Slight refactor and small bugfix

Author: scl-softwire

chessington/engine/board.py

@@ -6,39 +6,31 @@
 from collections import namedtuple
 from enum import Enum, auto
 
+from chessington.engine.data import Player, Square
 from chessington.engine.pieces import Pawn, Knight, Bishop, Rook, Queen, King
 
 BOARD_SIZE = 8
 
-class Player(Enum):
+class Board:
     """
-    The two players in a game of chess.
+    A representation of the chess board, and the pieces on it.
     """
-    WHITE = auto()
-    BLACK = auto()
 
-
-class Square(namedtuple('Square', 'row col')):
-    """
-    An immutable pair (row, col) representing the coordinates of a square.
-    """
+    def __init__(self, player, board_state):
+        self.current_player = Player.WHITE
+        self.board = board_state
 
     @staticmethod
-    def at(row, col):
-        """
-        Creates a square at the given row and column.
-        """
-        return Square(row=row, col=col)
+    def empty():
+        return Board(Player.WHITE, Board._create_empty_board())
 
+    @staticmethod
+    def at_starting_position():
+        return Board(Player.WHITE, Board._create_starting_board())
 
-class Board:
-    """
-    A representation of the chess board, and the pieces on it.
-    """
-
-    def __init__(self):
-        self.current_player = Player.WHITE
-        self.board = Board._create_starting_board()
+    @staticmethod
+    def _create_empty_board():
+        return [[None] * BOARD_SIZE for _ in range(BOARD_SIZE)]
 
     @staticmethod
     def _create_starting_board():
@@ -87,4 +79,4 @@ def move_piece(self, from_square, to_square):
         if moving_piece is not None and moving_piece.player == self.current_player:
             self.set_piece(to_square, moving_piece)
             self.set_piece(from_square, None)
-            self.current_player = Player.WHITE if self.current_player == Player.BLACK else Player.WHITE
+            self.current_player = self.current_player.opponent()

chessington/engine/data.py

@@ -0,0 +1,30 @@
+"""
+Data classes for easy representation of concepts such as a square on the board or a player.
+"""
+
+from collections import namedtuple
+from enum import Enum, auto
+
+class Player(Enum):
+    """
+    The two players in a game of chess.
+    """
+    WHITE = auto()
+    BLACK = auto()
+
+    def opponent(self):
+        if self == Player.WHITE: return Player.BLACK
+        else: return Player.WHITE
+
+
+class Square(namedtuple('Square', 'row col')):
+    """
+    An immutable pair (row, col) representing the coordinates of a square.
+    """
+
+    @staticmethod
+    def at(row, col):
+        """
+        Creates a square at the given row and column.
+        """
+        return Square(row=row, col=col)

chessington/engine/pieces.py

@@ -4,6 +4,8 @@
 
 from abc import ABC, abstractmethod
 
+from chessington.engine.data import Player, Square
+
 class Piece(ABC):
     """
     An abstract base class from which all pieces inherit.

chessington/ui/__init__.py

@@ -6,7 +6,8 @@
 
 import PySimpleGUI as psg
 
-from chessington.engine.board import Player, Board, Square, BOARD_SIZE
+from chessington.engine.board import Board, BOARD_SIZE
+from chessington.engine.data import Player, Square
 from chessington.engine.pieces import Pawn, Knight, Bishop, Rook, Queen, King
 
 IMAGES_BASE_DIRECTORY = 'images'
@@ -68,7 +69,7 @@ def highlight_squares(window, from_square, to_squares):
 def play_game():
     psg.ChangeLookAndFeel('GreenTan')
 
-    board = Board()
+    board = Board.at_starting_position()
     board_layout = render_board(board)
     window = psg.Window('Chessington', default_button_element_size=(12, 1), auto_size_buttons=False).Layout(board_layout)
 

tests/test_board.py

@@ -1,9 +1,10 @@
-from chessington.engine.board import Board, Square, Player
+from chessington.engine.board import Board
+from chessington.engine.data import Player, Square
 
 def test_new_board_has_white_pieces_at_bottom():
 
     # Arrange
-    board = Board()
+    board = Board.at_starting_position()
 
     # Act
     piece = board.get_piece(Square.at(0, 0))
@@ -14,7 +15,7 @@ def test_new_board_has_white_pieces_at_bottom():
 def test_new_board_has_black_pieces_at_top():
 
     # Arrange
-    board = Board()
+    board = Board.at_starting_position()
 
     # Act
     piece = board.get_piece(Square.at(7, 0))
@@ -25,7 +26,7 @@ def test_new_board_has_black_pieces_at_top():
 def test_pieces_can_be_moved_on_the_board():
 
     # Arrange
-    board = Board()
+    board = Board.at_starting_position()
     from_square = Square.at(1, 0)
     piece = board.get_piece(from_square)