ASGI tests are failing on Python 3.14 due to missing event loop

[mgorny]

All of the tests in tests/test_asgi.py are failing with Python 3.14.0rc2:

$ uv pip install -e . pytest asgiref
Resolved 7 packages in 2ms
      Built prometheus-client @ file:///tmp/client_python
Prepared 1 package in 648ms
Installed 7 packages in 9ms
 + asgiref==3.9.1
 + iniconfig==2.1.0
 + packaging==25.0
 + pluggy==1.6.0
 + prometheus-client==0.23.0 (from file:///tmp/client_python)
 + pygments==2.19.2
 + pytest==8.4.2
$ .venv/bin/pytest tests/test_asgi.py -x
========================================================= test session starts =========================================================
platform linux -- Python 3.14.0rc2, pytest-8.4.2, pluggy-1.6.0
rootdir: /tmp/client_python
configfile: pyproject.toml
collected 9 items                                                                                                                     

tests/test_asgi.py FE

=============================================================== ERRORS ================================================================
_______________________________________________ ERROR at teardown of ASGITest.test_gzip _______________________________________________

self = <tests.test_asgi.ASGITest testMethod=test_gzip>

    def tearDown(self):
        if self.communicator:
>           asyncio.get_event_loop().run_until_complete(
            ^^^^^^^^^^^^^^^^^^^^^^^^
                self.communicator.wait()
            )

tests/test_asgi.py:48: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <asyncio.unix_events._UnixDefaultEventLoopPolicy object at 0x7f893e9078c0>

    def get_event_loop(self):
        """Get the event loop for the current context.
    
        Returns an instance of EventLoop or raises an exception.
        """
        if self._local._loop is None:
>           raise RuntimeError('There is no current event loop in thread %r.'
                               % threading.current_thread().name)
E           RuntimeError: There is no current event loop in thread 'MainThread'.

/usr/lib/python3.14/asyncio/events.py:715: RuntimeError
============================================================== FAILURES ===============================================================
_________________________________________________________ ASGITest.test_gzip __________________________________________________________

self = <tests.test_asgi.ASGITest testMethod=test_gzip>

    def test_gzip(self):
        # Increment a metric.
        metric_name = "counter"
        help_text = "A counter"
        increments = 2
        self.increment_metrics(metric_name, help_text, increments)
        app = make_asgi_app(self.registry)
        self.seed_app(app)
        # Send input with gzip header.
        self.scope["headers"] = [(b"accept-encoding", b"gzip")]
>       self.send_input({"type": "http.request", "body": b""})

tests/test_asgi.py:163: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
tests/test_asgi.py:56: in send_input
    asyncio.get_event_loop().run_until_complete(
    ^^^^^^^^^^^^^^^^^^^^^^^^
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <asyncio.unix_events._UnixDefaultEventLoopPolicy object at 0x7f893e9078c0>

    def get_event_loop(self):
        """Get the event loop for the current context.
    
        Returns an instance of EventLoop or raises an exception.
        """
        if self._local._loop is None:
>           raise RuntimeError('There is no current event loop in thread %r.'
                               % threading.current_thread().name)
E           RuntimeError: There is no current event loop in thread 'MainThread'.

/usr/lib/python3.14/asyncio/events.py:715: RuntimeError
======================================================= short test summary info =======================================================
FAILED tests/test_asgi.py::ASGITest::test_gzip - RuntimeError: There is no current event loop in thread 'MainThread'.
ERROR tests/test_asgi.py::ASGITest::test_gzip - RuntimeError: There is no current event loop in thread 'MainThread'.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! stopping after 2 failures !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
===================================================== 1 failed, 1 error in 0.15s ======================================================

Note that using asyncio.get_event_loop() to create a new event loop was deprecated, and in Python 3.14 it raises an exception instead. FWIU you need to create the event loop yourself (I gues in the setUp() method).

I can reproduce this with 0.23.0.