GildedRose-Refactoring-Kata JS Results

gilded_rose.test.js

const { Shop, Item, SpecialItemName } = require('../src/gilded_rose');

const { ITEM_AGED_BRIE, ITEM_SULFURAS, ITEM_BACKSTAGE_PASS } = SpecialItemName;

describe('Gilded Rose', function() {
  it('the item foo should degrade both its quality and sellIn day', function() {
    const gildedRose = new Shop([new Item('foo', 10, 10)]);
    const items = gildedRose.updateQuality();
    const testItem = items[0];
    expect(testItem.name).toBe('foo');
    expect(testItem.sellIn).toBe(9);
    expect(testItem.quality).toBe(9);
  });

  it('all items should degrade both its quality and sellIn day', function() {
    const itemsToPassIn = [new Item('foo', 10, 10), new Item('bar', 10, 10)];
    const gildedRose = new Shop(itemsToPassIn);
    const items = gildedRose.updateQuality();
    const testItem1 = items[0];
    expect(testItem1.name).toBe('foo');
    expect(testItem1.sellIn).toBe(9);
    expect(testItem1.quality).toBe(9);
    const testItem2 = items[1];
    expect(testItem2.name).toBe('bar');
    expect(testItem2.sellIn).toBe(9);
    expect(testItem2.quality).toBe(9);
  });

  // 商品的品質的上限為50。
  it('should 商品的品質的上限為 50', function() {
    expect(() => {
      const itemsToPassIn = [new Item('foo', 10, 60)];
      const gildedRose = new Shop(itemsToPassIn);
      return gildedRose;
    }).toThrow('Quality Must < 50');
  });

  it('should 商品的品質的上限為 50 (2)', function() {
    const itemsToPassIn = [new Item(ITEM_AGED_BRIE, 10, 50)];
    const gildedRose = new Shop(itemsToPassIn);
    const items = gildedRose.updateQuality();
    const testItem1 = items[0];
    expect(testItem1.sellIn).toBe(9);
    expect(testItem1.quality).toBe(50);
  });

  // 商品的品質不能為負數。
  it('商品的品質不能為負數', function() {
    const itemsToPassIn = [new Item('foo', 10, 0)];
    const gildedRose = new Shop(itemsToPassIn);
    const items = gildedRose.updateQuality();
    const testItem1 = items[0];
    expect(testItem1.name).toBe('foo');
    expect(testItem1.sellIn).toBe(9);
    expect(testItem1.quality).toBe(0);
    gildedRose.updateQuality();
    expect(testItem1.name).toBe('foo');
    expect(testItem1.sellIn).toBe(8);
    expect(testItem1.quality).toBe(0);
  });

  // 一但商品過了銷售剩餘天數之後還沒未賣出，那麼其每日品質下降的速度就會加倍。
  it('一但商品過了銷售剩餘天數之後還沒未賣出，那麼其每日品質下降的速度就會加倍', function() {
    const itemsToPassIn = [new Item('foo', 0, 10)];
    const gildedRose = new Shop(itemsToPassIn);
    const items = gildedRose.updateQuality();

    const testItem1 = items[0];
    expect(testItem1.name).toBe('foo');
    expect(testItem1.sellIn).toBe(-1);
    expect(testItem1.quality).toBe(8);
  });

  // 陳年乾酪(Aged Brie)的品質值隨著時間的推移，不減反增。
  it('陳年乾酪(Aged Brie)的品質值隨著時間的推移，不減反增', function() {
    const itemsToPassIn = [new Item(ITEM_AGED_BRIE, 10, 10)];
    const gildedRose = new Shop(itemsToPassIn);
    const items = gildedRose.updateQuality();

    const testItem1 = items[0];
    expect(testItem1.name).toBe(ITEM_AGED_BRIE);
    expect(testItem1.sellIn).toBe(9);
    expect(testItem1.quality).toBe(11);
  });

  // 魔法錘(Sulfuras)是一個傳奇商品，其銷售剩餘天數和品質都不會變化。
  it('魔法錘(Sulfuras)是一個傳奇商品，其銷售剩餘天數和品質都不會變化。', function() {
    const itemsToPassIn = [new Item(ITEM_SULFURAS, 10, 10)];
    const gildedRose = new Shop(itemsToPassIn);
    const items = gildedRose.updateQuality();

    const testItem1 = items[0];
    expect(testItem1.name).toBe(ITEM_SULFURAS);
    expect(testItem1.sellIn).toBe(10);
    expect(testItem1.quality).toBe(10);
  });

  describe('劇院後台通行證(Backstage passes)', function() {
    it('就像陳年乾酪一樣，其品質會隨著銷售剩餘天數的減少而提高', function() {
      const itemsToPassIn = [new Item(ITEM_BACKSTAGE_PASS, 20, 10)];
      const gildedRose = new Shop(itemsToPassIn);
      const items = gildedRose.updateQuality();

      const testItem1 = items[0];
      expect(testItem1.name).toBe(ITEM_BACKSTAGE_PASS);
      expect(testItem1.sellIn).toBe(19);
      expect(testItem1.quality).toBe(11);
    });
    it('當離演出開始不到10天時，品質每日提高2', function() {
      const itemsToPassIn = [new Item(ITEM_BACKSTAGE_PASS, 10, 10)];
      const gildedRose = new Shop(itemsToPassIn);
      const items = gildedRose.updateQuality();

      const testItem1 = items[0];
      expect(testItem1.name).toBe(ITEM_BACKSTAGE_PASS);
      expect(testItem1.sellIn).toBe(9);
      expect(testItem1.quality).toBe(12);
    });
    it('當不到5天時，品質值每日提高3', function() {
      const itemsToPassIn = [new Item(ITEM_BACKSTAGE_PASS, 5, 10)];
      const gildedRose = new Shop(itemsToPassIn);
      const items = gildedRose.updateQuality();

      const testItem1 = items[0];
      expect(testItem1.name).toBe(ITEM_BACKSTAGE_PASS);
      expect(testItem1.sellIn).toBe(4);
      expect(testItem1.quality).toBe(13);
    });
    it('當演出結束後，品質歸0', function() {
      const itemsToPassIn = [new Item(ITEM_BACKSTAGE_PASS, 0, 10)];
      const gildedRose = new Shop(itemsToPassIn);
      const items = gildedRose.updateQuality();

      const testItem1 = items[0];
      expect(testItem1.name).toBe(ITEM_BACKSTAGE_PASS);
      expect(testItem1.sellIn).toBe(-1);
      expect(testItem1.quality).toBe(0);
    });
  });
});

glided_rose.js

const ITEM_AGED_BRIE = 'Aged Brie';
const ITEM_BACKSTAGE_PASS = 'Backstage passes to a TAFKAL80ETC concert';
const ITEM_SULFURAS = 'Sulfuras, Hand of Ragnaros';

class Item {
  constructor(name, sellIn, quality) {
    this.name = name;
    this.sellIn = sellIn;
    this.quality = quality;

    if (quality > 50) {
      throw new Error('Quality Must < 50');
    }
  }

  isUnderMaxQuality() {
    return this.quality < 50;
  }

  passOneDay() {
    const item = this;
    if (NotAffectedItemPolicy.canApplyTo(item)) {
      NotAffectedItemPolicy.passOneDay(item);
      return;
    }
    if (QualityIncreaseByTimeItemPolicy.canApplyTo(item)) {
      QualityIncreaseByTimeItemPolicy.passOneDay(item);
    }

    if (TicketItemPolicy.canApplyTo(item)) {
      TicketItemPolicy.passOneDay(item);
      return;
    }
    if (NormalItemPolicy.canApplyTo(item)) {
      NormalItemPolicy.passOneDay(item);
      return;
    }
  }
}

class NotAffectedItemPolicy {
  static canApplyTo(item) {
    return item.name === ITEM_SULFURAS;
  }
  static passOneDay(item) {
    return item;
  }
}

class NormalItemPolicy {
  static canApplyTo(item) {
    return ![ITEM_AGED_BRIE, ITEM_BACKSTAGE_PASS, ITEM_SULFURAS].includes(
      item.name
    );
  }
  static passOneDay(item) {
    if (!NormalItemPolicy.canApplyTo(item)) {
      throw new Error('Not Match');
    }
    item.sellIn = item.sellIn - 1;
    if (item.sellIn < 0) {
      item.quality = item.quality - 2;
      return;
    }
    if (item.quality > 0) {
      item.quality = item.quality - 1;
    }
  }
}

class QualityIncreaseByTimeItemPolicy {
  static canApplyTo(item) {
    return item.name === ITEM_AGED_BRIE;
  }

  static passOneDay(item) {
    if (!QualityIncreaseByTimeItemPolicy.canApplyTo(item)) {
      throw new Error('Wrong Name');
    }
    item.sellIn = item.sellIn - 1;
    if (item.isUnderMaxQuality()) {
      item.quality = item.quality + 1;
    }
    return;
  }
}

class TicketItemPolicy {
  static canApplyTo(item) {
    return item.name === ITEM_BACKSTAGE_PASS;
  }
  static passOneDay(item) {
    item.sellIn = item.sellIn - 1;
    if (item.sellIn < 0) {
      item.quality = 0;
      return;
    }
    if (!item.isUnderMaxQuality()) {
      return;
    }
    item.quality = item.quality + 1;
    if (item.sellIn < 11) {
      item.quality = item.quality + 1;
    }
    if (item.sellIn < 6) {
      item.quality = item.quality + 1;
    }
    return;
  }
}

class Shop {
  /**
   * @param {Item[]} items
   */
  constructor(items = []) {
    this.items = items;
  }

  updateQuality() {
    this.items.forEach(item => item.passOneDay());
    return this.items;
  }
}

module.exports = {
  Item,
  Shop,
  SpecialItemName: {
    ITEM_AGED_BRIE,
    ITEM_BACKSTAGE_PASS,
    ITEM_SULFURAS
  }
};

Hi Fong 感謝提供練習範例，讓我對重構後的模式又有了新的認知 XDD
想補充的一點是 TicketItemPolicy 裡的 passOneDay 好像跟原本的邏輯有點不一樣
原本邏輯是扣除銷售日期前是 sell In 是小於 11 及 小於 6 時才會去增加 quality
但因為重構後是先扣除銷售日期，所以 sell In 判斷應該減為 10 跟 5 才對

這可能是另一個議題是重構前單元測試要寫到多仔細，邊界測試可能要寫不夠滿嗎 QQ