async def METHOD_NAME(self, i18n: I18n):
    dp = Dispatcher()
    middleware = SimpleI18nMiddleware(i18n=i18n)
    middleware.setup(router=dp)
    locale = await middleware.get_locale(
        None,
        {
            "event_from_user": User(
                id=42,
                is_bot=False,
                first_name="Test",
                language_code="unknown",
            )
        },
    )
    assert locale == i18n.default_locale