Background
A kata is an exercise in karate that is practiced over and over again to get down a technique. This is similar to the practice in software development, where a coding kata is meant to practice particular techniques in code in a small sample problem. The gilded rose is a long since popularized coding kata that involves refactoring. The idea behind it is to write a suite of tests, then refactor the code to be readable and maintainable.
The specification for the kata is given below:
This code is part of a larger fantasy battle game. Players in the game will fight
monsters using the equipment they are wearing. The type of equipment will affect
how much damage they do to the monsters. Monsters also vary according to what
armour and equipment they are wearing. This part of the code is concerned with
calculating how much damage the player is doing to a monster when they fight.
The kata is designed to teach you something about the Law of Demeter
(https://en.wikipedia.org/wiki/Law_of_Demeter). The 'Player' class perhaps doesn't
follow this law very well.
Try to write a test for the method 'calculateDamage' on the Player class, without
changing any of the production code. Use the description below to help you design
a test scenario. Note there are two example test cases to start from. Choose the
one you prefer. Give yourself a time box of 10 minutes, then reflect on why this
method is hard to test.
When you have reflected, you should refactor the 'calculateDamage' method to better
follow the Law of Demeter. Also add test cases to cover the functionality in the
Player class.
When you feel that you are done, depending on how much time you have, you may
continue to implement tests until you have good coverage or look through the TODO
in the code (Alt+6 in IntelliJ). Reflect on which of these TODO hints will now be
easier to address compared with before your refactoring work, then try to implement
those features.
Example Data for use in Test cases
----------------------------------
Example equipment:
| Where | What | Base Damage | Damage Modifier |
|-----------|-----------------|-------------|-----------------|
| right hand| flashy sword of danger | 10 | 1.0 |
| right hand| excalibur | 20 | 1.5 |
| left hand | round shield | 0 | 1.4 |
| feet | ten league boots | 0 | 0.1 |
| head | helmet of swiftness | 0 | 1.2 |
| chest | breastplate of steel | 0 | 1.4 |
At present the only kind of enemy supported is a SimpleEnemy. This kind of target
has one Buff with a soakModifier of 1.0 and damage modifier of 1.0. It wears an
Armor with a Damage Soak of 5.
Learnings
This kata teaches proper CQS (Command-Query Separation Principle) through showing Law Of Demeter violations and then getting the navigator/driver pair to resolve them. First write a suite of tests around the code, then solve the encapsulation issues using proper refactoring techniques.