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chess/test/test_movegen.py
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Add bishop move gen tests
2025-08-17 19:12:16 -04:00

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8.3 KiB
Python

import ctypes
from test.base import ChessLibTestBase
from test.chess_ffi import gen_white_pawn_quiet_pushes
from test.chess_ffi import gen_white_pawn_push_promotions
from test.chess_ffi import gen_white_pawn_capture_promotions
from test.chess_ffi import gen_white_pawn_captures
from test.chess_ffi import gen_knight_moves
from test.chess_ffi import gen_bishop_moves
from test.chess_ffi import Move
from test.chess_ffi import Board
MAX_MOVES = 256
class TestPseudoMoveGeneration(ChessLibTestBase):
def test_knight_move_gen(self):
all_move_types = [
("8/8/8/8/3N4/8/8/8 w - - 0 1", 8, "center d4: 8 moves"),
("8/8/8/8/N7/8/8/8 w - - 0 1", 4, "edge a4: 4 moves"),
("8/8/8/8/8/8/8/N7 w - - 0 1", 2, "corner a1: 2 moves"),
("8/8/8/8/8/8/8/1N6 w - - 0 1", 3, "b1: 3 moves"),
# own pieces on destinations reduce count
("8/8/8/5P2/3N4/1P6/2P5/8 w - - 0 1", 5, "d4 with own pawns on f5,b3,c2 -> 8-3=5"),
# two knights
("8/8/8/8/8/8/8/1N4N1 w - - 0 1", 6, "b1 & g1, empty board: 3+3"),
# all 8 destinations occupied by black (still 8 total moves, all as captures)
("8/8/2p1p3/1p3p2/3N4/1p3p2/2p1p3/8 w - - 0 1", 8, "enemy on all 8 targets"),
# corner with one capture and one friendly block
("8/8/8/8/8/1p6/2P5/N7 w - - 0 1", 1, "a1, b3 black (capture), c2 white (blocked)"),
]
captures_only = False
for fen, expected, msg in all_move_types:
with self.subTest(msg=msg, fen=fen):
cnt = ctypes.c_int(0)
moves = (Move * MAX_MOVES)()
b = Board()
self.load_fen(fen, board=b)
gen_knight_moves(b, moves, ctypes.byref(cnt), captures_only)
self.assertEqual(expected, cnt.value)
cases_knight_captures = [
("8/8/8/8/3N4/8/8/8 w - - 0 1", 0, "center d4 but no enemies"),
("8/8/2p5/1p6/3N4/5p2/8/8 w - - 0 1", 3, "d4 capturing c6,b5,f3"),
("8/8/8/8/3N4/1P3p2/4P3/8 w - - 0 1", 1, "d4 with f3 black (1 cap), b3/e2 white (not capturable)"),
("8/8/2p1p3/1p3p2/3N4/1p3p2/2p1p3/8 w - - 0 1", 8, "d4 with all 8 targets black: 8 captures"),
]
captures_only = True
for fen, expected, msg in cases_knight_captures:
with self.subTest(msg=msg, fen=fen):
cnt = ctypes.c_int(0)
moves = (Move * MAX_MOVES)()
b = Board()
self.load_fen(fen, board=b)
gen_knight_moves(b, moves, ctypes.byref(cnt), captures_only)
self.assertEqual(expected, cnt.value)
def test_bishop_move_gen(self):
cases_bishop_all = [
("8/8/8/8/3B4/8/8/8 w - - 0 1", 13, "center d4: 13 moves"),
("8/8/8/8/B7/8/8/8 w - - 0 1", 7, "edge a4: 7 moves"),
("8/8/8/8/8/8/8/B7 w - - 0 1", 7, "corner a1: 7 moves"),
("8/8/8/8/8/8/8/1B6 w - - 0 1", 7, "b1: 7 moves"),
# all four diagonals blocked immediately by own pieces -> 0
("8/8/8/2P1P3/3B4/2P1P3/8/8 w - - 0 1", 0, "d4 with white pawns on c3,e3,c5,e5"),
# all four diagonals have a black piece on the first square -> 4 (all captures)
("8/8/8/2p1p3/3B4/2p1p3/8/8 w - - 0 1", 4, "d4 with black pawns on c3,e3,c5,e5"),
# mixed blockers: NE own on f6, SW capture on b2, SE capture on e3, NW open
("8/8/1p3P2/8/3B4/4p3/1p6/8 w - - 0 1", 6, ""),
]
captures_only = False
for fen, expected, msg in cases_bishop_all:
with self.subTest(msg=msg, fen=fen):
cnt = ctypes.c_int(0)
moves = (Move * MAX_MOVES)()
b = Board()
self.load_fen(fen, board=b)
gen_bishop_moves(b, moves, ctypes.byref(cnt), captures_only)
self.assertEqual(expected, cnt.value)
cases_bishop_caps = [
("8/8/8/8/3B4/8/8/8 w - - 0 1", 0, "no enemies to capture"),
# first squares on all rays are enemies → 4 captures
("8/8/8/2p1p3/3B4/2p1p3/8/8 w - - 0 1", 4, "adjacent caps on c3,e3,c5,e5"),
# enemies at far ends on each ray → still 4 captures (one per ray)
("7p/p7/8/8/3B4/8/8/p5p1 w - - 0 1", 4, "targets h8,a7,g1,a1"),
# mixed: only two rays have a capture
("8/8/1p3P2/8/3B4/2P5/5p2/8 w - - 0 1", 2, "d4: NW capture b6, SE capture f2; NE/SW blocked by own"),
]
captures_only = True
for fen, expected, msg in cases_bishop_caps:
with self.subTest(msg=msg, fen=fen):
cnt = ctypes.c_int(0)
moves = (Move * MAX_MOVES)()
b = Board()
self.load_fen(fen, board=b)
gen_bishop_moves(b, moves, ctypes.byref(cnt), captures_only)
self.assertEqual(expected, cnt.value)
def test_rook_move_gen(self):
pass
def test_queen_move_gen(self):
pass
def test_king_move_gen(self):
pass
def test_quiet_pawn_pushes_white(self):
cases = [
("8/pppppppp/8/8/8/8/PPPPPPPP/8 w - - 0 1", 16, "open ranks"),
("8/8/8/8/8/8/P7/8 w - - 0 1", 2, "single pawn open"),
("8/8/8/8/8/p7/P7/8 w - - 0 1", 0, "blocked single enemy"),
("8/8/8/8/8/n7/P7/8 w - - 0 1", 0, "blocked single friendly"),
# Although legal move, we have a separate function that calculates this move type.
("8/9P/8/8/8/8/8/8 w - - 0 1", 0, "no promotion push"),
]
for fen, expected, msg in cases:
with self.subTest(msg=msg, fen=fen):
cnt = ctypes.c_int(0)
moves = (Move * MAX_MOVES)()
b = Board()
self.load_fen(fen, board=b)
gen_white_pawn_quiet_pushes(b, moves, ctypes.byref(cnt))
self.assertEqual(expected, cnt.value)
def test_quiet_pawn_promotions_white(self):
cases = [
("8/PPPPPPPP/8/8/8/8/8/8 w - - 0 1", 8, "all open on 7th rank"),
("8/8/7P/8/8/8/8/8 w - - 0 1", 0, "no promotions"),
("7n/7P/8/8/8/8/8/8 w - - 0 1", 0, "blocked by enemy"),
("7N/7P/8/8/8/8/8/8 w - - 0 1", 0, "blocked by friendly"),
]
for fen, expected, msg in cases:
with self.subTest(msg=msg, fen=fen):
cnt = ctypes.c_int(0)
moves = (Move * MAX_MOVES)()
b = Board()
self.load_fen(fen, board=b)
gen_white_pawn_push_promotions(b, moves, ctypes.byref(cnt))
self.assertEqual(expected, cnt.value)
def test_capture_pawn_promotions_white(self):
cases = [
("6n1/7P/8/8/8/8/8/8 w - - 0 1", 1, "one capture"),
("5n1n/6P1/8/8/8/8/8/8 w - - 0 1", 2, "two captures"),
("8/7P/8/8/8/8/8/8 w - - 0 1", 0, "no capture"),
]
for fen, expected, msg in cases:
with self.subTest(msg=msg, fen=fen):
cnt = ctypes.c_int(0)
moves = (Move * MAX_MOVES)()
b = Board()
self.load_fen(fen, board=b)
gen_white_pawn_capture_promotions(b, moves, ctypes.byref(cnt))
self.assertEqual(expected, cnt.value)
def test_capture_pawn_white(self):
cases = [
# normal diagonal captures
("8/8/8/3n4/4P3/8/8/8 w - - 0 1", 1, "e4xd5"),
("8/8/8/3n1n2/4P3/8/8/8 w - - 0 1", 2, "e4xd5 and e4xf5"),
("8/8/8/1p6/P7/8/8/8 w - - 0 1", 1, "edge file: a4xb5"),
("8/7P/8/8/8/8/8/8 w - - 0 1", 0, "no capture"),
# en passant
("8/8/8/3pP3/8/8/8/8 w - d6 0 1", 1, "EP available: e5xd6 e.p. (black pawn on d5)"),
("8/8/5n2/3pP3/8/8/8/8 w - d6 0 1", 2, "EP e5xd6 and normal e5xf6"),
("8/8/8/3p4/8/4P3/8/8 w - d6 0 1", 0, "EP square present but no white pawn can take"),
]
for fen, expected, msg in cases:
with self.subTest(msg=msg, fen=fen):
cnt = ctypes.c_int(0)
moves = (Move * MAX_MOVES)()
b = Board()
self.load_fen(fen, board=b)
gen_white_pawn_captures(b, moves, ctypes.byref(cnt))
self.assertEqual(expected, cnt.value)