Fix header name, add test

README.rst

@@ -30,11 +30,11 @@ Root Path (SCRIPT_NAME)
 In order to set the root path for Daphne, which is the equivalent of the
 WSGI ``SCRIPT_NAME`` setting, you have two options:
 
-* Pass a header value ``DAPHNE_ROOT_PATH``, with the desired root path as a
-  URLencoded ASCII value
+* Pass a header value ``Daphne-Root-Path``, with the desired root path as a
+  URLencoded ASCII value. This header will not be passed down to applications.
 
 * Set the ``--root-path`` commandline option with the desired root path as a
-  URLencoded ASCII value
+  URLencoded ASCII value.
 
 The header takes precedence if both are set. As with ``SCRIPT_ALIAS``, the value
 should start with a slash, but not end with one; for example::

daphne/http_protocol.py

@@ -117,7 +117,7 @@ class WebRequest(http.Request):
                     if b"_" in name:
                         continue
                     for value in values:
-                        if name.lower() == "daphne_root_path":
+                        if name.lower() == "daphne-root-path":
                             self.root_path = self.unquote(value)
                         else:
                             self.clean_headers.append((name.lower(), value))

daphne/tests/test_http.py

@@ -51,3 +51,18 @@ class TestHTTPProtocol(TestCase):
         )
         # Make sure that comes back right on the protocol
         self.assertEqual(self.tr.value(), b"HTTP/1.1 201 Created\r\nTransfer-Encoding: chunked\r\nX-Test: Boom!\r\n\r\n6\r\nOH HAI\r\n0\r\n\r\n")
+
+    def test_root_path_header(self):
+        """
+        Tests root path header handling
+        """
+        # Send a simple request to the protocol
+        self.proto.dataReceived(
+            b"GET /te%20st-%C3%A0/?foo=bar HTTP/1.1\r\n" +
+            b"Host: somewhere.com\r\n" +
+            b"Daphne-Root-Path: /foobar%20/bar\r\n" +
+            b"\r\n"
+        )
+        # Get the resulting message off of the channel layer, check root_path
+        _, message = self.channel_layer.receive_many(["http.request"])
+        self.assertEqual(message['root_path'], "/foobar /bar")