chris-softdev / gilded-rose-javascript

Gilded Rose Kata in JavaScript

Gilded Rose

Hi and welcome to team Gilded Rose.

We are a small inn with a prime location in a prominent city ran 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.

Specifications

First an introduction to our system:

• All items have a sellIn field which denotes the number of days we have to sell the item.
• All items have a quality field which denotes the item's value.
• 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 sellIn days is less then zero, 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, Hand of Ragnaros," being a legendary item, never has to be sold nor does it decrease in quality.
• "Backstage passes to a TAFKAL80ETC concert", increase in quality as it's sellIn value decreases:
  • quality increases by 2 when there are 10 days or less left before the concert.
  • quality increases by 3 when there are 5 days or less left before the concert.
  • 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 as it belong to the goblin in the corner who will insta-rage and one-shot you as he doesn't believe in shared code ownership.

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

Instructions

You are tasked with performing the following:

1. Writing Tests

Before refactoring the existing codebase, it's a good idea to write sufficient test-cases to codify the behavior of the current updateQuality implementation. You can use the specifications above as a guide for what tests you need to write. There is an example test in gilded-rose.spec.js to use as a guide.

The tests are written using vitest as the testing framework and are run using $ npm run test in your terminal.

2. Refactoring

Once you have a strong test suite to prevent you from breaking existing behavior, try to refactor the ugly updateQuality function, running the test suite periodically. Notice that the thing that makes updateQuality difficult to read is the number of nested conditionals. How can we utilize OOP to reduce the number of conditionals?

3. Completing the New Feature

Once your refactoring is complete, write a test to verify the new feature (making "Conjured" items degrade in quality twice as fast) and then implement the feature, ensuring it passes the new test.

That's it. Good luck, traveler!

Source: https://github.com/professor/GildedRose