (
     Item, GildedRose, NormalStrategy, AgedBrieStrategy,
-    BackstagePassStrategy, SulfurasStrategy,
+    BackstagePassStrategy, SulfurasStrategy, ConjuredStrategy,
 )
 
 
@@ -169,5 +169,43 @@ class TestSulfurasStrategy(unittest.TestCase):
         self.assertEqual(0, item.sell_in)
 
 
+class TestConjuredStrategy(unittest.TestCase):
+    """Tests for ConjuredStrategy — degrades twice as fast as normal."""
+
+    def setUp(self):
+        self.strategy = ConjuredStrategy()
+
+    def test_quality_decrements_by_2_each_day(self):
+        item = Item("Conjured Mana Cake", sell_in=10, quality=20)
+        self.strategy.update(item, days=1)
+        self.assertEqual(18, item.quality)
+        self.assertEqual(9, item.sell_in)
+
+    def test_quality_floors_at_zero(self):
+        item = Item("Conjured Mana Cake", sell_in=5, quality=1)
+        self.strategy.update(item, days=1)
+        self.assertEqual(0, item.quality)
+
+    def test_quality_degrades_by_4_after_sell_date(self):
+        # Past sell date: -4 per day
+        item = Item("Conjured Mana Cake", sell_in=0, quality=20)
+        self.strategy.update(item, days=1)
+        self.assertEqual(16, item.quality)
+        self.assertEqual(-1, item.sell_in)
+
+    def test_multi_day_crosses_sell_date(self):
+        # sell_in=1, quality=10, days=3
+        # Day1: q=8 si=0 | Day2: q=4 si=-1 | Day3: q=0 si=-2
+        item = Item("Conjured Mana Cake", sell_in=1, quality=10)
+        self.strategy.update(item, days=3)
+        self.assertEqual(0, item.quality)
+        self.assertEqual(-2, item.sell_in)
+
+    def test_quality_floors_at_zero_post_sell_date(self):
+        item = Item("Conjured Mana Cake", sell_in=0, quality=2)
+        self.strategy.update(item, days=1)
+        self.assertEqual(0, item.quality)
+
+
 if __name__ == '__main__':
     unittest.main()