Table of Contents Basics Trip service Gilded Rose goal Existing Task Rules

Steps:

• before try to add new behaviour, check if it can be easily done
• if not, consider refactoring existing codebase to
  • do your change easily afterwards
  • understand the actual behavior and solving any contradictions between existing and new business rules
• to refactor an existing codebase and not causing regressions, you need to test after each change
• the easiest way is to
  • begin putting it under an automatic test harness
  • then refactoring
• when you finish your refactoring, introduce your changes
• consider putting a git pre-commit hook that will run the tests (just in case)

Baby steps on these kata:

• is there any test ?
  • if so, run them
  • run coverage and mutation tests
  • run tests to cover missing part
• no tests at all, do characterization test
  • write assertion on output, assert it wil be false
  • run test
  • replace the expected output by test actual result
• break dependencies

More on this with Michael Feathers

GitHub

source to refactor here

Overview:

• our goods are constantly degrading in quality as they approach their sell by date.
• system in place that updates our inventory (SellIn , Quantity)
• add selling a new category of items

Basics:

• sellIn : remaining number of days we have to sell the item (number of days before expiration date is reached)
• Quality : how valuable the item is
• At the end of each day, sellIn and Quality decreases

Quality

• is never negative
• is never more than 50
• its range is is ] 0; 50 ]

Once the sell by date has passed

• Quality degrades twice as fast

Special cases

• Aged Brie
  • increases in Quality the older it gets
• Sulfuras
  • never has to be sold
  • its Quality is 80 and never decreases
• Backstage passes
  • like aged brie, increases in Quality as its SellIn decrease (concert approach)
  • 10 days or less : increases by 2
  • 5 days or less : increases by 3
  • after concert (SellIn = 0): drops to 0

Add conjured items.

• “Conjured” items degrade in Quality twice as fast as normal items

List:

• change UpdateQuality method
• you can make the UpdateQuality method and Items property static
• do NOT change the Item class (including or Items property )