fix async run, add tests

sanic/server.py

@@ -297,7 +297,8 @@ def serve(host, port, request_handler, error_handler, before_start=None,
     :param protocol: Subclass of asyncio protocol class
     :return: Nothing
     """
-    loop = async_loop.new_event_loop()
+    loop = loop or async_loop.new_event_loop()
+    asyncio.set_event_loop_policy(async_loop.EventLoopPolicy())
     asyncio.set_event_loop(loop)
 
     if debug:

tests/test_async_run.py

@@ -0,0 +1,25 @@
+from sanic import Sanic
+from sanic.response import json
+import asyncio
+import requests
+from threading import Thread
+import pytest
+import sys
+
+@pytest.mark.skipif(sys.version_info < (3, 6),
+                    reason="fails on python 3.5 with travis")
+def test_async_run():
+    app = Sanic(__name__)
+
+    @app.route("/")
+    async def test(request):
+        return json({"answer": "42"})
+
+    server = app.create_server(host="0.0.0.0", port=8001)
+    task = asyncio.ensure_future(server)
+    loop = asyncio.get_event_loop()
+    t = Thread(target=loop.run_forever)
+    t.start()
+    res = requests.get('http://localhost:8001')
+    loop.stop()
+    assert res.json()['answer'] == '42'

tests/test_loop_policy.py

@@ -0,0 +1,18 @@
+from sanic import Sanic
+from sanic.response import text
+from sanic.utils import sanic_endpoint_test
+import asyncio
+import uvloop
+
+def test_loop_policy():
+    app = Sanic('test_loop_policy')
+
+    @app.route('/')
+    def test(request):
+        return text("OK")
+
+    server = app.create_server()
+
+    request, response = sanic_endpoint_test(app)
+    assert isinstance(asyncio.get_event_loop_policy(),
+                      uvloop.EventLoopPolicy)

tox.ini

@@ -14,6 +14,7 @@ deps =
     aiohttp
     pytest
     beautifulsoup4
+    requests
 
 commands =
     pytest tests {posargs}