gilded-rose-kata

About the Gilded Rose kata

The Gilded Rose kata is a kata about a store where goods degrade in quality as they approach their sell date:

• All items have a SellIn value which denotes the number of days we have to sell the item
• All items have a Quality value which denotes how valuable the item is
• At the end of each day, our system lowers both values for every item

The item sell date and quality are daily updated by invocation of the associated update() method call. Pretty simple, right? Well, this is where it gets interesting:

• Once the sell by date has passed, Quality degrades twice as fast
• The Quality of an item is never negative
• "Aged Brie" actually increases in Quality the older it gets
• The Quality of an item is never more than 50
• "Sulfuras", being a legendary item, never has to be sold or decreases in Quality
• "Backstage passes", like aged brie, increases in Quality as its SellIn value approaches; Quality increases by 2 when there are 10 days or less and by 3 when there are 5 days or less but Quality drops to 0 after the concert

Eventual goal

The eventual goal of this kata is to add a new category of items, namely "Conjured" items that degrade in Quality twice as fast as normal items.

Creating a golden master

Before we can touch/modify/refactor an existing code base, we first have to make sure we keep the current behaviour unaltered. To this extent, we first have to create a snapshot or so-called golden master.

This is exactly what we will do in this exercise using approval testing.

References

• The Gilded Rose Refactoring Kata GitHub repository
• Refactoring the Gilded Rose manually versus using Sourcery
• Gilding the rose by Kevlin Henney
• Emily Bache
  • Introducing the Gilded Rose kata and writing test cases using Approval Tests
  • Refactoring item logic using ‘lift up conditional'
  • Replace Conditional with Polymorphism