Gilded Rose Kata in TypeScript + Vitest

This repository contains a TypeScript implementation of the famous "Gilded Rose" kata. The kata focuses on refactoring an inventory management system for a shop, where products have different rules for quality updates.

Installation

Follow these steps to set up and run the kata in your local environment:

1. Install Dependencies

Make sure you have Node.js and Yarn installed on your machine. Then, run the following command to install project dependencies:

yarn install

2. Run Tests

After installing the dependencies, run the tests to ensure that the implementation meets the kata requirements. Use the following command:

yarn test

This command will execute the tests and provide information about coverage and any potential errors.

Gilded Rose Requirements Specification

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 a 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 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

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).

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.

Additional Resources

Here are some resources that may be useful for completing the Gilded Rose kata:

• Code Smells
• Clean Code Principles
• TypeScript Official Documentation

Feel free to explore these resources to enhance your understanding of clean code practices and refactoring techniques.