pytest-dev/pytest-asyncio

There should be a better workaround for event_loop removal and Deprecation of event loop policies in 3.14

Closed this issue · 3 comments

Vizonex commented

Seeing this library and having utilized it with a few of my smaller libraries like aiocallback and aiothreading I want to be able to test asyncio's default loop alongside winloop on windows and uvloop on linux and Apple. Now I know of the event loop policies and all of that but the problem is that it's deprecated in 3.14 with removal coming in 3.16 and I would hate to have to use an uncomfortable hack of my own. I wanted to write a solution that doesn't devolve into bringing back event_loop because it was removed #1106 and I think keeping the warning's mouth shut about is a bad approach. So here's what I wanted to bring to the table hence why I am throwing this issue about it first.

Solution

I see fit to make a new autouse fixure for making use of functions that involve using new_event_loop based off winloop/uvloop's new_event_loop function and asyncio's as well. Something like this maybe to get around the different deprecated/removed approches.

@pytest.fixture(scope="session", autouse=True)
def new_event_loop() -> asyncio.AbstractEventLoop:
    """creates different asyncio event loops."""
    return asyncio.new_event_loop()

This fixure or apporch should be easy for anyone to pull off and here's an example of how I would go about using it.

import pytest
import sys
import asyncio

uvloop = pytest.importorskip("winloop" if sys.platform == "win32" else "uvloop", reason="uvloop library not installed")
UVLOOP_MARK = pytest.mark.uvloop_event_loop
ASYNCIO_MARK = pytest.mark.asyncio_event_loop

@pytest.fixture(
    scope="module",
    params=(
        asyncio.new_event_loop,
        pytest.param(
            uvloop.new_event_loop,
            marks=UVLOOP_MARK
        )
    )
)
def new_event_loop(request:pytest.FixtureRequest) -> asyncio.AbstractEventLoop:
    return request.param()

@pytest.mark.asyncio
async def do_test():
    ...
Vizonex commented 
from cyares.aio import DNSResolver
import asyncio
import pytest
import sys

# Only apply to aio and nowhere else...
uvloop = pytest.importorskip("winloop" if sys.platform == "win32" else "uvloop")


@pytest.fixture(
    scope="module", 
    params=(
        "uvloop/winloop",
        "std-asyncio"
    ), 
    # autouse allows us to override allowing multiple 
    # eventloops to be tested at a time.
    autouse=True,
    ids=str
)
def event_loop(request:pytest.FixtureRequest):
    if request.param == "uvloop/winloop":
        loop = uvloop.new_event_loop()
        yield loop 
    else:
        # XXX: DNS Resolver will freeze if we attempt to use 
        # ProactorEventLoop, your better off using winloop 
        # with the dns resolver. 
        if sys.platform == "win32":
            loop = asyncio.SelectorEventLoop()
            asyncio.set_event_loop(loop)
        else:
            loop = asyncio.new_event_loop()
        yield loop
    loop.close()


@pytest.mark.asyncio
async def test_dns_a():
    async with DNSResolver(["8.8.8.8", "8.8.4.4"]) as dns:
        t = await dns.query("google.com", "A")
    assert t

@pytest.mark.asyncio
async def test_dns_aaaa():
    async with DNSResolver(["8.8.8.8", "8.8.4.4"]) as dns:
        t = await dns.query("google.com", "AAAA")
    assert t

Nevermind I seem to have found one. It's not a pretty solution because I've isolated this to one module since the library I'm using this with only needs asyncio for one module, however I stand by my words of proposing updating the documentation to something that is not deprecated. Nope it's still broken.

Vizonex commented

I'm gonna try migrating to unittest.IsolatedAsyncioTestCase for the time being.