Remove unused `room_alias` field from `/createRoom` response (#15093)

* Change `create_room` return type

* Don't return room alias from /createRoom

* Update other callsites

* Fix up mypy complaints

It looks like new_room_user_id is None iff new_room_id is None. It's a
shame we haven't expressed this in a way that mypy can understand.

* Changelog

4 files changed, 12 insertions, 11 deletions

diff --git a/tests/storage/test_cleanup_extrems.py b/tests/storage/test_cleanup_extrems.py
index d570684c99..7de109966d 100644
--- a/tests/storage/test_cleanup_extrems.py
+++ b/tests/storage/test_cleanup_extrems.py
@@ -43,8 +43,9 @@ class CleanupExtremBackgroundUpdateStoreTestCase(HomeserverTestCase):
         # Create a test user and room
         self.user = UserID("alice", "test")
         self.requester = create_requester(self.user)
-        info, _ = self.get_success(self.room_creator.create_room(self.requester, {}))
-        self.room_id = info["room_id"]
+        self.room_id, _, _ = self.get_success(
+            self.room_creator.create_room(self.requester, {})
+        )
 
     def run_background_update(self) -> None:
         """Re run the background update to clean up the extremities."""
@@ -275,10 +276,9 @@ class CleanupExtremDummyEventsTestCase(HomeserverTestCase):
         self.user = UserID.from_string(self.register_user("user1", "password"))
         self.token1 = self.login("user1", "password")
         self.requester = create_requester(self.user)
-        info, _ = self.get_success(
+        self.room_id, _, _ = self.get_success(
             self.room_creator.create_room(self.requester, {"visibility": "public"})
         )
-        self.room_id = info["room_id"]
         self.event_creator = homeserver.get_event_creation_handler()
         homeserver.config.consent.user_consent_version = self.CONSENT_VERSION
 
diff --git a/tests/storage/test_event_metrics.py b/tests/storage/test_event_metrics.py
index a91411168c..6897addbd3 100644
--- a/tests/storage/test_event_metrics.py
+++ b/tests/storage/test_event_metrics.py
@@ -33,8 +33,7 @@ class ExtremStatisticsTestCase(HomeserverTestCase):
         events = [(3, 2), (6, 2), (4, 6)]
 
         for event_count, extrems in events:
-            info, _ = self.get_success(room_creator.create_room(requester, {}))
-            room_id = info["room_id"]
+            room_id, _, _ = self.get_success(room_creator.create_room(requester, {}))
 
             last_event = None
 
diff --git a/tests/storage/test_receipts.py b/tests/storage/test_receipts.py
index 12c17f1073..1b52eef23f 100644
--- a/tests/storage/test_receipts.py
+++ b/tests/storage/test_receipts.py
@@ -50,12 +50,14 @@ class ReceiptTestCase(HomeserverTestCase):
         self.otherRequester = create_requester(self.otherUser)
 
         # Create a test room
-        info, _ = self.get_success(self.room_creator.create_room(self.ourRequester, {}))
-        self.room_id1 = info["room_id"]
+        self.room_id1, _, _ = self.get_success(
+            self.room_creator.create_room(self.ourRequester, {})
+        )
 
         # Create a second test room
-        info, _ = self.get_success(self.room_creator.create_room(self.ourRequester, {}))
-        self.room_id2 = info["room_id"]
+        self.room_id2, _, _ = self.get_success(
+            self.room_creator.create_room(self.ourRequester, {})
+        )
 
         # Join the second user to the first room
         memberEvent, memberEventContext = self.get_success(
diff --git a/tests/test_federation.py b/tests/test_federation.py
index 82dfd88b99..46d2f99eac 100644
--- a/tests/test_federation.py
+++ b/tests/test_federation.py
@@ -47,7 +47,7 @@ class MessageAcceptTests(unittest.HomeserverTestCase):
             room_creator.create_room(
                 our_user, room_creator._presets_dict["public_chat"], ratelimit=False
             )
-        )[0]["room_id"]
+        )[0]
 
         self.store = self.hs.get_datastores().main