Option to disable routing in ASGIApp (Fixes #345)

src/engineio/async_drivers/asgi.py

@@ -19,7 +19,12 @@ class ASGIApp:
     :param other_asgi_app: A separate ASGI app that receives all other traffic.
     :param engineio_path: The endpoint where the Engine.IO application should
                           be installed. The default value is appropriate for
-                          most cases.
+                          most cases. With a value of ``None``, all incoming
+                          traffic is directed to the Engine.IO server, with the
+                          assumption that routing, if necessary, is handled by
+                          a different layer. When this option is set to
+                          ``None``, ``static_files`` and ``other_asgi_app`` are
+                          ignored.
     :param on_startup: function to be called on application startup; can be
                        coroutine
     :param on_shutdown: function to be called on application shutdown; can be
@@ -44,24 +49,26 @@ def __init__(self, engineio_server, other_asgi_app=None,
         self.engineio_server = engineio_server
         self.other_asgi_app = other_asgi_app
         self.engineio_path = engineio_path
-        if not self.engineio_path.startswith('/'):
-            self.engineio_path = '/' + self.engineio_path
-        if not self.engineio_path.endswith('/'):
-            self.engineio_path += '/'
+        if self.engineio_path is not None:
+            if not self.engineio_path.startswith('/'):
+                self.engineio_path = '/' + self.engineio_path
+            if not self.engineio_path.endswith('/'):
+                self.engineio_path += '/'
         self.static_files = static_files or {}
         self.on_startup = on_startup
         self.on_shutdown = on_shutdown
 
     async def __call__(self, scope, receive, send):
-        if scope['type'] in ['http', 'websocket'] and \
-                scope['path'].startswith(self.engineio_path):
+        if scope['type'] == 'lifespan':
+            await self.lifespan(scope, receive, send)
+        elif scope['type'] in ['http', 'websocket'] and (
+                self.engineio_path is None
+                or scope['path'].startswith(self.engineio_path)):
             await self.engineio_server.handle_request(scope, receive, send)
         else:
             static_file = get_static_file(scope['path'], self.static_files) \
                 if scope['type'] == 'http' and self.static_files else None
-            if scope['type'] == 'lifespan':
-                await self.lifespan(scope, receive, send)
-            elif static_file and os.path.exists(static_file['filename']):
+            if static_file and os.path.exists(static_file['filename']):
                 await self.serve_static_file(static_file, receive, send)
             elif self.other_asgi_app is not None:
                 await self.other_asgi_app(scope, receive, send)

tests/async/test_asgi.py

@@ -514,3 +514,30 @@ def test_make_response_websocket_reject_no_payload(self):
         environ['asgi.send'].mock.assert_called_with(
             {'type': 'websocket.close'}
         )
+
+    def test_sub_app_routing(self):
+
+        class ASGIDispatcher:
+            def __init__(self, routes):
+                self.routes = routes
+
+            async def __call__(self, scope, receive, send):
+                path = scope['path']
+                for prefix, app in self.routes.items():
+                    if path.startswith(prefix):
+                        await app(scope, receive, send)
+                        return
+                assert False, 'No route found'
+
+        other_app = AsyncMock()
+        mock_server = mock.MagicMock()
+        mock_server.handle_request = AsyncMock()
+        eio_app = async_asgi.ASGIApp(mock_server, engineio_path=None)
+        root_app = ASGIDispatcher({'/foo': other_app, '/eio': eio_app})
+        scope = {'type': 'http', 'path': '/foo/bar'}
+        _run(root_app(scope, 'receive', 'send'))
+        other_app.mock.assert_called_once_with(scope, 'receive', 'send')
+        scope = {'type': 'http', 'path': '/eio/'}
+        _run(root_app(scope, 'receive', 'send'))
+        eio_app.engineio_server.handle_request.mock.assert_called_once_with(
+            scope, 'receive', 'send')