fix: Python 3.14 get_event_loop_policy() deprecated warn

pyvista/pyvista#7938

Author: Chaoses-Ib

README.md

@@ -45,6 +45,8 @@ generally can't be patched.
 ## Comparison with `nest_asyncio`
 `nest-asyncio2` is a fork of the unmaintained [`nest_asyncio`](https://github.com/erdewit/nest_asyncio), with the following changes:
 - Python 3.12 `loop_factory` parameter support
-- Python 3.14 support (`asyncio.current_task()` and others are broken in `nest_asyncio`)
+- Python 3.14 support
+  - Fix broken `asyncio.current_task()` and others
+  - Fix `DeprecationWarning: 'asyncio.get_event_loop_policy' is deprecated and slated for removal in Python 3.16`
 
 All interfaces are kept as they are. To migrate, you just need to change the package and module name to `nest_asyncio2`.

nest_asyncio2.py

@@ -83,7 +83,8 @@ def _get_event_loop(stacklevel=3):
     if sys.version_info < (3, 7, 0):
         asyncio.tasks._current_tasks = asyncio.tasks.Task._current_tasks
         asyncio.all_tasks = asyncio.tasks.Task.all_tasks
-    if sys.version_info >= (3, 9, 0):
+    # The same as asyncio.get_event_loop() on at least Python 3.14
+    if sys.version_info >= (3, 9, 0) and sys.version_info < (3, 14, 0):
         events._get_event_loop = events.get_event_loop = \
             asyncio.get_event_loop = _get_event_loop
     asyncio.run = run
@@ -93,14 +94,22 @@ def _get_event_loop(stacklevel=3):
 def _patch_policy():
     """Patch the policy to always return a patched loop."""
 
+    # Removed in Python 3.16
+    # https://github.com/python/cpython/issues/127949
+    if sys.version_info >= (3, 16, 0):
+        return
+
     def get_event_loop(self):
         if self._local._loop is None:
             loop = self.new_event_loop()
             _patch_loop(loop)
             self.set_event_loop(loop)
         return self._local._loop
 
-    policy = events.get_event_loop_policy()
+    if sys.version_info < (3, 14, 0):
+        policy = events.get_event_loop_policy()
+    else:
+        policy = events._get_event_loop_policy()
     policy.__class__.get_event_loop = get_event_loop
 
 

setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = nest-asyncio2
-version = 1.6.1
+version = 1.6.2
 author = Ewald R. de Wit
 author_email = [email protected]
 license = BSD

tests/314_task.py

@@ -7,10 +7,15 @@
 # [tool.uv.sources]
 # nest-asyncio2 = { path = "../", editable = true }
 # ///
+import warnings
+warnings.filterwarnings("default")
+
 import asyncio
 import nest_asyncio2
 
-nest_asyncio2.apply()
+with warnings.catch_warnings(record=True) as w:
+    nest_asyncio2.apply()
+    assert len(w) == 0, w
 
 async def f():
     print(asyncio.get_running_loop())
@@ -28,4 +33,6 @@ async def f():
     print(asyncio.tasks._current_tasks)
     # assert asyncio.tasks._current_tasks == {}
 
-asyncio.run(f())
+with warnings.catch_warnings(record=True) as w:
+    asyncio.run(f())
+    assert len(w) == 0, w

tests/314_task_mix.py

@@ -7,6 +7,9 @@
 # [tool.uv.sources]
 # nest-asyncio2 = { path = "../", editable = true }
 # ///
+import warnings
+warnings.filterwarnings("default")
+
 import asyncio
 import nest_asyncio2