Adding Unittests to ensure logic of the code is correct

csharpcore/GildedRoseTest.cs

@@ -6,12 +6,142 @@ namespace csharpcore
     public class GildedRoseTest
     {
         [Fact]
-        public void foo()
+        public void UpdateQuality_NoItems_YieldNoException()
         {
-            IList<Item> Items = new List<Item> { new Item { Name = "foo", SellIn = 0, Quality = 0 } };
-            GildedRose app = new GildedRose(Items);
+            IList<Item> items = new List<Item> { };
+            GildedRose app = new GildedRose(items);
+
             app.UpdateQuality();
-            Assert.Equal("fixme", Items[0].Name);
+        }
+
+        [Fact]
+        public void UpdateQuality_SulfuraItem_Unchanged()
+        {
+            IList<Item> items = new List<Item> { new Item { Name = "Sulfuras, Hand of Ragnaros", SellIn = 10, Quality = 80 } };
+            GildedRose app = new GildedRose(items);
+
+            app.UpdateQuality();
+
+            Assert.Equal(80, items[0].Quality);
+            Assert.Equal(10, items[0].SellIn);
+        }
+
+        [Theory]
+        [InlineData(7, 7, 8)]
+        [InlineData(0, 7, 8)] // Issue with Aged Brie that increase Quality twice as fast after SellIn, correct ?
+        public void UpdateQuality_AgedBrie_QualityIncreases(int beforeSellIn, int beforeQuality, int afterQuality)
+        {
+            IList<Item> items = new List<Item> { new Item { Name = "Aged Brie", SellIn = beforeSellIn, Quality = beforeQuality } };
+            GildedRose app = new GildedRose(items);
+
+            app.UpdateQuality();
+
+            Assert.Equal(afterQuality, items[0].Quality);
+            Assert.Equal(beforeSellIn - 1, items[0].SellIn);
+        }
+
+        [Theory]
+        [InlineData(7, 50, 50)]
+        [InlineData(0, 50, 50)]
+        public void UpdateQuality_AgedBrieMaxQuality_QualityToppedAtFifty(int beforeSellIn, int beforeQuality, int afterQuality)
+        {
+            IList<Item> items = new List<Item> { new Item { Name = "Aged Brie", SellIn = beforeSellIn, Quality = beforeQuality } };
+            GildedRose app = new GildedRose(items);
+
+            app.UpdateQuality();
+
+            Assert.Equal(afterQuality, items[0].Quality);
+            Assert.Equal(beforeSellIn - 1, items[0].SellIn);
+        }
+
+        [Theory]
+        [InlineData(11, 7, 8)]
+        [InlineData(10, 7, 9)]
+        [InlineData(5, 7, 10)]
+        public void UpdateQuality_BackStagePass_QualityIncreases(int beforeSellIn, int beforeQuality, int afterQuality)
+        {
+            IList<Item> items = new List<Item> { 
+                new Item { 
+                    Name = "Backstage passes to a TAFKAL80ETC concert", 
+                    SellIn = beforeSellIn, 
+                    Quality = beforeQuality 
+                } 
+            };
+            GildedRose app = new GildedRose(items);
+
+            app.UpdateQuality();
+
+            Assert.Equal(afterQuality, items[0].Quality);
+            Assert.Equal(beforeSellIn-1, items[0].SellIn);
+        }
+
+        [Theory]
+        [InlineData(0, 7, 0)]
+        [InlineData(0, 50, 0)]
+        public void UpdateQuality_BackStagePassAfterConcert_QualityZeroed(int beforeSellIn, int beforeQuality, int afterQuality)
+        {
+            IList<Item> items = new List<Item> {
+                new Item {
+                    Name = "Backstage passes to a TAFKAL80ETC concert",
+                    SellIn = beforeSellIn,
+                    Quality = beforeQuality
+                }
+            };
+            GildedRose app = new GildedRose(items);
+
+            app.UpdateQuality();
+
+            Assert.Equal(afterQuality, items[0].Quality);
+            Assert.Equal(beforeSellIn - 1, items[0].SellIn);
+        }
+
+        [Theory]
+        [InlineData(11, 50, 50)]
+        [InlineData(10, 50, 50)]
+        [InlineData(5, 50, 50)]
+        public void UpdateQuality_BackStagePassMaxQuality_QualityToppedAtFifty(int beforeSellIn, int beforeQuality, int afterQuality)
+        {
+            IList<Item> items = new List<Item> {
+                new Item {
+                    Name = "Backstage passes to a TAFKAL80ETC concert",
+                    SellIn = beforeSellIn,
+                    Quality = beforeQuality
+                }
+            };
+            GildedRose app = new GildedRose(items);
+
+            app.UpdateQuality();
+
+            Assert.Equal(afterQuality, items[0].Quality);
+            Assert.Equal(beforeSellIn - 1, items[0].SellIn);
+        }
+
+        [Theory]
+        [InlineData(7, 10, 9)]
+        [InlineData(0, 10, 8)]
+        public void UpdateQuality_MiscelaniousItem_QualityDecreases(int beforeSellIn, int beforeQuality, int afterQuality)
+        {
+            IList<Item> items = new List<Item> { new Item { Name = "Wooden Sword", SellIn = beforeSellIn, Quality = beforeQuality } };
+            GildedRose app = new GildedRose(items);
+
+            app.UpdateQuality();
+
+            Assert.Equal(afterQuality, items[0].Quality);
+            Assert.Equal(beforeSellIn - 1, items[0].SellIn);
+        }
+
+        [Theory]
+        [InlineData(7, 0, 0)]
+        [InlineData(0, 0, 0)]
+        public void UpdateQuality_MiscelaniousItemMinQuality_QualityCannotGoNegative(int beforeSellIn, int beforeQuality, int afterQuality)
+        {
+            IList<Item> items = new List<Item> { new Item { Name = "Leeroy Jenkins Trinket", SellIn = beforeSellIn, Quality = beforeQuality } };
+            GildedRose app = new GildedRose(items);
+
+            app.UpdateQuality();
+
+            Assert.Equal(afterQuality, items[0].Quality);
+            Assert.Equal(beforeSellIn - 1, items[0].SellIn);
         }
     }
 }