App.on_unmount is called twice when running via pilot (App.run_test)

[mzebrak]

Textual version: 0.36.0

There seems to be an issue with pilot causing on_unmount to be called twice.
Consider the following code:

import asyncio

from textual.app import App

UNMOUNT_TIMES = 0


async def test_on_unmount_is_called_once() -> None:
    class MyApp(App[None]):

        def on_unmount(self) -> None:
            global UNMOUNT_TIMES
            UNMOUNT_TIMES += 1

    async with MyApp().run_test():
        pass

    assert UNMOUNT_TIMES == 1, f"App.on_unmount should be called once, but it was called {UNMOUNT_TIMES} times"


if __name__ == "__main__":
    asyncio.run(test_on_unmount_is_called_once())

It results with AssertionError.

While this one is correct:

import asyncio

from textual.app import App, ComposeResult
from textual.binding import Binding
from textual.widgets import Footer

UNMOUNT_TIMES = 0


class MyApp(App[None]):
    BINDINGS = [
        Binding("q", "exit", "Exit"),
    ]

    def compose(self) -> ComposeResult:
        yield Footer()

    def on_unmount(self) -> None:
        global UNMOUNT_TIMES
        UNMOUNT_TIMES += 1

    def action_exit(self) -> None:
        self.exit()


if __name__ == "__main__":
    MyApp().run()
    assert UNMOUNT_TIMES == 1, f"App.on_unmount should be called once, but it was called {UNMOUNT_TIMES} times"

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[mzebrak]

Also I noticed there is a weird execution order.

Consider:

import asyncio
import logging

from textual.app import App

logging.basicConfig(handlers=[logging.StreamHandler()], level=logging.INFO)
logger = logging.getLogger("test")


async def test_on_unmount_ignoring_a_finally_block() -> None:
    class MyApp(App[None]):

        something = False

        def on_mount(self):
            self.something = True

        async def on_unmount(self) -> None:
            await self.close_something()

        async def close_something(self) -> None:
            if self.something:
                logger.info("closing something")
                try:
                    await self.very_slow_cleanup()
                finally:
                    logger.info("setting something to False")
                    self.something = False

        async def very_slow_cleanup(self):
            logger.info("very_slow_cleanup started")
            await asyncio.sleep(2)
            logger.info("very_slow_cleanup finished")

    async with MyApp().run_test():
        pass


if __name__ == "__main__":
    asyncio.run(test_on_unmount_ignoring_a_finally_block())

Now it causes the very_slow_cleanup to run twice because finally block is executed too late and it prints:

INFO:test:closing something
INFO:test:very_slow_cleanup started
INFO:test:closing something
INFO:test:very_slow_cleanup started
INFO:test:very_slow_cleanup finished
INFO:test:setting something to False
INFO:test:very_slow_cleanup finished
INFO:test:setting something to False

while it should be:

INFO:test:closing something
INFO:test:very_slow_cleanup started
INFO:test:very_slow_cleanup finished
INFO:test:setting something to False

[willmcgugan]

Fixed.

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