In this repo I've cloned this Gilded Rose Refactoring Kata and refactored it. I've chosen to do this in Ruby and all the changes will therefore sit under directory labelled 'Ruby'.
- Ruby (version 2.4.0)
- RSpec (version 3.6.0)
*"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:*
- All items have a SellIn value (the number of days an item can be sold)
- All items have a Quality value (how valuable each item is)
- Once the sell by date has passed, qualtity decreases twice as fast
- The Quality of an item cannot be negative
- The Quality maximum value is 50
- "Aged Brie" increases in quality the older it gets
- "Sulfuras" is an exception: It has never has to be sold and it doesn't decrease in quality
- "Backstage passes" 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 left. But Quality drops to 0 after that date.
- "Conjured" items decrease in Quality twice as fast as normal items.
- Changes can be made to the UpdateQuality method and Items property statistic, however no changes can be made to the Item class or Items property.
- Navigate to your projects directory
- Run
git clone https://github.com/connie-reinholdsson/gilded-rose-refactoring-tech-test.git - Run
cd gilded-rose-refactoring-test - Run
cd ruby
This Kata was originally created by Terry Hughes (http://twitter.com/#!/TerryHughes). It is already on GitHub here. See also Bobby Johnson's description of the kata.
I translated the original C# into a few other languages, (with a little help from my friends!), and slightly changed the starting position. This means I've actually done a small amount of refactoring already compared with the original form of the kata, and made it easier to get going with writing tests by giving you one failing unit test to start with. I also added test fixtures for Text-Based approval testing with TextTest (see the TextTests)
As Bobby Johnson points out in his article "Why Most Solutions to Gilded Rose Miss The Bigger Picture", it'll actually give you better practice at handling a legacy code situation if you do this Kata in the original C#. However, I think this kata is also really useful for practicing writing good tests using different frameworks and approaches, and the small changes I've made help with that. I think it's also interesting to compare what the refactored code and tests look like in different programming languages.
I wrote this article "Writing Good Tests for the Gilded Rose Kata" about how you could use this kata in a coding dojo.
The simplest way is to just clone the code and start hacking away improving the design. You'll want to look at the "Gilded Rose Requirements" which explains what the code is for. I strongly advise you that you'll also need some tests if you want to make sure you don't break the code while you refactor.
You could write some unit tests yourself, using the requirements to identify suitable test cases. I've provided a failing unit test in a popular test framework as a starting point for most languages.
Alternatively, use the "Text-Based" tests provided in this repository. (Read more about that in the next section)
Whichever testing approach you choose, the idea of the exercise is to do some deliberate practice, and improve your skills at designing test cases and refactoring. The idea is not to re-write the code from scratch, but rather to practice designing tests, taking small steps, running the tests often, and incrementally improving the design.
This is a testing approach which is very useful when refactoring legacy code. Before you change the code, you run it, and gather the output of the code as a plain text file. You review the text, and if it correctly describes the behaviour as you understand it, you can "approve" it, and save it as a "Golden Master". Then after you change the code, you run it again, and compare the new output against the Golden Master. Any differences, and the test fails.
It's basically the same idea as "assertEquals(expected, actual)" in a unit test, except the text you are comparing is typically much longer, and the "expected" value is saved from actual output, rather than being defined in advance.
Typically a piece of legacy code may not produce suitable textual output from the start, so you may need to modify it before you can write your first text-based approval test. That could involve inserting log statements into the code, or just writing a "main" method that executes the code and prints out what the result is afterwards. It's this latter approach we are using here to test GildedRose.
The Text-Based tests in this repository are designed to be used with the tool "TextTest" (http://texttest.org). This tool helps you to organize and run text-based tests. There is more information in the README file in the "texttests" subdirectory.
I've also set this kata up on cyber-dojo for several languages, so you can get going really quickly:
- JUnit, Java
- C#
- C++
- Ruby
- RSpec, Ruby
- Python
- Cucumber, Java - for this one I've also written some step definitions for you
I analysed this repo according to the clean code standards on Better Code Hub just to get an independent opinion of how bad the code is. Perhaps unsurprisingly, the compliance score is low!