refactored with strategy pattern + factory and added test cases

TypeScript/app/gilded-rose.ts

@@ -1,69 +1,11 @@
-export class Item {
-  name: string;
-  sellIn: number;
-  quality: number;
-
-  constructor(name, sellIn, quality) {
-    this.name = name;
-    this.sellIn = sellIn;
-    this.quality = quality;
-  }
-}
-
+import Item from "./models/Item";
+import { UpdateStrategyFactory } from "./updateStrategyFactory";
 export class GildedRose {
-  items: Array<Item>;
+  private constructor() {}
 
-  constructor(items = [] as Array<Item>) {
-    this.items = items;
-  }
-
-  updateQuality() {
-    for (let i = 0; i < this.items.length; i++) {
-      if (this.items[i].name != 'Aged Brie' && this.items[i].name != 'Backstage passes to a TAFKAL80ETC concert') {
-        if (this.items[i].quality > 0) {
-          if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-            this.items[i].quality = this.items[i].quality - 1
-          }
-        }
-      } else {
-        if (this.items[i].quality < 50) {
-          this.items[i].quality = this.items[i].quality + 1
-          if (this.items[i].name == 'Backstage passes to a TAFKAL80ETC concert') {
-            if (this.items[i].sellIn < 11) {
-              if (this.items[i].quality < 50) {
-                this.items[i].quality = this.items[i].quality + 1
-              }
-            }
-            if (this.items[i].sellIn < 6) {
-              if (this.items[i].quality < 50) {
-                this.items[i].quality = this.items[i].quality + 1
-              }
-            }
-          }
-        }
-      }
-      if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-        this.items[i].sellIn = this.items[i].sellIn - 1;
-      }
-      if (this.items[i].sellIn < 0) {
-        if (this.items[i].name != 'Aged Brie') {
-          if (this.items[i].name != 'Backstage passes to a TAFKAL80ETC concert') {
-            if (this.items[i].quality > 0) {
-              if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-                this.items[i].quality = this.items[i].quality - 1
-              }
-            }
-          } else {
-            this.items[i].quality = this.items[i].quality - this.items[i].quality
-          }
-        } else {
-          if (this.items[i].quality < 50) {
-            this.items[i].quality = this.items[i].quality + 1
-          }
-        }
-      }
-    }
-
-    return this.items;
+  static updateQuality(items = [] as Array<Item>) {    
+    let updatedItems = items.map(
+      item => UpdateStrategyFactory.getUpdateStrategy(item).updateItem(item));
+    return updatedItems;
   }
 }

TypeScript/app/models/Item.ts

@@ -0,0 +1,11 @@
+export default class Item {
+  name: string;
+  sellIn: number;
+  quality: number;
+
+  constructor(name, sellIn, quality) {
+    this.name = name;
+    this.sellIn = sellIn;
+    this.quality = quality;
+  }
+}

TypeScript/app/updateStrategies/AgedBrieStrategy.ts

@@ -0,0 +1,12 @@
+import Item from "./../models/Item";
+import IUpdateStrategy from "./IUpdateStrategy";
+
+export default class AgedBrieStrategy implements IUpdateStrategy {    
+    constructor(private qualityFactor : number) {}
+
+    updateItem(item: Item) : Item {
+        let quality = Math.min(50, item.quality + 1 * this.qualityFactor);
+        let sellIn = item.sellIn - 1;
+        return new Item(item.name, sellIn, quality);
+    }
+}

TypeScript/app/updateStrategies/BackstagePassStrategy.ts

@@ -0,0 +1,20 @@
+import Item from "./../models/Item";
+import IUpdateStrategy from "./IUpdateStrategy";
+
+export default class BackstagePassStrategy implements IUpdateStrategy {
+    updateItem(item: Item) : Item {
+        let increaseFactor = this.getIncreaseFactor(item.sellIn);
+        let newQuality = 
+            increaseFactor 
+                ? Math.min(50, item.quality + increaseFactor) 
+                : 0;
+        let newSellIn = item.sellIn - 1;
+        return new Item(item.name, newSellIn, newQuality);
+    }
+
+    private getIncreaseFactor(sellIn: number){
+        if (sellIn > 10) return 1;
+        if (sellIn <= 10 && sellIn > 5) return 2;
+        if (sellIn <= 5 && sellIn > 0) return 3;
+    }
+}

TypeScript/app/updateStrategies/DefaultStrategy.ts

@@ -0,0 +1,13 @@
+import Item from "./../models/Item";
+import IUpdateStrategy from "./IUpdateStrategy";
+
+
+export default class DefaultStrategy implements IUpdateStrategy {    
+    constructor(private qualityFactor : number) {}
+
+    updateItem(item: Item) : Item {
+        let newQuality = Math.max(0, item.quality - this.qualityFactor);
+        let newSellIn = item.sellIn - 1;
+        return new Item(item.name, newSellIn, newQuality);
+    }
+}

TypeScript/app/updateStrategies/IUpdateStrategy.ts

@@ -0,0 +1,6 @@
+import Item from "./../models/Item";
+
+
+export default interface IUpdateStrategy {
+    updateItem(item: Item) : Item;
+}

TypeScript/app/updateStrategies/NoUpdateStrategy.ts

@@ -0,0 +1,8 @@
+import Item from "@/models/Item";
+import IUpdateStrategy from "./IUpdateStrategy";
+
+export default class NoUpdateStrategy implements IUpdateStrategy {
+    updateItem(item: Item) : Item {        
+        return new Item(item.name, item.sellIn, item.quality);
+    }
+}

TypeScript/app/updateStrategies/conjuredStrategy.ts

@@ -0,0 +1,12 @@
+import Item from "./../models/Item";
+import IUpdateStrategy from "./IUpdateStrategy";
+
+export default class ConjuredStrategy implements IUpdateStrategy {
+    constructor(private qualityFactor : number) {}
+
+    updateItem(item: Item) : Item {
+        let quality = Math.max(0, item.quality - 2 * this.qualityFactor);
+        let sellIn = item.sellIn - 1;
+        return new Item(item.name, sellIn, quality);
+    }
+}

TypeScript/app/updateStrategyFactory.ts

@@ -0,0 +1,27 @@
+import Item from "./models/Item";
+import AgedBrieStrategy from "./updateStrategies/AgedBrieStrategy";
+import BackstagePassStrategy from "./updateStrategies/BackstagePassStrategy";
+import ConjuredStrategy from "./updateStrategies/conjuredStrategy";
+import DefaultStrategy from "./updateStrategies/DefaultStrategy";
+import IUpdateStrategy from "./updateStrategies/IUpdateStrategy";
+import NoUpdateStrategy from "./updateStrategies/NoUpdateStrategy";
+
+export class UpdateStrategyFactory {
+    static getUpdateStrategy(item: Item): IUpdateStrategy {
+
+        let qualityFactor = item.sellIn <= 0 ? 2 : 1;
+
+        switch (item.name) {
+            case 'Aged Brie':
+                return new AgedBrieStrategy(qualityFactor);
+            case 'Sulfuras, Hand of Ragnaros':
+                return new NoUpdateStrategy();
+            case 'Backstage passes to a TAFKAL80ETC concert':
+                return new BackstagePassStrategy();
+            case 'conjured':
+                return new ConjuredStrategy(qualityFactor);
+            default:
+                return new DefaultStrategy(qualityFactor);
+        }
+    }
+}

TypeScript/test/golden-master-text-test.ts

@@ -1,4 +1,5 @@
-import { Item, GildedRose } from '../app/gilded-rose';
+import { GildedRose } from '../app/gilded-rose';
+import Item from "../app/models/Item";
 
 const items = [
   new Item("+5 Dexterity Vest", 10, 20), //
@@ -12,9 +13,6 @@ const items = [
   // this conjured item does not work properly yet
   new Item("Conjured Mana Cake", 3, 6)];
 
-
-const gildedRose = new GildedRose(items);
-
 let days: number = 2;
 if (process.argv.length > 2) {
     days = +process.argv[2];
@@ -28,5 +26,5 @@ for (let i = 0; i < days; i++) {
 
   });
   console.log();
-  gildedRose.updateQuality();
+  GildedRose.updateQuality(items);
 }

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

@@ -1,9 +1,46 @@
-import { Item, GildedRose } from '@/gilded-rose';
+import { GildedRose } from '@/gilded-rose';
+import Item from "@/models/Item";
 
 describe('Gilded Rose', () => {
-  it('should foo', () => {
-    const gildedRose = new GildedRose([new Item('foo', 0, 0)]);
-    const items = gildedRose.updateQuality();
-    expect(items[0].name).toBe('fixme');
-  });
+    it.each`
+    name           | quality | expectedQuality | sellIn | expectedSellIn | description
+    ${'abc def'}   | ${0}    | ${0}            | ${8}   | ${7}           | ${"quality should not be negative"}
+    ${'abc def'}   | ${0}    | ${0}            | ${0}   | ${-1}          | ${"sellIn should decrease"}
+    ${'abc def'}   | ${8}    | ${6}            | ${0}   | ${-1}          | ${"quality should decrease twice after sellIn is negative"}
+    ${'Aged Brie'} | ${0}    | ${1}            | ${8}   | ${7}           | ${"should increase quality by 1"}
+    ${'Aged Brie'} | ${0}    | ${2}            | ${0}   | ${-1}          | ${"should increase quality by 1"}
+    ${'Aged Brie'} | ${50}   | ${50}           | ${8}   | ${7}           | ${"quality should not be higher than 50"}
+    ${'conjured'}  | ${0}    | ${0}            | ${8}   | ${7}           | ${"quality should not be negative"}
+    ${'conjured'}  | ${0}    | ${0}            | ${0}   | ${-1}          | ${"quality should not be negative"}
+    ${'conjured'}  | ${4}    | ${2}            | ${8}   | ${7}           | ${"quality should decrease by 2"}
+    ${'conjured'}  | ${4}    | ${0}            | ${0}   | ${-1}          | ${"quality should decrease by 4 when sellIn is <= 0"}
+    ${'Sulfuras, Hand of Ragnaros'} | ${10} | ${10} | ${10} | ${10}      | ${"should not change "}
+    ${'Backstage passes to a TAFKAL80ETC concert'} | ${10}| ${11}| ${11} | ${10} | ${"quality increases by 1 for sellIn > 10"}
+    ${'Backstage passes to a TAFKAL80ETC concert'} | ${10}| ${11}| ${30} | ${29} | ${"quality increases by 1 for sellIn > 10"}
+    ${'Backstage passes to a TAFKAL80ETC concert'} | ${10}| ${12}| ${10} | ${9} | ${"quality increases by 2 for sellIn <= 10 && > 5"}
+    ${'Backstage passes to a TAFKAL80ETC concert'} | ${10}| ${12}| ${6}  | ${5} | ${"quality increases by 2 for sellIn <= 10 && > 5"}
+    ${'Backstage passes to a TAFKAL80ETC concert'} | ${10}| ${13}| ${5}  | ${4} | ${"quality increases by 3 for sellIn <= 5 && >= 0"}
+    ${'Backstage passes to a TAFKAL80ETC concert'} | ${10}| ${13}| ${1}  | ${0} | ${"quality increases by 3 for sellIn <= 5 && > 0"}
+    ${'Backstage passes to a TAFKAL80ETC concert'} | ${10}| ${0} | ${0}  | ${-1} | ${"quality is 0 if sellIn is exceeded"}
+    ${'Backstage passes to a TAFKAL80ETC concert'} | ${10}| ${0} | ${-1}  | ${-2} | ${"quality is 0 if sellIn is exceeded"}
+`("'$description' for '$name' with quality '$quality' and sellIn '$sellIn'", ({name, quality, expectedQuality, sellIn, expectedSellIn, description}) => {
+      const item1 = new Item(name, sellIn, quality);
+      const items = GildedRose.updateQuality([item1]);
+      expect(items[0].name).toBe(name);
+      expect(items[0].quality).toBe(expectedQuality);
+      expect(items[0].sellIn).toBe(expectedSellIn);
+    });
+    
+    it("should be correct for 2 items", () => {
+      const item1 = new Item('abc def', 8, 5);
+      const item2 = new Item('Aged Brie', 10, 2);
+      const items = GildedRose.updateQuality([item1, item2]);
+      expect(items[0].name).toBe(item1.name);
+      expect(items[0].quality).toBe(4);
+      expect(items[0].sellIn).toBe(7);
+      expect(items[1].name).toBe(item2.name);
+      expect(items[1].quality).toBe(3);
+      expect(items[1].sellIn).toBe(9);
+    });
 });
+

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

@@ -1,10 +1,11 @@
 import { expect } from 'chai';
-import { Item, GildedRose } from '@/gilded-rose';
+import { GildedRose } from '@/gilded-rose';
+import Item from "@/models/Item";
 
 describe('Gilded Rose', () => {
   it('should foo', () => {
-    const gildedRose = new GildedRose([new Item('foo', 0, 0)]);
-    const items = gildedRose.updateQuality();
-    expect(items[0].name).to.equal('fixme');
+    // const gildedRose = new GildedRose([new Item('foo', 0, 0)]);
+    // const items = gildedRose.updateQuality();
+    expect("items[0].name").to.equal('fixme');
   });
 });