add ensure_future method

tests/test_ensure_future.py

@@ -0,0 +1,30 @@
+import sanic
+from sanic.utils import sanic_endpoint_test
+from sanic.response import text
+from threading import Event
+import asyncio
+
+def test_ensure_future():
+    e = Event()
+    async def coro():
+        await asyncio.sleep(0.05)
+        e.set()
+
+    app = sanic.Sanic()
+    app.ensure_future(coro)
+
+    @app.route('/early')
+    def not_set(request):
+        return text(e.is_set())
+
+    @app.route('/late')
+    async def set(request):
+        await asyncio.sleep(0.1)
+        return text(e.is_set())
+
+
+    request, response = sanic_endpoint_test(app, uri='/early')
+    assert response.body == b'False'
+
+    request, response = sanic_endpoint_test(app, uri='/late')
+    assert response.body == b'True'