diff --git a/csharpcore/GildedRose/GildedRose.cs b/csharpcore/GildedRose/GildedRose.cs
index ed7dc428..e89e88c2 100644
--- a/csharpcore/GildedRose/GildedRose.cs
+++ b/csharpcore/GildedRose/GildedRose.cs
@@ -5,6 +5,7 @@ namespace GildedRoseKata
     public class GildedRose
     {
         IList<Item> Items;
+
         public GildedRose(IList<Item> Items)
         {
             this.Items = Items;
@@ -14,72 +15,76 @@ 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")
+                int qualityModifier = Items[i].Name.StartsWith("Conjured") ? 2 : 1;
                 {
-                    if (Items[i].Quality > 0)
+                    if (Items[i].Name != "Aged Brie" && Items[i].Name != "Backstage passes to a TAFKAL80ETC concert")
                     {
-                        if (Items[i].Name != "Sulfuras, Hand of Ragnaros")
+                        if (Items[i].Quality > 0)
                         {
-                            Items[i].Quality = Items[i].Quality - 1;
-                        }
-                    }
-                }
-                else
-                {
-                    if (Items[i].Quality < 50)
-                    {
-                        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].Name != "Sulfuras, Hand of Ragnaros")
                             {
-                                if (Items[i].Quality < 50)
-                                {
-                                    Items[i].Quality = Items[i].Quality + 1;
-                                }
+                                Items[i].Quality -= qualityModifier;
                             }
-
-                            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;
+                            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 += qualityModifier;
+                                    }
+                                }
+
+                                if (Items[i].SellIn < 6)
+                                {
+                                    if (Items[i].Quality < 50)
+                                    {
+                                        Items[i].Quality += qualityModifier;
+                                    }
+                                }
+                            }
+                        }
+                    }
+
+                    if (Items[i].Name != "Sulfuras, Hand of Ragnaros")
+                    {
+                        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 -= qualityModifier;
+
+                                    }
+                                }
+                            }
+                            else
+                            {
+                                Items[i].Quality = 0;
+                            }
+                        }
+                        else
+                        {
+                            if (Items[i].Quality < 50)
+                            {
+                                Items[i].Quality += qualityModifier;
+                            }
                         }
                     }
                 }
@@ -87,3 +92,4 @@ namespace GildedRoseKata
         }
     }
 }
+
diff --git a/csharpcore/GildedRoseTests/GildedRoseTest.cs b/csharpcore/GildedRoseTests/GildedRoseTest.cs
index 6e5d24b6..3aedee62 100644
--- a/csharpcore/GildedRoseTests/GildedRoseTest.cs
+++ b/csharpcore/GildedRoseTests/GildedRoseTest.cs
@@ -1,18 +1,148 @@
-using Xunit;
+using NUnit;
 using System.Collections.Generic;
+using System.Linq;
 using GildedRoseKata;
+using NUnit.Framework;
 
 namespace GildedRoseTests
 {
-    public class GildedRoseTest
+    [TestFixture]
+    public class GildedRoseUpdateQuality
     {
-        [Fact]
-        public void foo()
+        [SetUp]
+        public void Setup()
         {
-            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);
         }
+
+        private List<Item> ResetItems()
+        {
+            return new List<Item>
+            {
+                new Item { Name = "+5 Dexterity Vest", SellIn = 10, Quality = 20 },
+                new Item { 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 Item { Name = "Sulfuras, Hand of Ragnaros", SellIn = -1, Quality = 80 },
+                new Item
+                {
+                    Name = "Backstage passes to a TAFKAL80ETC concert",
+                    SellIn = 15,
+                    Quality = 20
+                },
+                new Item
+                {
+                    Name = "Backstage passes to a TAFKAL80ETC concert",
+                    SellIn = 10,
+                    Quality = 49
+                },
+                new Item
+                {
+                    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 }
+            };
+        }
+
+        [TestCase("Sulfuras, Hand of Ragnaros", 10, 80, 80)]
+        [TestCase("Elixir of the Mongoose", 10, 7, 6)]
+        [TestCase("Aged Brie", 10, 0, 1)]
+        [TestCase("Backstage passes to a TAFKAL80ETC concert",15,10,11)]
+        [TestCase("Backstage passes to a TAFKAL80ETC concert",10,10,12)]
+        [TestCase("Backstage passes to a TAFKAL80ETC concert",5,10,13)]
+        [TestCase("Backstage passes to a TAFKAL80ETC concert",0,10,0)]
+        [TestCase("Conjured Mana Cake", 10,10,8)]
+        public void ShouldUpdateQuality_BeforeSellByDate(string name, int sellInDays, int startQuality, int endQuality)
+        {
+            //Arrange
+            var item = new Item
+            {
+                Name = name,
+                Quality = startQuality,
+                SellIn = sellInDays
+            };
+            var items = new List<Item>() { item };
+            var app = new GildedRose(items);
+            //Act
+            app.UpdateQuality();
+            //Assert
+            var updatedItem = items.FirstOrDefault(x => x.Name == name);
+            Assert.NotNull(updatedItem);
+            Assert.AreEqual(endQuality, updatedItem.Quality);
+        }
+
+        [TestCase("Sulfuras, Hand of Ragnaros", 0, 80, 80)]
+        [TestCase("Elixir of the Mongoose", 0, 7, 5)]
+        [TestCase("Aged Brie", 0, 0, 2)]
+        [TestCase("Conjured Mana Cake", 0, 10, 6)]
+        public void ShouldUpdateQualityDifferently_AfterSellByDate(string name, int sellInDays, int startQuality, int endQuality)
+        {
+            //Arrange
+            var item = new Item
+            {
+                Name = name,
+                Quality = startQuality,
+                SellIn = sellInDays
+            };
+            var items = new List<Item>() { item };
+            var app = new GildedRose(items);
+            //Act
+            app.UpdateQuality();
+            //Assert
+            var updatedItem = items.FirstOrDefault();
+            Assert.NotNull(updatedItem);
+            Assert.AreEqual(endQuality, updatedItem.Quality);
+        }
+
+        [TestCase("Sulfuras, Hand of Ragnaros", 80)]
+        [TestCase("Elixir of the Mongoose", 0)]
+        [TestCase("Aged Brie", 0)]
+        [TestCase("Conjured Mana Cake", 0)]
+        public void ShouldNotAllowNegativeQuality(string name, int startQuality)
+        {
+            //Arrange
+            var item = new Item
+            {
+                Name = name,
+                Quality = startQuality,
+                SellIn = 10
+            };
+            var items = new List<Item>() { item };
+            var app = new GildedRose(items);
+            //Act
+            app.UpdateQuality();
+            
+            //Assert
+            var updatedItem = items.FirstOrDefault();
+            Assert.GreaterOrEqual(item.Quality, 0);
+        }
+        [TestCase("Sulfuras, Hand of Ragnaros", 80)]
+        [TestCase("Elixir of the Mongoose")]
+        [TestCase("Aged Brie")]
+        [TestCase("Conjured Mana Cake")]
+
+        public void ShouldNotExceedMaximumQuality(string name, int maxQuality=50)
+        {
+            //Arrange
+            var item = new Item
+            {
+                Name = name,
+                Quality = maxQuality,
+                SellIn = 10
+            };
+            var items = new List<Item>() { item };
+            var app = new GildedRose(items);
+            //Act
+            app.UpdateQuality();
+
+            //Assert
+            var updatedItem = items.FirstOrDefault();
+            Assert.LessOrEqual(item.Quality, maxQuality);
+        }
+
+
+
     }
-}
+}
\ No newline at end of file
diff --git a/csharpcore/GildedRoseTests/GildedRoseTests.csproj b/csharpcore/GildedRoseTests/GildedRoseTests.csproj
index 93a44263..19c36680 100644
--- a/csharpcore/GildedRoseTests/GildedRoseTests.csproj
+++ b/csharpcore/GildedRoseTests/GildedRoseTests.csproj
@@ -8,6 +8,7 @@
 
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.0.0" />
+        <PackageReference Include="NUnit" Version="3.13.3" />
         <PackageReference Include="xunit" Version="2.4.1" />
         <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" />
         <PackageReference Include="coverlet.collector" Version="3.1.0" />