My take(s) at the Gilded Rose kata.
Original: https://github.com/emilybache/GildedRose-Refactoring-Kata
Hi and welcome to team Gilded Rose. As you know, 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. 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 inquality
the older it gets.- The
quality
of an item is never more than50
. "Sulfuras"
, being a legendary item, never has to be sold or decreases inquality
."Backstage passes"
, like aged brie, increases inquality
as itssellIn
value approaches;quality
increases by2
when there are 10 days or less and by3
when there are 5 days or less, butquality
drops to0
after the concert.
Your task:
We have recently signed a supplier of conjured items. This requires an update to our system:
"Conjured"
items degrade inquality
twice as fast as normal items.
Rules:
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.
- Used Jest's
toMatchSnapshot()
for approval testing. - Added an enum to identify items types (
AgedBrie
,BackstagePass
,Common
, etc.). - Processed each item kind update separately, with functions.
- Items are treated as immutable (although the original
Item
class allows for modifications).
- Used
Insta
crate for approval testing. - Added an enum to identify item types. Used this enum as a factory to create instances of types that implement an
ItemUpdater
trait. - We have specific types that implement
ItemUpdater
, one for each item kind. This way we decouple theGildedRose
type from knowing which items types we have available and how to process them.