Chess

Package Outline

com.ben.chess
|
|- boards
   |- ChessBoard
      |- StandardChessBoard
|- games
   |- ChessGame
      |- StandardChessGame
|- pieces
   |- ChessPiece
      |- Rook
      |- Knight
      |- Bishop
      |- Queen
      |- King
      |- Pawn
   |- behaviors
      |- UnobstructedBehavior
         |- RookBehavior   --\
         |                    >-- QueenBehavior -> KingBehavior    
         |- BishopBehavior --/
|- Player

Object Tree

ChessGame
|- ChessBoard
   |- ChessPiece
   |- ChessPiece
   |- ...

Overview

Pieces

ChessPieces extend from com.ben.chess.pieces.ChessPiece and should mostly concern themselves with overriding the canMove function.

Behaviors

Besides the Knight and Pawn, the other pieces in Chess share a lot in common. For example, a Queen is a mix of a Bishop and Rook. A King is just a Queen that can only move in a radius of 1.

Behaviors are reusable bits of logic that make overriding canMove simpler. For example, you can use RookBehavior to allow a piece to move in straight lights. Another common behavior is UnobstructedBehavior, which stops a piece from passing through other pieces.

As a bonus, behavior tests can be "stacked" too, which means you can assert that a Queen behaves like a Rook and Bishop instead of copying bits and pieces of both test suites over.

Boards

ChessBoards extend from com.ben.chess.boards.ChessBoard and are two dimensional arrays of ChessBoardCell. They should override getBoard to define the playing field.

Games

Games extend from com.ben.chess.games.ChessGame, which implements a game loop and rules common to most chess variants. The move method should be overridden to modify game logic.

Tests

You can diff the GUI output with the reference images in tests

Start a chess game.

White should be on top
There should be a row of pawns on each side
There should be a rook on each corner
Next to the rooks should be a knight
Next to each knight should be a bishop
Between the bishops should be a Queen and a King

Move white's fourth leftmost pawn down one cell Move black's third leftmost pawn up one cell Move white's queen to check black's king

There should be a red stroke around black's king
Moving any piece other than the second leftmost pawn should be an invalid move
Moving the second leftmost pawn up one cell should end the check and clear the red stroke

Click surrender

Black should be given the option to accept a tie
If yes, the score should remain the same
If no, black should have one point, while white has zero

ben-ng / checkmate