Arcade Techinical interview

gilded_rose.rb

class GildedRose

  def initialize(items)
    @items = items
  end

  def update_quality()
    @items.each do |item|
      case item.name
      when "Aged Brie"
        item.sell_in -= 1
        if item.quality < 50
          item.quality += 1
          item.quality += 1 if item.sell_in < 0
        end
      when "Backstage passes to a TAFKAL80ETC concert"
        item.sell_in -= 1
        if item.sell_in < 0
          item.quality = 0
        elsif item.sell_in < 5
          item.quality += 3
        elsif item.sell_in < 10
          item.quality += 2
        else
          item.quality += 1
        end
        item.quality = 50 if item.quality > 50
      when "Sulfuras, Hand of Ragnaros"
        # do nothing legendary is always valuable
      when "Conjured Mana Cake"
        item.sell_in -= 1
        item.quality -= 2
        item.quality -= 2 if item.sell_in < 0
      else
        item.sell_in -= 1
        item.quality -= 1
        item.quality -= 1 if item.sell_in < 0
      end
      item.quality = 0 if item.quality < 0
    end
  end
end

class Item
  attr_accessor :name, :sell_in, :quality

  def initialize(name, sell_in, quality)
    @name = name
    @sell_in = sell_in
    @quality = quality
  end

  def to_s()
    "#{@name}, #{@sell_in}, #{@quality}"
  end
end

gilded_rose_spec.rb

require File.join(File.dirname(__FILE__), 'gilded_rose')

describe GildedRose do

  describe "#update_quality" do
    subject {gildedrose.update_quality}

    let(:gildedrose) { GildedRose.new(items) }

    context 'when there are multiple items ' do
      let(:items) { [Item.new(name="Aged Brie", sell_in=2, quality=0), Item.new(name="Conjured Mana Cake", sell_in=3, quality=10)] }

      it 'updates all of them' do
        expect(subject.first.sell_in).to eq(1)
        expect(subject.last.sell_in).to eq(2)
      end
    end

    context 'when quality would go below 0' do
      let(:items) { [Item.new(name="+5 Dexterity Vest", sell_in=2, quality=0)] }

      it 'is set to 0' do
        expect(subject.first.quality).to eq(0)
      end
    end

    context 'brie' do
      let(:items) { [Item.new(name="Aged Brie", sell_in=2, quality=0)] }

      it 'decreases the sell in' do
        expect(subject.first.sell_in).to eq(1)
      end

      context 'when the sell_in is 0' do
        let(:items) { [Item.new(name="Aged Brie", sell_in=0, quality=0)] }

        it 'increase in quality at twice as fast' do
          expect(subject.first.quality).to eq(2)
        end
      end

      context 'when quality is less than 50' do
        it 'increases in quality' do
          expect(subject.first.quality).to eq(1)
        end
      end

      context 'when quality is 50' do
        let(:items) { [Item.new(name="Aged Brie", sell_in=2, quality=50)] }

        it 'does not increase in quality' do
          expect(subject.first.quality).to eq(50)
        end
      end
    end

    context 'backstage passes' do
      let(:items) { [Item.new(name="Backstage passes to a TAFKAL80ETC concert", sell_in=15, quality=20)] }

      it 'increases in quality' do
        expect(subject.first.quality).to eq(21)
      end
      it 'decreases the sell in' do
        expect(subject.first.sell_in).to eq(14)
      end

      context 'when quality is 50 or less' do
        context 'when sell in is 10 or less and greater than 5' do
          let(:items) { [Item.new(name="Backstage passes to a TAFKAL80ETC concert", sell_in=6, quality=20)] }

          it 'increases in quality at double rate'do
            expect(subject.first.quality).to eq(22)
          end
        end

        context 'when sell in is 5 or less' do
          let(:items) { [Item.new(name="Backstage passes to a TAFKAL80ETC concert", sell_in=3, quality=20)] }

          it 'increases in quality at triple rate' do
            expect(subject.first.quality).to eq(23)
          end
        end
      end

      context 'when quality is 50' do
        let(:items) { [Item.new(name="Backstage passes to a TAFKAL80ETC concert", sell_in=15, quality=50)] }

        it 'does not increase in quality' do
          expect(subject.first.quality).to eq(50)
        end
      end

      context 'when sell in is negative' do
        let(:items) { [Item.new(name="Backstage passes to a TAFKAL80ETC concert", sell_in=0, quality=20)] }

        it 'quailty is 0' do
          expect(subject.first.quality).to eq(0)
        end
      end
    end

    context 'legendary item' do
      let(:items) { [Item.new(name="Sulfuras, Hand of Ragnaros", sell_in=0, quality=80)] }

      it 'does not decrease in quality' do
        expect( subject.first.quality).to eq(80)
      end
      it 'does not decrease sell_in' do
        expect(subject.first.sell_in).to eq(0)
      end
    end

    context 'Conjured Mana Cake' do
      let(:items) { [Item.new(name="Conjured Mana Cake", sell_in=3, quality=10)] }

      it 'descreaseing in quality twice as fast' do
        expect(subject.first.quality).to eq(8)
      end
      it 'decreases the sell in' do
        expect(subject.first.sell_in).to eq(2)
      end

      context 'when the sell in is past' do
        let(:items) { [Item.new(name="Conjured Mana Cake", sell_in=0, quality=10)] }


        it 'decreases in quality four times as fast' do
          expect(subject.first.quality).to eq(6)
        end
      end
    end

    context 'basic item' do
      let(:items) { [Item.new(name="+5 Dexterity Vest", sell_in=10, quality=20)] }

      it 'descreaseing in quality' do
        expect(subject.first.quality).to eq(19)
      end
      it 'decreases the sell in' do
        expect(subject.first.sell_in).to eq(9)
      end

      context 'when the sell in is past' do
        let(:items) { [Item.new(name="+5 Dexterity Vest", sell_in=0, quality=20)] }

        it 'decreases in quality twice as fast' do
          expect(subject.first.quality).to eq(18)
        end
      end
    end

    it "does not change the name" do
      items = [Item.new("foo", 0, 0)]
      GildedRose.new(items).update_quality()
      expect(items[0].name).to eq "foo"
    end
  end

end