- add unit tests to legacy code for each business rule

- refactor the UpdateQuality method by :
* removing all static item names
* strongly typing the different items
* moving specific business logic inside the business object

csharpcore-Verify.xunit/GildedRose/AgingItem.cs

@@ -0,0 +1,21 @@
+namespace GildedRoseKata
+{
+    public class AgingItem : Item
+    {
+
+        public virtual void SetAgingItemQuality()
+        {
+            if (Quality < 50)
+            {
+                Quality++;
+
+                SellIn--;
+
+                if (SellIn < 0 && Quality < 50)
+                {
+                    Quality++;
+                }
+            }
+        }
+    }
+}

csharpcore-Verify.xunit/GildedRose/ConcertPass.cs

@@ -0,0 +1,31 @@
+using GildedRoseKata;
+
+namespace GildedRoseKata
+{
+    public class ConcertPass : AgingItem
+    {
+        public override void SetAgingItemQuality()
+        {
+            if (Quality < 50)
+            {
+                Quality++;
+
+                if (SellIn < 11 && Quality < 50)
+                {
+                    Quality++;
+                }
+
+                if (SellIn < 6 && Quality < 50)
+                {
+                    Quality++;
+                }
+
+                SellIn--;
+                if (SellIn < 0)
+                {
+                    Quality = 0;
+                }
+            }
+        }
+    }
+}

csharpcore-Verify.xunit/GildedRose/ConjuredItem.cs

@@ -0,0 +1,6 @@
+namespace GildedRoseKata
+{
+    public class ConjuredItem : Item
+    {
+    }
+}

csharpcore-Verify.xunit/GildedRose/GildedRose.cs

@@ -4,7 +4,7 @@ namespace GildedRoseKata
 {
     public class GildedRose
     {
-        IList<Item> Items;
+        private readonly IList<Item> Items;
         public GildedRose(IList<Item> Items)
         {
             this.Items = Items;
@@ -14,76 +14,45 @@ namespace GildedRoseKata
         {
             for (var i = 0; i < Items.Count; i++)
             {
-                if (Items[i].Name != "Aged Brie" && Items[i].Name != "Backstage passes to a TAFKAL80ETC concert")
+                switch (Items[i])
                 {
-                    if (Items[i].Quality > 0)
+                    case LegendaryItem l: break;
-                    {
+                    case AgingItem a:
-                        if (Items[i].Name != "Sulfuras, Hand of Ragnaros")
+                        a.SetAgingItemQuality();
-                        {
+                        break;
-                            Items[i].Quality = Items[i].Quality - 1;
+                    case ConjuredItem c:
-                        }
+                        DecreaseItemProperties(c);
-                    }
+                        DecreaseItemQuality(c);
-                }
+                        break;
-                else
+                    default:
-                {
+                        DecreaseItemProperties(Items[i]);
-                    if (Items[i].Quality < 50)
+                        break;
-                    {
-                        Items[i].Quality = Items[i].Quality + 1;
-
-                        if (Items[i].Name == "Backstage passes to a TAFKAL80ETC concert")
-                        {
-                            if (Items[i].SellIn < 11)
-                            {
-                                if (Items[i].Quality < 50)
-                                {
-                                    Items[i].Quality = Items[i].Quality + 1;
-                                }
-                            }
-
-                            if (Items[i].SellIn < 6)
-                            {
-                                if (Items[i].Quality < 50)
-                                {
-                                    Items[i].Quality = Items[i].Quality + 1;
-                                }
-                            }
-                        }
-                    }
-                }
-
-                if (Items[i].Name != "Sulfuras, Hand of Ragnaros")
-                {
-                    Items[i].SellIn = Items[i].SellIn - 1;
-                }
-
-                if (Items[i].SellIn < 0)
-                {
-                    if (Items[i].Name != "Aged Brie")
-                    {
-                        if (Items[i].Name != "Backstage passes to a TAFKAL80ETC concert")
-                        {
-                            if (Items[i].Quality > 0)
-                            {
-                                if (Items[i].Name != "Sulfuras, Hand of Ragnaros")
-                                {
-                                    Items[i].Quality = Items[i].Quality - 1;
-                                }
-                            }
-                        }
-                        else
-                        {
-                            Items[i].Quality = Items[i].Quality - Items[i].Quality;
-                        }
-                    }
-                    else
-                    {
-                        if (Items[i].Quality < 50)
-                        {
-                            Items[i].Quality = Items[i].Quality + 1;
-                        }
-                    }
                 }
             }
         }
+
+        private void DecreaseItemProperties(Item item)
+        {
+            DecreaseItemQuality(item);
+            DecreateItemSellIn(item);
+            DecreaseItemQuality(item);
+        }
+
+        private void DecreaseItemQuality(Item item)
+        {
+            if (item.Quality > 0)
+            {
+                item.Quality--;
+            }
+        }
+
+        private void DecreateItemSellIn(Item item)
+        {
+            if (item is not LegendaryItem)
+            {
+                item.SellIn--;
+            }
+        }
+        
     }
 }

csharpcore-Verify.xunit/GildedRose/LegendaryItem.cs

@@ -0,0 +1,6 @@
+namespace GildedRoseKata
+{
+    public class LegendaryItem : Item
+    {
+    }
+}

csharpcore-Verify.xunit/GildedRose/Program.cs

@@ -11,30 +11,30 @@ namespace GildedRoseKata
 
             IList<Item> Items = new List<Item>{
                 new Item {Name = "+5 Dexterity Vest", SellIn = 10, Quality = 20},
-                new Item {Name = "Aged Brie", SellIn = 2, Quality = 0},
+                new AgingItem {Name = "Aged Brie", SellIn = 2, Quality = 0},
                 new Item {Name = "Elixir of the Mongoose", SellIn = 5, Quality = 7},
-                new Item {Name = "Sulfuras, Hand of Ragnaros", SellIn = 0, Quality = 80},
+                new LegendaryItem {Name = "Sulfuras, Hand of Ragnaros", SellIn = 0, Quality = 80},
-                new Item {Name = "Sulfuras, Hand of Ragnaros", SellIn = -1, Quality = 80},
+                new LegendaryItem {Name = "Sulfuras, Hand of Ragnaros", SellIn = -1, Quality = 80},
-                new Item
+                new ConcertPass
                 {
                     Name = "Backstage passes to a TAFKAL80ETC concert",
                     SellIn = 15,
                     Quality = 20
                 },
-                new Item
+                new ConcertPass
                 {
                     Name = "Backstage passes to a TAFKAL80ETC concert",
                     SellIn = 10,
                     Quality = 49
                 },
-                new Item
+                new ConcertPass
                 {
                     Name = "Backstage passes to a TAFKAL80ETC concert",
                     SellIn = 5,
                     Quality = 49
                 },
 				// this conjured item does not work properly yet
-				new Item {Name = "Conjured Mana Cake", SellIn = 3, Quality = 6}
+				new ConjuredItem {Name = "Conjured Mana Cake", SellIn = 3, Quality = 6}
             };
 
             var app = new GildedRose(Items);

csharpcore-Verify.xunit/GildedRoseTests/ApprovalTest.ThirtyDays.received.txt

@@ -0,0 +1,373 @@
+OMGHAI!
+-------- day 0 --------
+name, sellIn, quality
++5 Dexterity Vest, 10, 20
+Aged Brie, 2, 0
+Elixir of the Mongoose, 5, 7
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 15, 20
+Backstage passes to a TAFKAL80ETC concert, 10, 49
+Backstage passes to a TAFKAL80ETC concert, 5, 49
+Conjured Mana Cake, 3, 6
+
+-------- day 1 --------
+name, sellIn, quality
++5 Dexterity Vest, 9, 18
+Aged Brie, 1, 1
+Elixir of the Mongoose, 4, 5
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 14, 21
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, 2, 3
+
+-------- day 2 --------
+name, sellIn, quality
++5 Dexterity Vest, 8, 16
+Aged Brie, 0, 2
+Elixir of the Mongoose, 3, 3
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 13, 22
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, 1, 0
+
+-------- day 3 --------
+name, sellIn, quality
++5 Dexterity Vest, 7, 14
+Aged Brie, -1, 4
+Elixir of the Mongoose, 2, 1
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 12, 23
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, 0, 0
+
+-------- day 4 --------
+name, sellIn, quality
++5 Dexterity Vest, 6, 12
+Aged Brie, -2, 6
+Elixir of the Mongoose, 1, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 11, 24
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -1, 0
+
+-------- day 5 --------
+name, sellIn, quality
++5 Dexterity Vest, 5, 10
+Aged Brie, -3, 8
+Elixir of the Mongoose, 0, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 10, 25
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -2, 0
+
+-------- day 6 --------
+name, sellIn, quality
++5 Dexterity Vest, 4, 8
+Aged Brie, -4, 10
+Elixir of the Mongoose, -1, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 9, 27
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -3, 0
+
+-------- day 7 --------
+name, sellIn, quality
++5 Dexterity Vest, 3, 6
+Aged Brie, -5, 12
+Elixir of the Mongoose, -2, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 8, 29
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -4, 0
+
+-------- day 8 --------
+name, sellIn, quality
++5 Dexterity Vest, 2, 4
+Aged Brie, -6, 14
+Elixir of the Mongoose, -3, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 7, 31
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -5, 0
+
+-------- day 9 --------
+name, sellIn, quality
++5 Dexterity Vest, 1, 2
+Aged Brie, -7, 16
+Elixir of the Mongoose, -4, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 6, 33
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -6, 0
+
+-------- day 10 --------
+name, sellIn, quality
++5 Dexterity Vest, 0, 0
+Aged Brie, -8, 18
+Elixir of the Mongoose, -5, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 5, 35
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -7, 0
+
+-------- day 11 --------
+name, sellIn, quality
++5 Dexterity Vest, -1, 0
+Aged Brie, -9, 20
+Elixir of the Mongoose, -6, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 4, 38
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -8, 0
+
+-------- day 12 --------
+name, sellIn, quality
++5 Dexterity Vest, -2, 0
+Aged Brie, -10, 22
+Elixir of the Mongoose, -7, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 3, 41
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -9, 0
+
+-------- day 13 --------
+name, sellIn, quality
++5 Dexterity Vest, -3, 0
+Aged Brie, -11, 24
+Elixir of the Mongoose, -8, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 2, 44
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -10, 0
+
+-------- day 14 --------
+name, sellIn, quality
++5 Dexterity Vest, -4, 0
+Aged Brie, -12, 26
+Elixir of the Mongoose, -9, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 1, 47
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -11, 0
+
+-------- day 15 --------
+name, sellIn, quality
++5 Dexterity Vest, -5, 0
+Aged Brie, -13, 28
+Elixir of the Mongoose, -10, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -12, 0
+
+-------- day 16 --------
+name, sellIn, quality
++5 Dexterity Vest, -6, 0
+Aged Brie, -14, 30
+Elixir of the Mongoose, -11, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -13, 0
+
+-------- day 17 --------
+name, sellIn, quality
++5 Dexterity Vest, -7, 0
+Aged Brie, -15, 32
+Elixir of the Mongoose, -12, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -14, 0
+
+-------- day 18 --------
+name, sellIn, quality
++5 Dexterity Vest, -8, 0
+Aged Brie, -16, 34
+Elixir of the Mongoose, -13, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -15, 0
+
+-------- day 19 --------
+name, sellIn, quality
++5 Dexterity Vest, -9, 0
+Aged Brie, -17, 36
+Elixir of the Mongoose, -14, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -16, 0
+
+-------- day 20 --------
+name, sellIn, quality
++5 Dexterity Vest, -10, 0
+Aged Brie, -18, 38
+Elixir of the Mongoose, -15, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -17, 0
+
+-------- day 21 --------
+name, sellIn, quality
++5 Dexterity Vest, -11, 0
+Aged Brie, -19, 40
+Elixir of the Mongoose, -16, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -18, 0
+
+-------- day 22 --------
+name, sellIn, quality
++5 Dexterity Vest, -12, 0
+Aged Brie, -20, 42
+Elixir of the Mongoose, -17, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -19, 0
+
+-------- day 23 --------
+name, sellIn, quality
++5 Dexterity Vest, -13, 0
+Aged Brie, -21, 44
+Elixir of the Mongoose, -18, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -20, 0
+
+-------- day 24 --------
+name, sellIn, quality
++5 Dexterity Vest, -14, 0
+Aged Brie, -22, 46
+Elixir of the Mongoose, -19, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -21, 0
+
+-------- day 25 --------
+name, sellIn, quality
++5 Dexterity Vest, -15, 0
+Aged Brie, -23, 48
+Elixir of the Mongoose, -20, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -22, 0
+
+-------- day 26 --------
+name, sellIn, quality
++5 Dexterity Vest, -16, 0
+Aged Brie, -24, 50
+Elixir of the Mongoose, -21, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -23, 0
+
+-------- day 27 --------
+name, sellIn, quality
++5 Dexterity Vest, -17, 0
+Aged Brie, -24, 50
+Elixir of the Mongoose, -22, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -24, 0
+
+-------- day 28 --------
+name, sellIn, quality
++5 Dexterity Vest, -18, 0
+Aged Brie, -24, 50
+Elixir of the Mongoose, -23, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -25, 0
+
+-------- day 29 --------
+name, sellIn, quality
++5 Dexterity Vest, -19, 0
+Aged Brie, -24, 50
+Elixir of the Mongoose, -24, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -26, 0
+
+-------- day 30 --------
+name, sellIn, quality
++5 Dexterity Vest, -20, 0
+Aged Brie, -24, 50
+Elixir of the Mongoose, -25, 0
+Sulfuras, Hand of Ragnaros, 0, 80
+Sulfuras, Hand of Ragnaros, -1, 80
+Backstage passes to a TAFKAL80ETC concert, 0, 50
+Backstage passes to a TAFKAL80ETC concert, 9, 50
+Backstage passes to a TAFKAL80ETC concert, 4, 50
+Conjured Mana Cake, -27, 0
+

csharpcore-Verify.xunit/GildedRoseTests/ApprovalTest.ThirtyDays.verified.txt

@@ -0,0 +1 @@
+

csharpcore-Verify.xunit/GildedRoseTests/GildedRoseTest.cs

@@ -12,7 +12,82 @@ namespace GildedRoseTests
             IList<Item> Items = new List<Item> { new Item { Name = "foo", SellIn = 0, Quality = 0 } };
             GildedRose app = new GildedRose(Items);
             app.UpdateQuality();
-            Assert.Equal("fixme", Items[0].Name);
+            Assert.Equal("foo", Items[0].Name);
         }
+        //Once the sell by date has passed, Quality degrades twice as fast
+        [Fact]
+        public void UpdateQuality_Should_Return_ExpiredItem_Quality4_Become_Quality2()
+        {
+            IList<Item> Items = new List<Item> { new Item { Name = "BigStuff", SellIn = -1, Quality = 4 } };
+            GildedRose app = new GildedRose(Items);
+            app.UpdateQuality();
+            Assert.Equal(2,Items[0].Quality);
+        }
+        //The Quality of an item is never negative
+        [Fact]
+        public void UpdateQuality_Should_Return_Item_Quality_Never_Negative()
+        {
+            IList<Item> Items = new List<Item> { new Item { Name = "BigStuff", SellIn = 1, Quality = 0 } };
+            GildedRose app = new GildedRose(Items);
+            app.UpdateQuality();
+            Assert.False(Items[0].Quality < 0);
+        }
+        //“Aged Brie” actually increases in Quality the older it gets
+        [Fact]
+        public void UpdateQuality_Should_Return_AgedBrie_Quality1()
+        {
+            IList<Item> Items = new List<Item> { new AgingItem { Name = "Aged Brie", SellIn = 2, Quality = 0 } };
+            GildedRose app = new GildedRose(Items);
+            app.UpdateQuality();
+            Assert.Equal(1, Items[0].Quality);
+        }
+        //“Sulfuras”, being a legendary item, never has to be sold or decreases in Quality
+        [Fact]
+        public void UpdateQuality_Should_Return_LegendaryItem_Unchanged()
+        {
+            IList<Item> Items = new List<Item> { new LegendaryItem { Name = "Sulfuras, Hand of Ragnaros", SellIn = 0, Quality = 80 } };
+            GildedRose app = new GildedRose(Items);
+            app.UpdateQuality();
+            Assert.Equal(80, Items[0].Quality);
+            Assert.Equal(0, Items[0].SellIn);
+        }
+        //“Backstage passes” Quality increases by 2 when there are 10 days or less
+        [Fact]
+        public void UpdateQuality_Should_Return_Passes_IncreasesBy2_When_SellinLessThen10()
+        {
+            IList<Item> Items = new List<Item> { new ConcertPass { Name = "Backstage passes to a TAFKAL80ETC concert", SellIn = 9, Quality = 20 } };
+            GildedRose app = new GildedRose(Items);
+            app.UpdateQuality();
+            Assert.Equal(22, Items[0].Quality);
+        }
+        //“Backstage passes” Quality increases by 3 when there are 5 days or less
+        [Fact]
+        public void UpdateQuality_Should_Return_Passes_IncreasesBy3_When_SellinLessThen5()
+        {
+            IList<Item> Items = new List<Item> { new ConcertPass { Name = "Backstage passes to a TAFKAL80ETC concert", SellIn = 4, Quality = 20 } };
+            GildedRose app = new GildedRose(Items);
+            app.UpdateQuality();
+            Assert.Equal(23, Items[0].Quality);
+        }
+        //“Backstage passes” Quality drops to 0 after the concert
+        [Fact]
+        public void UpdateQuality_Should_Return_PassesQuality0_When_Sellin_LessThan0()
+        {
+            IList<Item> Items = new List<Item> { new ConcertPass { Name = "Backstage passes to a TAFKAL80ETC concert", SellIn = -1, Quality = 20 } };
+            GildedRose app = new GildedRose(Items);
+            app.UpdateQuality();
+            Assert.Equal(0, Items[0].Quality);
+        }
+        //“Conjured” items degrade in Quality twice as fast as normal items
+        [Fact]
+        public void UpdateQuality_Should_Return_ConjuredQuality0_When_Quality2()
+        {
+            IList<Item> Items = new List<Item> { new ConjuredItem { Name = "Conjured Mana Cake", SellIn = 3, Quality = 2 } };
+            GildedRose app = new GildedRose(Items);
+            app.UpdateQuality();
+            Assert.Equal(0, Items[0].Quality);
+        }
+
+
     }
 }