Add enpassant rules to getCapturesInOrder

Author: ArcticXWolf

game/game.go

@@ -3,6 +3,7 @@ package game
 import (
 	"errors"
 	"math/bits"
+	"reflect"
 
 	"github.com/dylhunn/dragontoothmg"
 )
@@ -226,3 +227,12 @@ func (g *Game) PopMove() error {
 
 	return nil
 }
+
+func (g *Game) GetEnPassentSquare() uint8 {
+	value := reflect.ValueOf(g.Position).Elem().FieldByName("enpassant")
+	if value.Kind() != reflect.Uint8 {
+		return 0
+	}
+
+	return uint8(value.Uint())
+}

game/game_test.go

@@ -105,3 +105,23 @@ func TestPopNoMoves(t *testing.T) {
 		t.Errorf("PopNoMoves = %v, is not an error", err)
 	}
 }
+
+func TestGame_GetEnPassentSquare(t *testing.T) {
+	tests := []struct {
+		name string
+		game *Game
+		want uint8
+	}{
+		{"Startposition", New(), 0},
+		{"On c6", NewFromFen("rnbqkbnr/pp3ppp/3p4/2pPp3/4P3/8/PPP2PPP/RNBQKBNR w KQkq c6 0 41"), 42},
+		{"On b3", NewFromFen("rnbqkbnr/pp3ppp/3p4/3Pp3/1Pp1P3/5P2/P1P3PP/RNBQKBNR b KQkq b3 0 5"), 17},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+
+			if got := tt.game.GetEnPassentSquare(); got != tt.want {
+				t.Errorf("Game.GetEnPassentSquare() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

search/search.go

@@ -339,7 +339,7 @@ func (s *Search) getCapturesInOrder() []dragontoothmg.Move {
 	}
 
 	for _, move := range s.Game.Position.GenerateLegalMoves() {
-		if bitboardsOpponent.All&(1<<move.To()) > 0 {
+		if isCaptureOrPromotionMove(s.Game, move) {
 			captures = append(captures, move)
 		}
 	}

search/search_test.go

@@ -90,10 +90,6 @@ func BenchmarkSearchFullEvaluation9(b *testing.B)  { benchmarkSearchFullEvaluati
 func BenchmarkSearchFullEvaluation10(b *testing.B) { benchmarkSearchFullEvaluation(10, b) }
 func BenchmarkSearchFullEvaluation11(b *testing.B) { benchmarkSearchFullEvaluation(11, b) }
 
-func getMove(moveStr string) dragontoothmg.Move {
-	move, _ := dragontoothmg.ParseMove(moveStr)
-	return move
-}
 func TestSearch_SearchBestMove(t *testing.T) {
 	type fields struct {
 		Game                   *game.Game

search/utils.go

@@ -5,21 +5,27 @@ import (
 	"go.janniklasrichter.de/axwchessbot/game"
 )
 
+func getMove(moveStr string) dragontoothmg.Move {
+	move, _ := dragontoothmg.ParseMove(moveStr)
+	return move
+}
+
 func (s *Search) getCaptureMVVLVA(move dragontoothmg.Move, bitboardsOwn dragontoothmg.Bitboards, bitboardsOpponent dragontoothmg.Bitboards) (score int) {
 	pieceTypeFrom, _ := getPieceTypeAtPosition(move.From(), bitboardsOwn)
 	pieceTypeTo, _ := getPieceTypeAtPosition(move.To(), bitboardsOpponent)
 
 	return (1200 - s.evaluationProvider.GetPieceTypeValue(pieceTypeTo)) + int(pieceTypeFrom)
 }
 
-// TODO: No en_passent_rules checked yet!
 func isCaptureOrPromotionMove(game *game.Game, move dragontoothmg.Move) bool {
+	bitboardsOwn := game.Position.White
 	bitboardsOpponent := game.Position.Black
 	if !game.Position.Wtomove {
+		bitboardsOwn = game.Position.Black
 		bitboardsOpponent = game.Position.White
 	}
 
-	return bitboardsOpponent.All&(1<<move.To()) > 0 || move.Promote() > 0
+	return bitboardsOpponent.All&(1<<move.To()) > 0 || move.Promote() > 0 || (bitboardsOwn.Pawns&(1<<move.From()) > 0 && game.GetEnPassentSquare() == move.To())
 }
 
 func getPieceTypeAtPosition(position uint8, bitboards dragontoothmg.Bitboards) (pieceType dragontoothmg.Piece, occupied bool) {

search/utils_test.go

@@ -0,0 +1,30 @@
+package search
+
+import (
+	"testing"
+
+	"github.com/dylhunn/dragontoothmg"
+	"go.janniklasrichter.de/axwchessbot/game"
+)
+
+func Test_isCaptureOrPromotionMove(t *testing.T) {
+	type args struct {
+		game *game.Game
+		move dragontoothmg.Move
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{"En Passant", args{game.NewFromFen("rnbqkbnr/pp3ppp/3p4/3Pp3/1Pp1P3/5P2/P1P3PP/RNBQKBNR b KQkq b3 0 5"), getMove("c4b3")}, true},
+		{"Missed En Passant", args{game.NewFromFen("rnbqkbnr/pp4pp/3p1p2/3Pp3/1Pp1P3/5P1N/P1P3PP/RNBQKB1R b KQkq - 1 6"), getMove("c4b3")}, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := isCaptureOrPromotionMove(tt.args.game, tt.args.move); got != tt.want {
+				t.Errorf("isCaptureOrPromotionMove() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}