Merge pull request #50 from tom-anders/fix-perft

Fix en passant bugs in Atomic and Crazyhouse to make perft tests pass

lib/src/position.dart

@@ -54,7 +54,7 @@ abstract class Position {
     Pockets? pockets,
     Side? turn,
     Castles? castles,
-    Square? epSquare,
+    Object? epSquare = _uniqueObjectInstance,
     int? halfmoves,
     int? fullmoves,
     (int, int)? remainingChecks,
@@ -567,10 +567,12 @@ abstract class Position {
         }
 
         final capturedPiece = castlingSide == null
-            ? board.pieceAt(to)
-            : to == epSquare && epCaptureTarget != null
-                ? board.pieceAt(epCaptureTarget)
-                : null;
+            ? (board.pieceAt(to) ??
+                (to == epSquare && epCaptureTarget != null
+                    ? board.pieceAt(epCaptureTarget)
+                    : null))
+            : null;
+
         final isCapture = capturedPiece != null;
 
         if (capturedPiece != null && capturedPiece.role == Role.rook) {
@@ -596,6 +598,7 @@ abstract class Position {
           turn: turn.opposite,
           board: board.setPieceAt(to, Piece(color: turn, role: role)),
           pockets: pockets?.decrement(turn, role),
+          epSquare: null,
         );
     }
   }
@@ -1323,9 +1326,15 @@ abstract class Atomic extends Position {
   /// board.
   @override
   Position playUnchecked(Move move) {
+    if (move is! NormalMove) {
+      return copyWith();
+    }
+
     final castlingSide = _getCastlingSide(move);
     final capturedPiece = castlingSide == null ? board.pieceAt(move.to) : null;
-    final isCapture = capturedPiece != null || move.to == epSquare;
+    final isEnPassant =
+        move.to == epSquare && board.pieceAt(move.from)?.role == Role.pawn;
+    final isCapture = capturedPiece != null || isEnPassant;
     final newPos = super.playUnchecked(move);
 
     if (isCapture) {

test/perft_test.dart

@@ -99,10 +99,10 @@ void main() async {
       }
     }
   });
-  /*
+
   group('Atomic', () {
-    final tests =
-        Parser().parse(File('test/resources/atomic.perft').readAsStringSync());
+    final tests = Parser()
+        .parse(io.File('test/resources/atomic.perft').readAsStringSync());
     for (final perftTest in tests) {
       final position = Atomic.fromSetup(Setup.parseFen(perftTest.fen));
       for (final testCase in perftTest.cases
@@ -115,11 +115,10 @@ void main() async {
       }
     }
   });
-      */
-  /*
+
   group('Crazyhouse', () {
     final tests = Parser()
-        .parse(File('test/resources/crazyhouse.perft').readAsStringSync());
+        .parse(io.File('test/resources/crazyhouse.perft').readAsStringSync());
     for (final perftTest in tests) {
       final position = Crazyhouse.fromSetup(Setup.parseFen(perftTest.fen));
       for (final testCase in perftTest.cases
@@ -132,7 +131,7 @@ void main() async {
       }
     }
   });
-      */
+
   group('Horde', () {
     final tests = Parser()
         .parse(io.File('test/resources/horde.perft').readAsStringSync());

test/position_test.dart

@@ -914,6 +914,14 @@ void main() {
       }
     });
 
+    test('en passant capture', () {
+      final pos = Crazyhouse.fromSetup(Setup.parseFen(
+              'r1bqkbnr/ppppp1pp/2n5/4Pp2/8/8/PPPP1PPP/RNBQKBNR w KQkq f6 0 3'))
+          .play(const NormalMove(from: Square.e5, to: Square.f6));
+      expect(
+          pos.pockets, equals(Pockets.empty.increment(Side.white, Role.pawn)));
+    });
+
     test('parse san', () {
       Position position = Crazyhouse.initial;
       final moves = [