From feabc5dc44b3a5654b1222e70c9994bf1b93c2fa Mon Sep 17 00:00:00 2001
From: Yury Selivanov <yury@magic.io>
Date: Thu, 7 Jun 2018 12:38:21 -0400
Subject: [PATCH] bpo-33792: Add selector and proactor windows policies

---
 Doc/whatsnew/3.7.rst                          |  4 +++
 Lib/asyncio/windows_events.py                 | 11 +++++--
 Lib/test/test_asyncio/test_windows_events.py  | 31 +++++++++++++++++++
 .../2018-06-07-12-38-12.bpo-33792.3aKG7u.rst  |  2 ++
 4 files changed, 45 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2018-06-07-12-38-12.bpo-33792.3aKG7u.rst

diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst
index 3fe909ee978c24..9a6f542ec479ec 100644
--- a/Doc/whatsnew/3.7.rst
+++ b/Doc/whatsnew/3.7.rst
@@ -733,6 +733,10 @@ include:
 * Exceptions occurring in cancelled tasks are no longer logged.
   (Contributed by Yury Selivanov in :issue:`30508`.)
 
+* New ``WindowsSelectorEventLoopPolicy`` and
+  ``WindowsProactorEventLoopPolicy`` classes.
+  (Contributed by Yury Selivanov in :issue:`33792`.)
+
 Several ``asyncio`` APIs have been
 :ref:`deprecated <whatsnew37-asyncio-deprecated>`.
 
diff --git a/Lib/asyncio/windows_events.py b/Lib/asyncio/windows_events.py
index d22edec51efc1f..2ec542764375e9 100644
--- a/Lib/asyncio/windows_events.py
+++ b/Lib/asyncio/windows_events.py
@@ -21,7 +21,8 @@
 
 __all__ = (
     'SelectorEventLoop', 'ProactorEventLoop', 'IocpProactor',
-    'DefaultEventLoopPolicy',
+    'DefaultEventLoopPolicy', 'WindowsSelectorEventLoopPolicy',
+    'WindowsProactorEventLoopPolicy',
 )
 
 
@@ -801,8 +802,12 @@ def callback(f):
 SelectorEventLoop = _WindowsSelectorEventLoop
 
 
-class _WindowsDefaultEventLoopPolicy(events.BaseDefaultEventLoopPolicy):
+class WindowsSelectorEventLoopPolicy(events.BaseDefaultEventLoopPolicy):
     _loop_factory = SelectorEventLoop
 
 
-DefaultEventLoopPolicy = _WindowsDefaultEventLoopPolicy
+class WindowsProactorEventLoopPolicy(events.BaseDefaultEventLoopPolicy):
+    _loop_factory = ProactorEventLoop
+
+
+DefaultEventLoopPolicy = WindowsSelectorEventLoopPolicy
diff --git a/Lib/test/test_asyncio/test_windows_events.py b/Lib/test/test_asyncio/test_windows_events.py
index f92911ea3ba29c..8f4c50e2c92b45 100644
--- a/Lib/test/test_asyncio/test_windows_events.py
+++ b/Lib/test/test_asyncio/test_windows_events.py
@@ -166,5 +166,36 @@ def test_wait_for_handle_cancel(self):
         fut.cancel()
 
 
+class WinPolicyTests(test_utils.TestCase):
+
+    def test_selector_win_policy(self):
+        async def main():
+            self.assertIsInstance(
+                asyncio.get_running_loop(),
+                asyncio.SelectorEventLoop)
+
+        old_policy = asyncio.get_event_loop_policy()
+        try:
+            asyncio.set_event_loop_policy(
+                asyncio.WindowsSelectorEventLoopPolicy())
+            asyncio.run(main())
+        finally:
+            asyncio.set_event_loop_policy(old_policy)
+
+    def test_proactor_win_policy(self):
+        async def main():
+            self.assertIsInstance(
+                asyncio.get_running_loop(),
+                asyncio.ProactorEventLoop)
+
+        old_policy = asyncio.get_event_loop_policy()
+        try:
+            asyncio.set_event_loop_policy(
+                asyncio.WindowsProactorEventLoopPolicy())
+            asyncio.run(main())
+        finally:
+            asyncio.set_event_loop_policy(old_policy)
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2018-06-07-12-38-12.bpo-33792.3aKG7u.rst b/Misc/NEWS.d/next/Library/2018-06-07-12-38-12.bpo-33792.3aKG7u.rst
new file mode 100644
index 00000000000000..8c01764bc68233
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-06-07-12-38-12.bpo-33792.3aKG7u.rst
@@ -0,0 +1,2 @@
+Add asyncio.WindowsSelectorEventLoopPolicy and
+asyncio.WindowsProactorEventLoopPolicy.