Merge branch 'main' into deprecate-multi-loop-watcher

Lib/test/test_asyncio/test_subprocess.py

@@ -699,6 +699,31 @@ def test_deprecated(self):
             with self.assertWarns(DeprecationWarning):
                 asyncio.MultiLoopChildWatcher()
 
+    class GenericWatcherTests(test_utils.TestCase):
+
+        def test_create_subprocess_fails_with_inactive_watcher(self):
+            watcher = mock.create_autospec(
+                asyncio.AbstractChildWatcher,
+                **{"__enter__.return_value.is_active.return_value": False}
+            )
+
+            async def execute():
+                asyncio.set_child_watcher(watcher)
+
+                with self.assertRaises(RuntimeError):
+                    await subprocess.create_subprocess_exec(
+                        os_helper.FakePath(sys.executable), '-c', 'pass')
+
+                watcher.add_child_handler.assert_not_called()
+
+            with asyncio.Runner(loop_factory=asyncio.new_event_loop) as runner:
+                self.assertIsNone(runner.run(execute()))
+            self.assertListEqual(watcher.mock_calls, [
+                mock.call.__enter__(),
+                mock.call.__enter__().is_active(),
+                mock.call.__exit__(RuntimeError, mock.ANY, mock.ANY),
+            ])
+
 else:
     # Windows
     class SubprocessProactorTests(SubprocessMixin, test_utils.TestCase):