The Gilded Rosebud Code Kata

This is the reverse of Jim Weirich's version of the Gilded Rose Kata. Jim's repository can be found here.

Jim created a working solution for the given suite of tests using a nasty set of conditionals. The goal was to refactor this while keeping the tests passing.

The goal of this version is to create working solutions from scratch while satisfying the tests. To make the most of the exercise, constraints can be introduced for added complexity and difficulty.

Suggestions for Constraints

• Conditionals vs. Polymorphism
  • begin by using exclusively conditionals/loops
  • convert to polymorphism (no conditionals/loops)
• Primitives vs. Objects
  • begin by using exclusively primitives (int/float/string/etc.)
  • collections should be arrays of primitives
  • convert to composed objects (all values as objects)
  • collections become single enumerable objects
• Mutability vs. Immutability *
  • begin with all domain concepts represented with state
  • convert to simple structures passed through sets of functions
• Method Size
  • begin with all behavior in a single method
  • extract methods no longer than 5 lines
  • extract methods no longer than 2 lines

* Immutability will require changes to the specs. This is part of the challenge.

Installation

Any version of Ruby at or above 1.9.3 should work just fine.

If you have RSpec installed globally, there is nothing you need to do. If you need to install it, the easiest way is to use bundler to install the dependencies. To do so, you need to install the bundler gem if you haven't already done so.

gem install bundler

Then, run bundler.

bundle

Running

To run the specs, use the rake tasks.

rake spec

or

rake

To stop the test runner at the first test failure:

rake fast

For convenience, all tests but the first are marked as pending. As you progress, unmark additional tests as pending to see them fail, then amend your implementation to satisfy the changing requirements.

Original Description of the Gilded Rose

Hi and welcome to team Gilded Rose. As you know, we are a small inn with a prime location in a prominent city run by a friendly innkeeper named Allison. We also buy and sell only the finest goods. Unfortunately, our goods are constantly degrading in quality as they approach their sell by date. We have a system in place that updates our inventory for us. It was developed by a no-nonsense type named Leeroy, who has moved on to new adventures. Your task is to add the new feature to our system so that we can begin selling a new category of items. First an introduction to our system:

• 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

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 it's 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

We have recently signed a supplier of conjured items. This requires an update to our system:

• "Conjured" items degrade in Quality twice as fast as normal items

Feel free to make any changes to the UpdateQuality method and add any new code as long as everything still works correctly. However, do not alter the Item class or Items property as those belong to the goblin in the corner who will insta-rage and one-shot you as he doesn't believe in shared code ownership (you can make the UpdateQuality method and Items property static if you like, we'll cover for you). Your work needs to be completed by Friday, February 18, 2011 08:00:00 AM PST.

Just for clarification, an item can never have its Quality increase above 50, however "Sulfuras" is a legendary item and as such its Quality is 80 and it never alters.