Move MSC2432 stuff onto unstable prefix (#6948)

it's not in the spec yet, so needs to be unstable. Also add a feature flag for it. Also add a test for admin users.

changelog.d/6948.feature

@@ -0,0 +1 @@
+Implement `GET /_matrix/client/r0/rooms/{roomId}/aliases` endpoint as per [MSC2432](https://github.com/matrix-org/matrix-doc/pull/2432).

synapse/rest/client/v1/room.py

@@ -16,6 +16,7 @@
 
 """ This module contains REST servlets to do with rooms: /rooms/<paths> """
 import logging
+import re
 from typing import List, Optional
 
 from six.moves.urllib import parse as urlparse
@@ -848,7 +849,12 @@ async def on_PUT(self, request, room_id, user_id):
 
 
 class RoomAliasListServlet(RestServlet):
-    PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/aliases", unstable=False)
+    PATTERNS = [
+        re.compile(
+            r"^/_matrix/client/unstable/org\.matrix\.msc2432"
+            r"/rooms/(?P<room_id>[^/]*)/aliases"
+        ),
+    ]
 
     def __init__(self, hs: "synapse.server.HomeServer"):
         super().__init__()

synapse/rest/client/versions.py

@@ -72,6 +72,8 @@ def on_GET(self, request):
                     "org.matrix.label_based_filtering": True,
                     # Implements support for cross signing as described in MSC1756
                     "org.matrix.e2e_cross_signing": True,
+                    # Implements additional endpoints as described in MSC2432
+                    "org.matrix.msc2432": True,
                 },
             },
         )

tests/rest/client/v1/test_rooms.py

@@ -1729,8 +1729,7 @@ def test_erased_sender(self):
         self.assertEqual(events_after[1].get("content"), {}, events_after[1])
 
 
-class DirectoryTestCase(unittest.HomeserverTestCase):
-
+class RoomAliasListTestCase(unittest.HomeserverTestCase):
     servlets = [
         synapse.rest.admin.register_servlets_for_client_rest_resource,
         directory.register_servlets,
@@ -1756,6 +1755,16 @@ def test_not_in_room(self):
         res = self._get_aliases(user_tok, expected_code=403)
         self.assertEqual(res["errcode"], "M_FORBIDDEN")
 
+    def test_admin_user(self):
+        alias1 = self._random_alias()
+        self._set_alias_via_directory(alias1)
+
+        self.register_user("user", "test", admin=True)
+        user_tok = self.login("user", "test")
+
+        res = self._get_aliases(user_tok)
+        self.assertEqual(res["aliases"], [alias1])
+
     def test_with_aliases(self):
         alias1 = self._random_alias()
         alias2 = self._random_alias()
@@ -1770,7 +1779,8 @@ def _get_aliases(self, access_token: str, expected_code: int = 200) -> JsonDict:
         """Calls the endpoint under test. returns the json response object."""
         request, channel = self.make_request(
             "GET",
-            "/_matrix/client/r0/rooms/%s/aliases" % (self.room_id,),
+            "/_matrix/client/unstable/org.matrix.msc2432/rooms/%s/aliases"
+            % (self.room_id,),
             access_token=access_token,
         )
         self.render(request)