Implement rook moves

chess/board.go

@@ -217,7 +217,85 @@ func (b *Board) movePawn(position string) error {
 }
 
 func (b *Board) moveRook(position string) error {
+	var (
+		x     int
+		y     int
+		xPrev int
+		yPrev int
+		piece *Piece
+		err   error
+	)
+
+	if x, y, err = getXY(position); err != nil {
+		return err
+	}
+
+	xPrev = x
+	yPrev = y
+	for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
+		xPrev++
+		piece = b.getPiece(xPrev, yPrev)
+		if piece != nil {
+			if piece.Name == Rook && piece.Color == b.turn {
+				b.tiles[xPrev][yPrev] = nil
+				b.tiles[x][y] = piece
 				return nil
+			} else {
+				// direction blocked by other piece
+				break
+			}
+		}
+	}
+
+	xPrev = x
+	yPrev = y
+	for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
+		yPrev--
+		piece = b.getPiece(xPrev, yPrev)
+		if piece != nil {
+			if piece.Name == Rook && piece.Color == b.turn {
+				b.tiles[xPrev][yPrev] = nil
+				b.tiles[x][y] = piece
+				return nil
+			} else {
+				break
+			}
+		}
+	}
+
+	xPrev = x
+	yPrev = y
+	for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
+		xPrev--
+		piece = b.getPiece(xPrev, yPrev)
+		if piece != nil {
+			if piece.Name == Rook && piece.Color == b.turn {
+				b.tiles[xPrev][yPrev] = nil
+				b.tiles[x][y] = piece
+				return nil
+			} else {
+				break
+			}
+		}
+	}
+
+	xPrev = x
+	yPrev = y
+	for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
+		yPrev++
+		piece = b.getPiece(xPrev, yPrev)
+		if piece != nil {
+			if piece.Name == Rook && piece.Color == b.turn {
+				b.tiles[xPrev][yPrev] = nil
+				b.tiles[x][y] = piece
+				return nil
+			} else {
+				break
+			}
+		}
+	}
+
+	return fmt.Errorf("no rook found that can move to %s", position)
 }
 
 func (b *Board) moveBishop(position string) error {

chess/board_test.go

@@ -130,6 +130,27 @@ func TestBoardMoveBishop(t *testing.T) {
 	assertNoPiece(t, b, "f8")
 }
 
+func TestBoardMoveRook(t *testing.T) {
+	b := chess.NewBoard()
+
+	b.Move("Ra3")
+
+	assertMoveError(t, b, "Ra3", "no rook found that can move to a3")
+
+	b.Move("a4")
+	b.Move("a5")
+
+	b.Move("Ra3")
+
+	assertPiece(t, b, "a3", chess.Rook, chess.Light)
+	assertNoPiece(t, b, "a1")
+
+	b.Move("Ra6")
+
+	assertPiece(t, b, "a6", chess.Rook, chess.Dark)
+	assertNoPiece(t, b, "a8")
+}
+
 func assertPiece(t *testing.T, b *chess.Board, position string, name chess.PieceName, color chess.Color) {
 	p := b.At(position)