From 2c920e3518f506602950abd1fdbd49c4a9e09c0d Mon Sep 17 00:00:00 2001
From: maximlt <mliquet@anaconda.com>
Date: Mon, 3 Oct 2022 19:25:02 +0200
Subject: [PATCH 1/2] set the event loop policy on Windows

---
 nbsmoke/__init__.py | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/nbsmoke/__init__.py b/nbsmoke/__init__.py
index 83da5a4..e85aa2d 100644
--- a/nbsmoke/__init__.py
+++ b/nbsmoke/__init__.py
@@ -8,6 +8,7 @@
 import os
 import io
 import contextlib
+import sys
 
 import param
 
@@ -91,6 +92,20 @@ def cwd(d):
         os.chdir(orig)
 
 
+def fixup_windows_event_loop_policy() -> None:
+    if (
+        sys.platform == 'win32'
+        and sys.version_info[:3] >= (3, 8, 0)
+        and tornado.version_info < (6, 1)
+    ):
+        import asyncio
+        if type(asyncio.get_event_loop_policy()) is asyncio.WindowsProactorEventLoopPolicy:
+            # WindowsProactorEventLoopPolicy is not compatible with tornado 6
+            # fallback to the pre-3.8 default of WindowsSelectorEventLoopPolicy
+            asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
+
+
+fixup_windows_event_loop_policy()
 
 ###################################################
 

From 05410ef80a96127eeb43f0d294c50e282f22f446 Mon Sep 17 00:00:00 2001
From: maximlt <mliquet@anaconda.com>
Date: Mon, 3 Oct 2022 19:33:14 +0200
Subject: [PATCH 2/2] check for tornado

---
 nbsmoke/__init__.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/nbsmoke/__init__.py b/nbsmoke/__init__.py
index e85aa2d..d5313ab 100644
--- a/nbsmoke/__init__.py
+++ b/nbsmoke/__init__.py
@@ -93,6 +93,13 @@ def cwd(d):
 
 
 def fixup_windows_event_loop_policy() -> None:
+    try:
+        import tornado
+    except ImportError:
+        tornado = None
+    if not tornado:
+        return
+    # This part of the code comes from Bokeh's source code.
     if (
         sys.platform == 'win32'
         and sys.version_info[:3] >= (3, 8, 0)