Possible GildedRose C# Test Solutions

GildedRoseTest.cs

using Xunit;

namespace KataGildedRose.Tests
{
    public class GildedRoseTest
    {
		private const string BackstageName = "Backstage passes to a TAFKAL80ETC concert";
		private const string NormalItemName = "foo";
		private const string AgedBrieName = "Aged Brie";
		private const string SulfurasName = "Sulfuras, Hand of Ragnaros";
	
		private const int QualityChange = 1;
		private const int NormalItemQuality = 5;
		private const int MinimumQuality = 0;
		private const int MaximumQuality = 50;
	
		private const int SellInChange = 1;
		private const int ExpiredSellIn = 0;
		private const int NormalItemSellIn = 15;
		private const int SellInIn5Days = 5;
		private const int SellInIn10Days = 10;
	
		[Fact]
		public void SellIn_DecreasesEveryDay() {
			VerifySellIn(NormalItemSellIn - SellInChange, NormalItem());
		}
	
		[Fact]
		public void Quality_DecreasesEveryDay() {
			VerifyQuality(NormalItemQuality - QualityChange, NormalItem());
		}
	
		[Fact]
		public void Quality_DecreasesTwiceAsFast_OnceSellInHasPassed() {
			VerifyQuality(NormalItemQuality - 2 * QualityChange, ExpiredItem());
		}
	
		[Fact]
		public void Quality_IsNeverNegative() {
			VerifyQuality(MinimumQuality, ItemWithoutQuality());
		}
	
		[Fact]
		public void AgedBrie_IncreasesQuality() {
			VerifyQuality(NormalItemQuality + QualityChange, AgedBrie());
		}
	
		[Fact]
		public void Item_NeverIncreaseQuality_WhenHasReachedTheMaximum() {
			VerifyQuality(MaximumQuality, AgedBrieWithMaximumQuality());
		}
	
		[Fact]
		public void Sulfuras_NeverChanges_TheQuality() {
			VerifyQuality(NormalItemQuality, Sulfuras());
		}
	
		[Fact]
		public void Sulfuras_NeverChanges_TheSellIn() {
			VerifySellIn(NormalItemSellIn, Sulfuras());
		}
	
		[Fact]
		public void Backstage_IncreaseQuality() {
			VerifyQuality(NormalItemQuality + QualityChange, Backstage());
		}
	
		[Fact]
		public void Backstage_IncreaseQualityBy2_WhenSellInIs10OrLess() {
			VerifyQuality(NormalItemQuality + 2 * QualityChange, BackstageIn10Days());
		}
	
		[Fact]
		public void Backstage_IncreaseQualityBy3_WhenSellInIs5OrLess() {
			VerifyQuality(NormalItemQuality + 3 * QualityChange, BackstageIn5Days());
		}
	
		[Fact]
		public void Backstage_DropsTo0Quality_AfterTheConcert() {
			VerifyQuality(MinimumQuality, BackstageAfterTheConcert());
		}
	
		[Fact]
		public void AgedBrie_ExpiredGetsTheMaximumQuality_WhenHasOneLessThanMaximumQuality() {
			Item item = new Item
			{
				Name = AgedBrieName, 
				SellIn = ExpiredSellIn,
				Quality = MaximumQuality - 1
			};
			VerifyQuality(MaximumQuality, item);
		}
	
		private void VerifySellIn(int expectedSellIn, Item item) {
			GildedRose gildedRose = GildedRose(item);
			gildedRose.UpdateQuality();
			AssertSellIn(expectedSellIn, gildedRose);
		}
	
		private void VerifyQuality(int expectedQuality, Item normalItem) {
			GildedRose gildedRose = GildedRose(normalItem);
			gildedRose.UpdateQuality();
			assertQuality(expectedQuality, gildedRose);
		}
	
		private GildedRose GildedRose(Item item) {
			Item[] items = new Item[] { item };
			GildedRose app = new GildedRose(items);
			return app;
		}
	
		private Item NormalItem() {
			return ItemWithNormalSellInAndQuality(NormalItemName);
		}
	
		private Item ExpiredItem() {
			return ItemWithNormalQuality(NormalItemName, ExpiredSellIn);
		}
	
		private Item ItemWithoutQuality() {
			return new Item
			{
				Name = NormalItemName, 
				SellIn = NormalItemSellIn, 
				Quality = MinimumQuality
			};
		}
	
		private Item AgedBrie() {
			return ItemWithNormalSellInAndQuality(AgedBrieName);
		}
	
		private Item AgedBrieWithMaximumQuality() {
			return new Item
				{
					Name = AgedBrieName, 
					SellIn = NormalItemSellIn, 
					Quality = MaximumQuality
				};
		}
	
		private Item Sulfuras() {
			return ItemWithNormalSellInAndQuality(SulfurasName);
		}
	
		private Item Backstage() {
			return ItemWithNormalSellInAndQuality(BackstageName);
		}
	
		private Item BackstageIn10Days() {
			return ItemWithNormalQuality(BackstageName, SellInIn10Days);
		}
	
		private Item BackstageIn5Days() {
			return ItemWithNormalQuality(BackstageName, SellInIn5Days);
		}
	
		private Item BackstageAfterTheConcert() {
			return ItemWithNormalQuality(BackstageName, ExpiredSellIn);
		}
	
		private Item ItemWithNormalSellInAndQuality(string name) {
			return ItemWithNormalQuality(name, NormalItemSellIn);
		}
	
		private Item ItemWithNormalQuality(string name, int sellIn) {
			return new Item {
				Name = name, 
				SellIn = sellIn, 
				Quality = NormalItemQuality
			};
		}
	
		private void AssertSellIn(int expectedSellIn, GildedRose gildedRose) {
			Assert.Equal(expectedSellIn, gildedRose.Items[0].SellIn);
		}
	
		private void assertQuality(int expectedQuality, GildedRose gildedRose) {
			Assert.Equal(expectedQuality, gildedRose.Items[0].Quality);
		}
    }
}