Bug in sliding puzzle game

[TomJGooding]

Obviously this isn't high priority, but I discovered a bug in the sliding puzzle game in the Textual demo, where the solution seems to be off by one tile.

Here's a screenshot of an apparently solved 5x5 puzzle, but the tile containing the "ll" of "cell" is still in the wrong place.

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[TomJGooding]

Maybe fixed by #5762?

[willmcgugan]

It might be! I think we just need a test. I do remember that PR. It just never seemed enough of a priority to look into.

[TomJGooding]

I spent far too long just trying to solve the 5x5 puzzle, let alone debugging the code as well!

I'll try to remember to look at this again in the new year, but it looks like the problem is the initial shuffle:

from textual import work
from textual.app import App, ComposeResult
from textual.demo.game import LEVELS, Game
from textual.widgets import Footer


class MockGame(Game):
    @work(exclusive=True)
    async def shuffle(self, shuffles: int = 1) -> None:
        """Override the default to perform only a single shuffle."""
        super().shuffle(shuffles)


class GameApp(App):
    BINDINGS = [("n", "new_game", "New Game")]

    def compose(self) -> ComposeResult:
        game = MockGame(
            LEVELS["Python"],
            "",  # Prevent the shuffle on L387
            dimensions=(3, 3),
            tile_size=(16, 8),
        )
        game.visible = True
        yield game
        yield Footer()

    async def action_new_game(self) -> None:
        game = self.query_one(Game)
        game.state = "waiting"
        game.language = "Python"
        await game.recompose()
        game.focus()


if __name__ == "__main__":
    app = GameApp()
    app.run()