Update runserver for Asgi v3 (#1523)

* Convert StaticFilesWrapper to single callable.
* Make ProtocolTypeRouter instantiate default AsgiHandler.
* Adapt runserver command to ASGI v3.

channels/management/commands/runserver.py

@@ -2,6 +2,7 @@
 import logging
 import sys
 
+from daphne.cli import ASGI3Middleware
 from daphne.endpoints import build_endpoint_description_strings
 from daphne.server import Server
 from django.apps import apps
@@ -104,7 +105,7 @@ def inner_run(self, *args, **options):
         endpoints = build_endpoint_description_strings(host=self.addr, port=self.port)
         try:
             self.server_cls(
-                application=self.get_application(options),
+                application=ASGI3Middleware(self.get_application(options)),
                 endpoints=endpoints,
                 signal_handlers=not options["use_reloader"],
                 action_logger=self.log_action,

channels/routing.py

@@ -47,7 +47,7 @@ class ProtocolTypeRouter:
     def __init__(self, application_mapping):
         self.application_mapping = application_mapping
         if "http" not in self.application_mapping:
-            self.application_mapping["http"] = AsgiHandler
+            self.application_mapping["http"] = AsgiHandler()
 
     async def __call__(self, scope, receive, send):
         if scope["type"] in self.application_mapping:

channels/staticfiles.py

@@ -32,20 +32,24 @@ def _should_handle(self, path):
         """
         return path.startswith(self.base_url[2]) and not self.base_url[1]
 
-    def __call__(self, scope):
+    def __call__(self, scope, receive, send):
         # Only even look at HTTP requests
         if scope["type"] == "http" and self._should_handle(scope["path"]):
             # Serve static content
-            return StaticFilesHandler(dict(scope, static_base_url=self.base_url))
+            return StaticFilesHandler()(
+                dict(scope, static_base_url=self.base_url), receive, send
+            )
         # Hand off to the main app
-        return self.application(scope)
+        return self.application(scope, receive, send)
 
 
 class StaticFilesHandler(AsgiHandler):
     """
     Subclass of AsgiHandler that serves directly from its get_response.
     """
 
+    # TODO: Review hierarchy here. Do we NEED to inherit BaseHandler, AsgiHandler?
+
     def file_path(self, url):
         """
         Returns the relative path to the media file on disk for the given URL.

tests/test_routing.py

@@ -35,7 +35,7 @@ async def test_protocol_type_router():
     assert await router({"type": "http"}, None, None) == "http"
     # Test defaulting to AsgiHandler
     router = ProtocolTypeRouter({"websocket": MockApplication(return_value="ws")})
-    assert router.application_mapping["http"] == AsgiHandler
+    assert isinstance(router.application_mapping["http"], AsgiHandler)
     # Test an unmatched type
     with pytest.raises(ValueError):
         await router({"type": "aprs"}, None, None)