Board.IsDraw() not working in Version 1.17

How to reproduce in version 1.17:

public Move Think(Board board, Timer timer)
{
    // some calculation to find the bestMove (board is fully reset to its original state after this)
    
    board.MakeMove(bestMove);
    if (board.IsDraw())
        Console.WriteLine("ABOUT TO MAKE A MOVE THAT RESULTS IN A DRAW.");
    board.UndoMove(bestMove);

    return bestMove; 
}

Expected behaviour: Whenever the AI makes a move that results in a draw, we should see “ABOUT TO MAKE A MOVE THAT RESULTS IN A DRAW.” in the console

Current behaviour: The debug message never shows up in the console even if the next turn results in a draw. The play-out altorithm catches the draw, but you can’t check for a draw in the Think function. As it is not currently possible to detect a draw, my AIs love spinning in circles and producing one tie after another. 😄

Human error? I’m wondering if there is anything on my end that I might be doing wrong? If you have any ideas, please let me know, but I think the code example shown above is fairly waterproof, right? We should see the debug message if the game is about to result in a draw, but we don’t.

Thanks for having a look! 😃

[LooveToLoose]

One move early makes perfect sense cause the AIs will just keep spinning in circles otherwise anyways. Excellent.

I just tested it out and it now works as expected. So I can confirm that the issues has been resolved! Thanks a lot.

I hope you know how much joy you bring people with this little competition. This is so much fun. I am totally addicted. Haha. Thanks agian. Keep up the great work! ❤️

[SebLague]

Thanks for bringing this to my attention @LooveToLoose, I have just uploaded a patch for this bug. Please note – in case you haven’t seen it in the docs – that you will get the ‘results in draw’ message one move early, but this is intended behaviour in this API:

Note: this function will return true if the same position has occurred twice on the board (rather than 3 times,
which is when the game is actually drawn). This quirk is to help bots avoid repeating positions unnecessarily.