Add python 3.12 support (#367)

Author: blink1073

.github/workflows/test.yml

@@ -28,12 +28,14 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        python-version: ["3.8", "3.11"]
+        python-version: ["3.8", "3.12"]
         include:
           - os: windows-latest
             python-version: "3.9"
           - os: ubuntu-latest
-            python-version: "pypy-3.8"
+            python-version: "3.11"
+          - os: ubuntu-latest
+            python-version: "pypy-3.9"
           - os: macos-latest
             python-version: "3.10"
     steps:

jupyter_core/utils/__init__.py

@@ -160,12 +160,17 @@ def wrapped(*args: Any, **kwargs: Any) -> Any:
             pass
 
         # Run the loop for this thread.
-        try:
-            loop = asyncio.get_event_loop()
-        except RuntimeError:
-            loop = asyncio.new_event_loop()
-            asyncio.set_event_loop(loop)
-        return loop.run_until_complete(inner)
+        # In Python 3.12, a deprecation warning is raised, which
+        # may later turn into a RuntimeError.  We handle both
+        # cases.
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            try:
+                loop = asyncio.get_event_loop()
+            except RuntimeError:
+                loop = asyncio.new_event_loop()
+                asyncio.set_event_loop(loop)
+            return loop.run_until_complete(inner)
 
     wrapped.__doc__ = coro.__doc__
     return wrapped

tests/test_async.py

@@ -0,0 +1,56 @@
+"""Tests for utils"""
+
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+import asyncio
+import os
+import tempfile
+
+import pytest
+
+from jupyter_core.utils import deprecation, ensure_async, ensure_dir_exists, run_sync
+
+
+def test_ensure_dir_exists():
+    with tempfile.TemporaryDirectory() as td:
+        ensure_dir_exists(td)
+        ensure_dir_exists(os.path.join(str(td), "foo"), 0o777)
+
+
+def test_deprecation():
+    with pytest.deprecated_call():
+        deprecation("foo")
+
+
+async def afunc():
+    return "afunc"
+
+
+def func():
+    return "func"
+
+
+sync_afunc = run_sync(afunc)
+
+
+def test_run_sync():
+    async def foo():
+        return 1
+
+    foo_sync = run_sync(foo)
+    assert foo_sync() == 1
+    assert foo_sync() == 1
+
+    asyncio.set_event_loop(None)
+    assert foo_sync() == 1
+
+    asyncio.run(foo())
+
+
+def test_ensure_async():
+    async def main():
+        assert await ensure_async(afunc()) == "afunc"
+        assert await ensure_async(func()) == "func"
+
+    asyncio.run(main())