Select initial value is not set via parameter

[mzebrak]

Consider such a test:

def test_select() -> None:
    # ARRANGE
    expected_value: Final[int] = 1

    # ACT
    select = Select(options=[(str(expected_value), expected_value)], value=expected_value)

    # ASSERT
    assert select.value == expected_value

it is failing because:

        # ASSERT
>       assert select.value == expected_value
E       assert None == 1
E        +  where None = Select().value

[davep]

Like a few things within Textual, the value of the Select will only settle on a correct value once a DOM is available and the widget is fully mounted. It would be normal to test the working of the various widgets using App.run_test. For example:

from textual.app import App, ComposeResult
from textual.widgets import Select

class SelectApp(App[None]):

    INITIAL_VALUE = 3

    def compose(self) -> ComposeResult:
        yield Select[int]([(str(n), n) for n in range(10)], value=self.INITIAL_VALUE)

async def test_select_initial_value():
    async with SelectApp().run_test() as pilot:
        assert pilot.app.query_one(Select).value == SelectApp.INITIAL_VALUE

[mzebrak]

This originates from the fact I have a thin wrapper around Select - If there is just a single option, there is nothing to select from, so just a Static is presented with that option, and with >=2 options Select is presented.. So you suggest that it has to be mounted. I'll try mounting it in the wrapper widget, thanks.