Simple TicTacToe kata.
The rules of the tic tac toe game are the following:
* a game is over when all fields are taken * a game is over when all fields in a column are taken by a player * a game is over when all fields in a row are taken by a player * a game is over when all fields in a diagonal are taken by a player * a player can take a field if not already taken * players take turns taking fields until the game is over * there are two player in the game (X and O)
See Wikipedia - TicTacToe for all the info.
Try following Object Calisthenics by Jeff Bay
In the following, I will review each of these 9 rules listed below:
* only one level of indentation per method * don't use the else keyword * wrap all primitives and strings * first class collections * one dot per line * don't abbreviate * keep all entities small * no classes with more than two instance variables * no getters/setters/properties