ruff/crates/ty_python_semantic/resources/mdtest/with/async.md

Async with statements

Basic async with statement

The type of the target variable in a with statement should be the return type from the context manager's __aenter__ method. However, async with statements aren't supported yet. This test asserts that it doesn't emit any context manager-related errors.

class Target: ...

class Manager:
    async def __aenter__(self) -> Target:
        return Target()

    async def __aexit__(self, exc_type, exc_value, traceback): ...

async def test():
    async with Manager() as f:
        reveal_type(f)  # revealed: Target

Multiple targets

class Manager:
    async def __aenter__(self) -> tuple[int, str]:
        return 42, "hello"

    async def __aexit__(self, exc_type, exc_value, traceback): ...

async def test():
    async with Manager() as (x, y):
        reveal_type(x)  # revealed: int
        reveal_type(y)  # revealed: str

@asynccontextmanager

from contextlib import asynccontextmanager
from typing import AsyncGenerator

class Session: ...

@asynccontextmanager
async def connect() -> AsyncGenerator[Session]:
    yield Session()

# TODO: this should be `() -> _AsyncGeneratorContextManager[Session, None]`
reveal_type(connect)  # revealed: (...) -> _AsyncGeneratorContextManager[Unknown, None]

async def main():
    async with connect() as session:
        # TODO: should be `Session`
        reveal_type(session)  # revealed: Unknown

asyncio.timeout

[environment]
python-version = "3.11"

import asyncio

async def long_running_task():
    await asyncio.sleep(5)

async def main():
    async with asyncio.timeout(1):
        await long_running_task()

asyncio.TaskGroup

[environment]
python-version = "3.11"

import asyncio

async def long_running_task():
    await asyncio.sleep(5)

async def main():
    async with asyncio.TaskGroup() as tg:
        # TODO: should be `TaskGroup`
        reveal_type(tg)  # revealed: Unknown

        tg.create_task(long_running_task())