_CoroGuard cannot be awaited

[litwisha]

Long story short

1. _CoroGuard class has no implementation for __await__ method, only __iter__.
   That's why_CoroGuard instance cannot be awaited, just yielded from.

2. Fix warning message for ClientSession.close() method

Expected behaviour

• _CoroGuard can be awaited

Actual behaviour

• _CoroGuard cannot be awaited

Steps to reproduce

#!/usr/bin/env python
import aiohttp
import asyncio


async def coro_function(loop):
    session = aiohttp.ClientSession(loop=loop)
    await session.close()


if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    try:
        loop.run_until_complete(coro_function(loop))
    finally:
        loop.close()

Your environment

OS X 10.12.3
python 3.6.0
aiohttp==2.2.0

[hellysmile]

Why it should produce warning if not awaited/yield from? Seems starting aiohttp 2.0+ close is synchronous method, previously it was returning empty future.

[asvetlov]

@hellysmile

It's still asynchronous but I want to stress people and force them to use await session.close() during migration period.

The method still returns empty future but will be replaced with pure coroutine eventually.

[asvetlov]

Closed by #2027

[lock]

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