Add automatically a SafeChildWatcher to the test loop (#2075)

The fact that on Unix system we don't create automatically a child
watcher makes all call to asyncio.create_subprocess_* to fail.

Author: cecton

aiohttp/test_utils.py

@@ -5,6 +5,7 @@
 import functools
 import gc
 import socket
+import sys
 import unittest
 from abc import ABC, abstractmethod
 from contextlib import contextmanager
@@ -446,6 +447,11 @@ def setup_test_loop(loop_factory=asyncio.new_event_loop):
     """
     loop = loop_factory()
     asyncio.set_event_loop(None)
+    if sys.platform != "win32":
+        policy = asyncio.get_event_loop_policy()
+        watcher = asyncio.SafeChildWatcher()
+        watcher.attach_loop(loop)
+        policy.set_child_watcher(watcher)
     return loop
 
 

changes/2058.feature

@@ -0,0 +1 @@
+Add automatically a SafeChildWatcher to the test loop

tests/test_loop.py

@@ -0,0 +1,16 @@
+import asyncio
+import platform
+import threading
+
+import pytest
+
+
+@pytest.mark.skipif(platform.system() == "Windows",
+                    reason="the test is not valid for Windows")
+@asyncio.coroutine
+def test_subprocess_co(loop):
+    assert isinstance(threading.current_thread(), threading._MainThread)
+    proc = yield from asyncio.create_subprocess_shell(
+        "exit 0", loop=loop, stdin=asyncio.subprocess.DEVNULL,
+        stdout=asyncio.subprocess.DEVNULL, stderr=asyncio.subprocess.DEVNULL)
+    yield from proc.wait()