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Multiple kings per color (was_into_check and more affected) #1179

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Multiple kings per color (was_into_check and more affected) #1179

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95383de
fixed multiple kings for was_into_check
winapiadmin Feb 3, 2026
4b0c56d
fixed king() behavior on multiple kings
winapiadmin Feb 3, 2026
c100a37
add test cases (very little)
winapiadmin Feb 3, 2026
08a815d
using the precomputed king mask
winapiadmin Feb 3, 2026
6e0cf05
removed testcase of was_into_check() on multiple kings...
winapiadmin Feb 3, 2026
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2 changes: 1 addition & 1 deletion chess/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -916,7 +916,7 @@ def king(self, color: Color) -> Optional[Square]:
considered.
"""
king_mask = self.occupied_co[color] & self.kings & ~self.promoted
return msb(king_mask) if king_mask else None
return msb(king_mask) if king_mask and popcount(king_mask) == 1 else None

def attacks_mask(self, square: Square) -> Bitboard:
bb_square = BB_SQUARES[square]
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4 changes: 4 additions & 0 deletions test.py
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Expand Up @@ -1720,6 +1720,10 @@ def test_impossible_check_due_to_en_passant(self):
self.assertFalse(board.has_legal_en_passant())
self.assertEqual(len(list(board.legal_moves)), 2)

def test_multiple_kings(self):
board = chess.Board("KKKK1kkk/8/8/8/8/8/8/8 w - - 0 1")
self.assertEqual(board.king(chess.WHITE), None)


class LegalMoveGeneratorTestCase(unittest.TestCase):

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