cau-praktikum/app/chess_sim/test.py

from enum import Enum, auto
from dataclasses import dataclass
from typing import Iterator, Optional, List, Tuple
import random
from game_board import ChessBoard, MoveType, Color, PieceType, BoardMove, BoardPos


def play_random_game(board: Optional[ChessBoard] = None, max_moves: int = 400, verbose: bool = False) -> Tuple[ ChessBoard, int]:
    if board is None:
        board = ChessBoard.init_default()

    current = Color.WHITE  # white moves first
    moves_played = 0

    while moves_played < max_moves:
        legal = board.generate_moves(current)
        if not legal:
            # no legal moves
            if verbose:
                print(f"no legal moves for {current.name} after {moves_played} moves")
            return  board, moves_played

        # prefer castling for debugging
        castling_moves = [
            m for m in legal
            if m.move_type in (MoveType.CASTLING_KINGSIDE, MoveType.CASTLING_QUEENSIDE)
        ]
        if castling_moves:
            move = castling_moves[0]
        else:
            move = random.choice(legal)
        ok = board.make_move(move, current)
        # debug assert
        if not ok:
            if verbose:
                print(f"make_move returned False for move {move} by {current}")
            return  board, moves_played
        moves_played += 1
        if verbose:
            print(f"{moves_played:03d}: {current.name} played {move}\nboard:\n{board}")

        # check whether the captured piece was a king
        _, captured = board.move_history[-1]
        if captured is not None and captured.type == PieceType.KING:
            if verbose:
                print(f"king captured by {current.name} on move {moves_played}.")
                raise RuntimeWarning("this should not be possible")
            return  board, moves_played

        current = current.opposite

    if verbose:
        print(f"reached move limit ({max_moves})")
    return  board, moves_played


def run_random_games(n: int = 20, max_moves: int = 200, verbose: bool = False):
    for i in range(n):
        final_board, moves = play_random_game(None, max_moves=max_moves, verbose=verbose)
        if verbose:
            print(f"game {i+1}: moves={moves}\nfinal_board:\n{final_board}")
    return 


def test_castling_kingside_both_sides():
    board = ChessBoard.init_default()

    # rewrite with  boardmove from string
    seq = [
        (BoardMove(BoardPos((7, 6)), BoardPos((5, 5))), Color.WHITE),
        (BoardMove(BoardPos((0, 1)), BoardPos((2, 2))), Color.BLACK),
        # clear white pawn allows bishop moving
        (BoardMove(BoardPos((6, 6)), BoardPos((5, 6))), Color.WHITE),
        # move bishop
        (BoardMove(BoardPos((0, 6)), BoardPos((2, 5))), Color.BLACK),
        (BoardMove(BoardPos((7, 5)), BoardPos((5, 7))), Color.WHITE),
        # clear black pawn for bishop 
        (BoardMove(BoardPos((1, 4)), BoardPos((2, 4))), Color.BLACK),
        # moving black bishop
        (BoardMove(BoardPos((0, 5)), BoardPos((1, 4))), Color.BLACK),


        # white castle kingside
        (BoardMove(BoardPos((7, 4)), BoardPos((7, 6)), MoveType.CASTLING_KINGSIDE), Color.WHITE),
        # black castle kingside
        (BoardMove(BoardPos((0, 4)), BoardPos((0, 6)), MoveType.CASTLING_KINGSIDE), Color.BLACK),
    ]

    for move, color in seq:
        ok = board.make_move(move, color)
        assert ok, f"move {move} by {color} failed unexpectedly on board:\n{board}"

    # validate castle 
    wk = board.pos_of_king(Color.WHITE)
    assert wk == BoardPos((7, 6)), f"white king expected at (7,6), found {wk}"
    wf = board.fields[7][5].piece
    assert wf is not None and wf.type == PieceType.ROOK and wf.color == Color.WHITE, "white rook not on f1 after castling"

    bk = board.pos_of_king(Color.BLACK)
    assert bk == BoardPos((0, 6)), f"black king expected at (0,6), found {bk}"
    bf = board.fields[0][5].piece
    assert bf is not None and bf.type == PieceType.ROOK and bf.color == Color.BLACK, "black rook not on f8 after castling"

    print("test_castling_kingside_both_sides: passed")

# used only for testing purposes
def main(): 
    default_brd = ChessBoard.init_default()
    default_brd.generate_moves

    # standardized expected string for initial position
    expected_start = (
        "rnbqkbnr\n"
        "pppppppp\n"
        "........\n"
        "........\n"
        "........\n"
        "........\n"
        "PPPPPPPP\n"
        "RNBQKBNR"
    )

    # test string representation of board
    actual_start = str(default_brd)
    if actual_start != expected_start:
        raise AssertionError(f"initial board mismatch:\nexpected:\n{expected_start}\n\nactual:\n{actual_start}")

    # test num moves
    mvs = default_brd.moves_unfiltered(Color.BLACK)
    expected_move_count = 20  # 16 pawn moves and 4 knight
    if len(mvs) != expected_move_count:
        raise AssertionError(f"initial move count for black mismatch: expected {expected_move_count}, got {len(mvs)}")
    

    mvs = default_brd.moves_unfiltered(Color.WHITE)
    expected_move_count = 20  # 16 pawn moves and 4 knight
    if len(mvs) != expected_move_count:
        raise AssertionError(f"Initial move count for white mismatch: expected {expected_move_count}, got {len(mvs)}")
    
    test_castling_kingside_both_sides()
    run_random_games(verbose=False)

    board = ChessBoard.init_default()
    # helper to create boardmove from two-square string
    def bm(s):
        return BoardMove(
            ChessBoard.algebraic_to_pos(s[0:2]),
            ChessBoard.algebraic_to_pos(s[2:4])
        )

    # perform four cycles of the knight shuffle
    # Nf3-Nf6-Ng1-Ng8 and returns to the starting position.
    seq = []
    for _ in range(4):
        seq.extend([
            (bm("g1f3"), Color.WHITE),
            (bm("g8f6"), Color.BLACK),
            (bm("f3g1"), Color.WHITE),
            (bm("f6g8"), Color.BLACK),
        ])
    for move, color in seq:
        ok = board.make_move(move, color)
        assert ok, "repetition test move failed"

    rep = board.highest_repetiton_amount()
    assert rep >= 5, f"expected at least 5 repetitions, got {rep}"
    assert board.is_fivefold_repetition(), "board should report fivefold repetition"

    print(f"all tests passed")


if __name__ == '__main__':
    main()