GH-94597: Deprecate child watcher getters and setters (#98215)

This is the next step for deprecating child watchers.

Until we've removed the API completely we have to use it, so this PR is mostly suppressing a lot of warnings when using the API internally.

Once the child watcher API is totally removed, the two child watcher implementations we actually use and need (Pidfd and Thread) will be turned into internal helpers.

1 files changed, 20 insertions, 9 deletions

diff --git a/Lib/test/test_asyncio/test_subprocess.py b/Lib/test/test_asyncio/test_subprocess.py
index 64df1b17189..8e551155906 100644
--- a/Lib/test/test_asyncio/test_subprocess.py
+++ b/Lib/test/test_asyncio/test_subprocess.py
@@ -582,7 +582,9 @@ class SubprocessMixin:
         # manually to avoid a warning when the watcher is detached.
         if (sys.platform != 'win32' and
                 isinstance(self, SubprocessFastWatcherTests)):
-            asyncio.get_child_watcher()._callbacks.clear()
+            with warnings.catch_warnings():
+                warnings.simplefilter('ignore', DeprecationWarning)
+                asyncio.get_child_watcher()._callbacks.clear()
 
     async def _test_popen_error(self, stdin):
         if sys.platform == 'win32':
@@ -696,13 +698,17 @@ if sys.platform != 'win32':
 
             watcher = self._get_watcher()
             watcher.attach_loop(self.loop)
-            policy.set_child_watcher(watcher)
+            with warnings.catch_warnings():
+                warnings.simplefilter('ignore', DeprecationWarning)
+                policy.set_child_watcher(watcher)
 
         def tearDown(self):
             super().tearDown()
             policy = asyncio.get_event_loop_policy()
-            watcher = policy.get_child_watcher()
-            policy.set_child_watcher(None)
+            with warnings.catch_warnings():
+                warnings.simplefilter('ignore', DeprecationWarning)
+                watcher = policy.get_child_watcher()
+                policy.set_child_watcher(None)
             watcher.attach_loop(None)
             watcher.close()
 
@@ -752,7 +758,9 @@ if sys.platform != 'win32':
             )
 
             async def execute():
-                asyncio.set_child_watcher(watcher)
+                with warnings.catch_warnings():
+                    warnings.simplefilter('ignore', DeprecationWarning)
+                    asyncio.set_child_watcher(watcher)
 
                 with self.assertRaises(RuntimeError):
                     await subprocess.create_subprocess_exec(
@@ -761,7 +769,9 @@ if sys.platform != 'win32':
                 watcher.add_child_handler.assert_not_called()
 
             with asyncio.Runner(loop_factory=asyncio.new_event_loop) as runner:
-                self.assertIsNone(runner.run(execute()))
+                with warnings.catch_warnings():
+                    warnings.simplefilter('ignore', DeprecationWarning)
+                    self.assertIsNone(runner.run(execute()))
             self.assertListEqual(watcher.mock_calls, [
                 mock.call.__enter__(),
                 mock.call.__enter__().is_active(),
@@ -788,15 +798,16 @@ if sys.platform != 'win32':
                 with self.assertRaises(RuntimeError):
                     asyncio.get_event_loop_policy().get_event_loop()
                 return await asyncio.to_thread(asyncio.run, in_thread())
-
-            asyncio.set_child_watcher(asyncio.PidfdChildWatcher())
+            with self.assertWarns(DeprecationWarning):
+                asyncio.set_child_watcher(asyncio.PidfdChildWatcher())
             try:
                 with asyncio.Runner(loop_factory=asyncio.new_event_loop) as runner:
                     returncode, stdout = runner.run(main())
                 self.assertEqual(returncode, 0)
                 self.assertEqual(stdout, b'some data')
             finally:
-                asyncio.set_child_watcher(None)
+                with self.assertWarns(DeprecationWarning):
+                    asyncio.set_child_watcher(None)
 else:
     # Windows
     class SubprocessProactorTests(SubprocessMixin, test_utils.TestCase):