public void Get_Piece_Added_To_Position()
{
var pawn = Substitute.For <IChessPiece>();
_chessBoard.Add(pawn, 0, 0, pawn.Color);
IChessPiece piece;
Assert.That(_chessBoard.TryGetPieceOn(0, 0, out piece), Is.True);
Assert.That(piece, Is.SameAs(pawn));
}
private bool CheckEnPassant(IChessBoard board, Move move)
{
// en passant can only apply on ranks three from the enemies home
if (move.Piece.Color == PieceColor.White && move.EndingY != board.Height - 3)
{
return(false);
}
if (move.Piece.Color == PieceColor.Black && move.EndingY != 2)
{
return(false);
}
// get the piece behind the target move point
int forwardDirection = move.Piece.Color == PieceColor.White ? 1 : -1;
IChessPiece targetPiece = null;
bool targetSquareOccupied = board.TryGetPieceOn(move.EndingX, move.EndingY - forwardDirection, out targetPiece);
if (!targetSquareOccupied)
{
return(false);
}
if (!(targetPiece is IPawn))
{
return(false);
}
// En Passant can only be applied on the next turn after the piece moves.
IPawn pawn = targetPiece as IPawn;
return(board.CurrentTurn == pawn.FirstMovedOn + 1);
}
public bool IsMoveValid(IChessBoard board, Move move)
{
IChessPiece capture;
bool occupied = board.TryGetPieceOn(move.EndingX, move.EndingY, out capture);
return(!occupied || move.Piece.Color != capture.Color);
}
private void UnoccupyBoard(IChessBoard board)
{
IChessPiece outVar = null;
board.TryGetPieceOn(Arg.Any <int>(), Arg.Any <int>(), out outVar).Returns(args => {
args[2] = null;
return(false);
});
}
private void OccupyRow(IChessBoard board, PieceColor color, int y)
{
IChessPiece outVar = null;
var occupier = Substitute.For <IPawn>();
occupier.Color.Returns(color);
occupier.FirstMovedOn.Returns(1);
board.TryGetPieceOn(Arg.Any <int>(), y, out outVar).Returns(args => {
args[2] = occupier;
return(true);
});
board.TryGetPieceOn(Arg.Any <int>(), Arg.Is <int>(y1 => y1 != y), out outVar).Returns(args => {
args[2] = null;
return(false);
});
}
/// <summary>
/// Checks board state to see if the move is valid.
/// </summary>
/// <param name="board">Board state to validate against</param>
/// <param name="move">Move to be performed</param>
/// <returns>True if the move is legal.</returns>
public bool IsMoveValid(IChessBoard board, Move move)
{
int forwardDirection = move.Piece.Color == PieceColor.White ? 1 : -1;
// pawns can only move forwards
if (((move.EndingY - move.StartingY) * forwardDirection) <= 0)
{
return(false);
}
// pawns can only move forwards two squares at most
if (((move.EndingY - move.StartingY) * forwardDirection) > 2)
{
return(false);
}
// pawns cannot move horiztally more than one square
if (move.StartingX - move.EndingX > 1 || move.EndingX - move.StartingX > 1)
{
return(false);
}
// pawns can only move forward two squares from their home rank
if (move.EndingY - move.StartingY == 2) // for white
{
if (move.Piece.Color == PieceColor.Black)
{
return(false);
}
if (move.StartingY != 1)
{
return(false);
}
if (move.StartingX != move.EndingX)
{
return(false); // cannot move horizontally during double step
}
}
if (move.StartingY - move.EndingY == 2) // for black
{
if (move.Piece.Color == PieceColor.White)
{
return(false);
}
if (move.StartingY != 6)
{
return(false);
}
if (move.StartingX != move.EndingX)
{
return(false); // cannot move horizontally during double step
}
}
IChessPiece targetPiece = null;
bool targetSquareOccupied = board.TryGetPieceOn(move.EndingX, move.EndingY, out targetPiece);
// pawns cannot move directly forward into an occupied square
if (move.StartingX - move.EndingX == 0)
{
return(!targetSquareOccupied);
}
// capture move check
if (move.StartingX - move.EndingX == 1 || move.EndingX - move.StartingX == 1)
{
return((targetSquareOccupied && targetPiece.Color != move.Piece.Color) || CheckEnPassant(board, move));
}
return(false);
}