Add server.start_serving and server.serve_forever to AsyncioServer proxy object, to match asyncio-python3.7 example doc, fixes #1754 (#1762)

sanic/server.py

@@ -735,6 +735,26 @@ class AsyncioServer:
             task = asyncio.ensure_future(coro, loop=self.loop)
             return task
 
+    def start_serving(self):
+        if self.server:
+            try:
+                return self.server.start_serving()
+            except AttributeError:
+                raise NotImplementedError(
+                    "server.start_serving not available in this version "
+                    "of asyncio or uvloop."
+                )
+
+    def serve_forever(self):
+        if self.server:
+            try:
+                return self.server.serve_forever()
+            except AttributeError:
+                raise NotImplementedError(
+                    "server.serve_forever not available in this version "
+                    "of asyncio or uvloop."
+                )
+
     def __await__(self):
         """Starts the asyncio server, returns AsyncServerCoro"""
         task = asyncio.ensure_future(self.serve_coro)

tests/test_app.py

@@ -44,7 +44,7 @@ def test_create_asyncio_server(app):
 @pytest.mark.skipif(
     sys.version_info < (3, 7), reason="requires python3.7 or higher"
 )
-def test_asyncio_server_start_serving(app):
+def test_asyncio_server_no_start_serving(app):
     if not uvloop_installed():
         loop = asyncio.get_event_loop()
         asyncio_srv_coro = app.create_server(
@@ -54,6 +54,22 @@ def test_asyncio_server_start_serving(app):
         srv = loop.run_until_complete(asyncio_srv_coro)
         assert srv.is_serving() is False
 
+@pytest.mark.skipif(
+    sys.version_info < (3, 7), reason="requires python3.7 or higher"
+)
+def test_asyncio_server_start_serving(app):
+    if not uvloop_installed():
+        loop = asyncio.get_event_loop()
+        asyncio_srv_coro = app.create_server(
+            return_asyncio_server=True,
+            asyncio_server_kwargs=dict(start_serving=False),
+        )
+        srv = loop.run_until_complete(asyncio_srv_coro)
+        assert srv.is_serving() is False
+        loop.run_until_complete(srv.start_serving())
+        assert srv.is_serving() is True
+        srv.close()
+        # Looks like we can't easily test `serve_forever()`
 
 def test_app_loop_not_running(app):
     with pytest.raises(SanicException) as excinfo: