implement conjured item

TypeScript/app/gilded-rose.ts

@@ -40,13 +40,15 @@ export class GildedRose {
   private _isBackstagePass = (name: string): boolean =>
     name === "Backstage passes to a TAFKAL80ETC concert";
 
+  private _isConjured = (name: string): boolean => name.includes("Conjured");
+
   private _decayGeneralItem = (item: Item): Item => {
-    const qualityDecay = item.sellIn > 0 ? 1 : 2;
-    return {
+    const newItem = {
       name: item.name,
-      quality: item.quality > 0 ? item.quality - qualityDecay : 0,
+      quality: item.quality - this._getDecayAmount(item),
       sellIn: item.sellIn - 1,
     };
+    return this._applyQualityLimitation(newItem);
   };
 
   private _decayLegendaryItem = (item: Item): Item => {
@@ -82,11 +84,25 @@ export class GildedRose {
   };
 
   private _applyQualityLimitation = (item: Item): Item => {
+    let newQuality = item.quality;
+    if (item.quality > this.QUALITY_LIM) {
+      newQuality = this.QUALITY_LIM;
+    } else if (item.quality < 0) {
+      newQuality = 0;
+    }
     return {
       name: item.name,
-      quality:
-        item.quality > this.QUALITY_LIM ? this.QUALITY_LIM : item.quality,
+      quality: newQuality,
       sellIn: item.sellIn,
     };
   };
+
+  private _getDecayAmount = (item: Item): number => {
+    const decayAmount = item.sellIn > 0 ? 1 : 2;
+    if (this._isConjured(item.name)) {
+      return decayAmount * 2;
+    } else {
+      return decayAmount;
+    }
+  };
 }

TypeScript/test/jest/gilded-rose.spec.ts

@@ -8,6 +8,8 @@ const legendaryItem = (sellIn: number, quality: number) =>
   new Item("Sulfuras, Hand of Ragnaros", sellIn, quality);
 const backstagePassItem = (sellIn: number, quality: number) =>
   new Item("Backstage passes to a TAFKAL80ETC concert", sellIn, quality);
+const conjuredItem = (sellIn: number, quality: number) =>
+  new Item("Conjured test item", sellIn, quality);
 
 describe("Gilded Rose", () => {
   it("should degrade quality", () => {
@@ -102,4 +104,25 @@ describe("Gilded Rose", () => {
       expect(items[0].quality).toBe(50);
     });
   });
+
+  describe("conjured", () => {
+    it("should degrade quality", () => {
+      const gildedRose = new GildedRose([conjuredItem(1, 3)]);
+      const items = gildedRose.updateQuality();
+      expect(items[0].sellIn).toBe(0);
+      expect(items[0].quality).toBe(1);
+    });
+    it("should degrade quality twice as fast past sell in date", () => {
+      const gildedRose = new GildedRose([conjuredItem(0, 4)]);
+      const items = gildedRose.updateQuality();
+      expect(items[0].sellIn).toBe(-1);
+      expect(items[0].quality).toBe(0);
+    });
+    it("should not degrade quality past 0", () => {
+      const gildedRose = new GildedRose([conjuredItem(0, 1)]);
+      const items = gildedRose.updateQuality();
+      expect(items[0].sellIn).toBe(-1);
+      expect(items[0].quality).toBe(0);
+    });
+  });
 });