Fixed URLRouter root_path handling. (#1954)

* Add tests for handling root_path in URLRouting
* Handle root_path in URLRouter

If we have a scope["root_path"], raise if it does not prefix
scope["path"], and strip it from scope["path"] if it does. Do this
only if we're in an outermost URLRouter.

Signed-off-by: Alejandro R. Sedeño <asedeno@mit.edu>
Signed-off-by: Alejandro R Sedeño <asedeno@google.com>

channels/routing.py

@@ -107,6 +107,15 @@ async def __call__(self, scope, receive, send):
  path = scope.get("path_remaining", scope.get("path", None))
  if path is None:
  raise ValueError("No 'path' key in connection scope, cannot route URLs")
+
+ if "path_remaining" not in scope:
+ # We are the outermost URLRouter, so handle root_path if present.
+ root_path = scope.get("root_path", "")
+ if root_path and not path.startswith(root_path):
+ # If root_path is present, path must start with it.
+ raise ValueError("No route found for path %r." % path)
+ path = path[len(root_path) :]
+
  # Remove leading / to match Django's handling
  path = path.lstrip("/")
  # Run through the routes we have until one matches

tests/test_routing.py

@@ -107,6 +107,23 @@ async def test_url_router():
  "args": tuple(),
  "kwargs": {"default": 42},
  }
+ # Valid root_path in scope
+ assert (
+ await router(
+ {"type": "http", "path": "/root/", "root_path": "/root"}, None, None
+ )
+ == 1
+ )
+ assert (
+ await router(
+ {"type": "http", "path": "/root/foo/", "root_path": "/root"}, None, None
+ )
+ == 2
+ )
+
+ # Unmatched root_path in scope
+ with pytest.raises(ValueError):
+ await router({"type": "http", "path": "/", "root_path": "/root"}, None, None)
 
  # Invalid matches
  with pytest.raises(ValueError):
@@ -261,6 +278,29 @@ async def test_path_remaining():
  == 2
  )
 
+ assert (
+ await outermost_router(
+ {"type": "http", "path": "/root/prefix/stuff/", "root_path": "/root"},
+ None,
+ None,
+ )
+ == 2
+ )
+
+ with pytest.raises(ValueError):
+ await outermost_router(
+ {"type": "http", "path": "/root/root/prefix/stuff/", "root_path": "/root"},
+ None,
+ None,
+ )
+
+ with pytest.raises(ValueError):
+ await outermost_router(
+ {"type": "http", "path": "/root/prefix/root/stuff/", "root_path": "/root"},
+ None,
+ None,
+ )
+
 
 def test_invalid_routes():
  """