Add simple pawn move + tests

chess/board.go

@@ -7,14 +7,16 @@ import (
 	"image/png"
 	"log"
 	"os"
+	"strings"
 )
 
 type Board struct {
 	tiles [8][8]*Piece
+	turn  Color
 }
 
 func NewBoard() *Board {
-	board := &Board{}
+	board := &Board{turn: Light}
 
 	board.mustSetPiece(Rook, Light, "a1")
 	board.mustSetPiece(Knight, Light, "b1")
@@ -112,12 +114,100 @@ func (b *Board) SetPiece(name PieceName, color Color, position string) error {
 	return nil
 }
 
+func (b *Board) Parse(pgn string) error {
+	var (
+		moves = strings.Split(pgn, " ")
+		err   error
+	)
+
+	for _, move := range moves {
+		if err = b.Move(move); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (b *Board) Move(position string) error {
+	var (
+		name PieceName
+		err  error
+	)
+
+	// TODO: implement remaining moveset of pieces
+	if len(position) == 2 {
+		name = Pawn
+	}
+
+	switch name {
+	case Pawn:
+		err = b.movePawn(position)
+	default:
+		err = fmt.Errorf("invalid move: %s", position)
+	}
+
+	if err != nil {
+		return err
+	}
+
+	if b.turn == Light {
+		b.turn = Dark
+	} else {
+		b.turn = Light
+	}
+
+	return nil
+}
+
+func (b *Board) movePawn(position string) error {
+	var (
+		x     int
+		y     int
+		piece *Piece
+		err   error
+	)
+
+	if x, y, err = getXY(position); err != nil {
+		return err
+	}
+
+	// TODO: implement diagonal pawn attacks
+
+	for yi := 0; yi < 8; yi++ {
+		piece = b.tiles[x][yi]
+		if piece != nil && piece.Name == Pawn && piece.Color == b.turn {
+			// TODO: assert move is valid:
+			// * 2 moves from start position
+			// * 1 move otherwise
+			// * diagonal if attacking
+			b.tiles[x][y] = piece
+			b.tiles[x][yi] = nil
+			return nil
+		}
+	}
+
+	return nil
+}
+
 func (b *Board) mustSetPiece(name PieceName, color Color, position string) {
 	if err := b.SetPiece(name, color, position); err != nil {
 		log.Fatalf("cannot set piece %s: %v", name, err)
 	}
 }
 
+func (b *Board) At(position string) *Piece {
+	var (
+		x   int
+		y   int
+		err error
+	)
+	if x, y, err = getXY(position); err != nil {
+		return nil
+	}
+	return b.tiles[x][y]
+}
+
 func getXY(position string) (int, int, error) {
 	var (
 		posX rune

chess/board_test.go

@@ -0,0 +1,93 @@
+package chess_test
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"testing"
+
+	"github.com/ekzyis/sn-chess/chess"
+	"github.com/stretchr/testify/assert"
+)
+
+func init() {
+	// change working directory to the root of the project
+	// so assets/ can be found
+	wd, _ := os.Getwd()
+	os.Chdir(path.Dir(wd))
+}
+
+func TestBoardInitial(t *testing.T) {
+	b := chess.NewBoard()
+
+	assertPiece(t, b, "a1", chess.Rook, chess.Light)
+	assertPiece(t, b, "b1", chess.Knight, chess.Light)
+	assertPiece(t, b, "c1", chess.Bishop, chess.Light)
+	assertPiece(t, b, "d1", chess.Queen, chess.Light)
+	assertPiece(t, b, "e1", chess.King, chess.Light)
+	assertPiece(t, b, "f1", chess.Bishop, chess.Light)
+	assertPiece(t, b, "g1", chess.Knight, chess.Light)
+	assertPiece(t, b, "h1", chess.Rook, chess.Light)
+
+	assertPiece(t, b, "a2", chess.Pawn, chess.Light)
+	assertPiece(t, b, "b2", chess.Pawn, chess.Light)
+	assertPiece(t, b, "c2", chess.Pawn, chess.Light)
+	assertPiece(t, b, "d2", chess.Pawn, chess.Light)
+	assertPiece(t, b, "e2", chess.Pawn, chess.Light)
+	assertPiece(t, b, "f2", chess.Pawn, chess.Light)
+	assertPiece(t, b, "g2", chess.Pawn, chess.Light)
+	assertPiece(t, b, "h2", chess.Pawn, chess.Light)
+
+	assertPiece(t, b, "a8", chess.Rook, chess.Dark)
+	assertPiece(t, b, "b8", chess.Knight, chess.Dark)
+	assertPiece(t, b, "c8", chess.Bishop, chess.Dark)
+	assertPiece(t, b, "d8", chess.Queen, chess.Dark)
+	assertPiece(t, b, "e8", chess.King, chess.Dark)
+	assertPiece(t, b, "f8", chess.Bishop, chess.Dark)
+	assertPiece(t, b, "g8", chess.Knight, chess.Dark)
+	assertPiece(t, b, "h8", chess.Rook, chess.Dark)
+
+	assertPiece(t, b, "a7", chess.Pawn, chess.Dark)
+	assertPiece(t, b, "b7", chess.Pawn, chess.Dark)
+	assertPiece(t, b, "c7", chess.Pawn, chess.Dark)
+	assertPiece(t, b, "d7", chess.Pawn, chess.Dark)
+	assertPiece(t, b, "e7", chess.Pawn, chess.Dark)
+	assertPiece(t, b, "f7", chess.Pawn, chess.Dark)
+	assertPiece(t, b, "g7", chess.Pawn, chess.Dark)
+	assertPiece(t, b, "h7", chess.Pawn, chess.Dark)
+}
+
+func TestBoardMovePawn(t *testing.T) {
+	b := chess.NewBoard()
+
+	b.Move("e4")
+
+	assertNoPiece(t, b, "e2")
+	assertPiece(t, b, "e4", chess.Pawn, chess.Light)
+
+	b.Move("e5")
+
+	assertNoPiece(t, b, "e7")
+	assertPiece(t, b, "e5", chess.Pawn, chess.Dark)
+}
+
+func assertPiece(t *testing.T, b *chess.Board, position string, name chess.PieceName, color chess.Color) {
+	p := b.At(position)
+
+	c := "white"
+	if color == chess.Dark {
+		c = "black"
+	}
+
+	msg := fmt.Sprintf("expected %s %s at %s", c, name, position)
+
+	assert.NotNil(t, p, msg)
+	assert.Equal(t, name, p.Name, msg)
+	assert.Equal(t, color, p.Color, msg)
+}
+
+func assertNoPiece(t *testing.T, b *chess.Board, position string) {
+	p := b.At(position)
+
+	assert.Nil(t, p, "expected no piece at %s", position)
+}

go.mod

@@ -2,4 +2,13 @@ module github.com/ekzyis/sn-chess
 
 go 1.23.0
 
-require golang.org/x/image v0.20.0
+require (
+	github.com/stretchr/testify v1.9.0
+	golang.org/x/image v0.20.0
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -1,2 +1,12 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 golang.org/x/image v0.20.0 h1:7cVCUjQwfL18gyBJOmYvptfSHS8Fb3YUDtfLIZ7Nbpw=
 golang.org/x/image v0.20.0/go.mod h1:0a88To4CYVBAHp5FXJm8o7QbUl37Vd85ply1vyD8auM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=