From ed08fa364098327965bd32788dd08bc4c991a59f Mon Sep 17 00:00:00 2001
From: David Brochart <david.brochart@gmail.com>
Date: Tue, 19 Nov 2024 15:39:38 +0100
Subject: [PATCH] -

---
 ipykernel/kernelapp.py | 31 ------------------------------
 tests/conftest.py      |  6 ------
 tests/test_async.py    | 43 +++++++++++++++++++++++++++---------------
 3 files changed, 28 insertions(+), 52 deletions(-)

diff --git a/ipykernel/kernelapp.py b/ipykernel/kernelapp.py
index 407d8d58..1cf5697b 100644
--- a/ipykernel/kernelapp.py
+++ b/ipykernel/kernelapp.py
@@ -635,36 +635,6 @@ def configure_tornado_logger(self):
         handler.setFormatter(formatter)
         logger.addHandler(handler)
 
-    def _init_asyncio_patch(self):
-        """set default asyncio policy to be compatible with tornado
-        Tornado 6 (at least) is not compatible with the default
-        asyncio implementation on Windows
-        Pick the older SelectorEventLoopPolicy on Windows
-        if the known-incompatible default policy is in use.
-        Support for Proactor via a background thread is available in tornado 6.1,
-        but it is still preferable to run the Selector in the main thread
-        instead of the background.
-        do this as early as possible to make it a low priority and overridable
-        ref: https://github.com/tornadoweb/tornado/issues/2608
-        FIXME: if/when tornado supports the defaults in asyncio without threads,
-               remove and bump tornado requirement for py38.
-               Most likely, this will mean a new Python version
-               where asyncio.ProactorEventLoop supports add_reader and friends.
-        """
-        if sys.platform.startswith("win"):
-            import asyncio
-
-            try:
-                from asyncio import WindowsProactorEventLoopPolicy, WindowsSelectorEventLoopPolicy
-            except ImportError:
-                pass
-                # not affected
-            else:
-                if type(asyncio.get_event_loop_policy()) is WindowsProactorEventLoopPolicy:
-                    # WindowsProactorEventLoopPolicy is not compatible with tornado 6
-                    # fallback to the pre-3.8 default of Selector
-                    asyncio.set_event_loop_policy(WindowsSelectorEventLoopPolicy())
-
     def init_pdb(self):
         """Replace pdb with IPython's version that is interruptible.
 
@@ -684,7 +654,6 @@ def init_pdb(self):
     @catch_config_error
     def initialize(self, argv=None):
         """Initialize the application."""
-        self._init_asyncio_patch()
         super().initialize(argv)
         if self.subapp is not None:
             return
diff --git a/tests/conftest.py b/tests/conftest.py
index 49e38c7c..54a644da 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,4 +1,3 @@
-import asyncio
 import logging
 import os
 from math import inf
@@ -42,11 +41,6 @@
     resource.setrlimit(resource.RLIMIT_NOFILE, (soft, hard))
 
 
-# Enforce selector event loop on Windows.
-if os.name == "nt":
-    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())  # type:ignore
-
-
 class TestSession(Session):
     """A session that copies sent messages to an internal stream, so that
     they can be accessed later.
diff --git a/tests/test_async.py b/tests/test_async.py
index c2dd980b..ac935a52 100644
--- a/tests/test_async.py
+++ b/tests/test_async.py
@@ -4,6 +4,7 @@
 import time
 
 import pytest
+import zmq
 
 from .test_message_spec import validate_message
 from .utils import TIMEOUT, execute, flush_channels, start_new_kernel
@@ -11,23 +12,35 @@
 KC = KM = None
 
 
-@pytest.fixture(autouse=True)
-def _setup_env():
-    """start the global kernel (if it isn't running) and return its client"""
-    global KM, KC
-    KM, KC = start_new_kernel()
-    flush_channels(KC)
-    yield
-    assert KC is not None
-    assert KM is not None
-    KC.stop_channels()
-    KM.shutdown_kernel(now=True)
+async def test_context():
+    context = zmq.Context()
+    a, b = Socket(context, zmq.PAIR), Socket(context, zmq.PAIR)
+    port = a.bind_to_random_port("tcp://127.0.0.1")
+    b.connect(f'tcp://127.0.0.1:{port}')
+    a.send(b"Hello")
+    assert b.recv() == b"Hello"
+    async with a, b:
+        await a.asend(b"Hello")
+        assert await b.arecv() == b"Hello"
 
 
-def test_async_await():
-    flush_channels(KC)
-    msg_id, content = execute("import asyncio; await asyncio.sleep(0.1)", KC)
-    assert content["status"] == "ok", content
+# @pytest.fixture(autouse=True)
+# def _setup_env():
+#     """start the global kernel (if it isn't running) and return its client"""
+#     global KM, KC
+#     KM, KC = start_new_kernel()
+#     flush_channels(KC)
+#     yield
+#     assert KC is not None
+#     assert KM is not None
+#     KC.stop_channels()
+#     KM.shutdown_kernel(now=True)
+# 
+# 
+# def test_async_await():
+#     flush_channels(KC)
+#     msg_id, content = execute("import asyncio; await asyncio.sleep(0.1)", KC)
+#     assert content["status"] == "ok", content
 
 
 @pytest.mark.skipif(os.name == "nt", reason="Cannot interrupt on Windows")