user_groups: Send metadata access related events on add subgroups.

zerver/actions/user_groups.py

@@ -448,6 +448,16 @@ def add_subgroups_to_user_group(
     *,
     acting_user: UserProfile | None,
 ) -> None:
+    if len(subgroups) == 0:
+        return
+
+    realm = user_group.realm
+    supergroups = get_recursive_supergroups_union_for_groups([user_group.id])
+    streams = list(
+        get_metadata_access_streams_via_group_ids([group.id for group in supergroups], realm)
+    )
+    old_stream_metadata_user_ids = bulk_can_access_stream_metadata_user_ids(streams)
+
     group_memberships = [
         GroupGroupMembership(supergroup=user_group, subgroup=subgroup) for subgroup in subgroups
     ]
@@ -478,8 +488,36 @@ def add_subgroups_to_user_group(
     ]
     RealmAuditLog.objects.bulk_create(audit_log_entries)
 
+    subscriber_ids_for_streams = get_user_ids_for_streams({stream.id for stream in streams})
+    new_stream_metadata_user_ids = bulk_can_access_stream_metadata_user_ids(streams)
+    recent_traffic = get_streams_traffic({stream.id for stream in streams}, realm)
+    anonymous_group_membership = get_anonymous_group_membership_dict_for_streams(streams)
+
     do_send_subgroups_update_event("add_subgroups", user_group, subgroup_ids)
 
+    for stream in streams:
+        user_ids_gaining_metadata_access = (
+            new_stream_metadata_user_ids[stream.id] - old_stream_metadata_user_ids[stream.id]
+        )
+        send_stream_creation_event(
+            realm,
+            stream,
+            list(user_ids_gaining_metadata_access),
+            recent_traffic,
+            anonymous_group_membership,
+        )
+        peer_add_event = dict(
+            type="subscription",
+            op="peer_add",
+            stream_ids=[stream.id],
+            user_ids=sorted(subscriber_ids_for_streams[stream.id]),
+        )
+        send_event_on_commit(
+            realm,
+            peer_add_event,
+            user_ids_gaining_metadata_access,
+        )
+
 
 @transaction.atomic(savepoint=False)
 def remove_subgroups_from_user_group(

zerver/tests/test_events.py

@@ -2232,7 +2232,11 @@ class NormalActionsTest(BaseAction):
         check_user_group_update("events[0]", events[0], {"name"})
 
     def do_test_user_group_events_on_stream_metadata_access_change(
-        self, setting_name: str, stream: Stream, user_group: NamedUserGroup
+        self,
+        setting_name: str,
+        stream: Stream,
+        user_group: NamedUserGroup,
+        hamlet_group: NamedUserGroup,
     ) -> None:
         othello = self.example_user("othello")
         hamlet = self.example_user("hamlet")
@@ -2249,6 +2253,15 @@ class NormalActionsTest(BaseAction):
                 bulk_remove_members_from_user_groups([user_group], [hamlet.id], acting_user=None)
             check_user_group_remove_members("events[0]", events[0])
             check_stream_delete("events[1]", events[1])
+
+            with self.verify_action(num_events=3) as events:
+                add_subgroups_to_user_group(user_group, [hamlet_group], acting_user=None)
+            check_user_group_add_subgroups("events[0]", events[0])
+            check_stream_create("events[1]", events[1])
+            check_subscription_peer_add("events[2]", events[2])
+
+            # Remove subgroup for next test.
+            remove_subgroups_from_user_group(user_group, [hamlet_group], acting_user=None)
         else:
             with self.verify_action() as events:
                 bulk_add_members_to_user_groups([user_group], [hamlet.id], acting_user=None)
@@ -2258,6 +2271,13 @@ class NormalActionsTest(BaseAction):
                 bulk_remove_members_from_user_groups([user_group], [hamlet.id], acting_user=None)
             check_user_group_remove_members("events[0]", events[0])
 
+            with self.verify_action() as events:
+                add_subgroups_to_user_group(user_group, [hamlet_group], acting_user=None)
+            check_user_group_add_subgroups("events[0]", events[0])
+
+            # Remove subgroup for next test.
+            remove_subgroups_from_user_group(user_group, [hamlet_group], acting_user=None)
+
         nobody_group = NamedUserGroup.objects.get(
             name=SystemGroups.NOBODY, realm=othello.realm, is_system_group=True
         )
@@ -2273,10 +2293,17 @@ class NormalActionsTest(BaseAction):
             "Test group",
             acting_user=self.example_user("othello"),
         )
+        hamlet_group = check_add_user_group(
+            self.user_profile.realm,
+            "hamlet_group",
+            [self.example_user("hamlet")],
+            "Hamlet group",
+            acting_user=self.example_user("othello"),
+        )
         private_stream = self.make_stream("private_stream", invite_only=True)
         for setting_name in Stream.stream_permission_group_settings:
             self.do_test_user_group_events_on_stream_metadata_access_change(
-                setting_name, private_stream, test_group
+                setting_name, private_stream, test_group, hamlet_group
             )
 
     def test_default_stream_groups_events(self) -> None:

zerver/tests/test_user_groups.py

@@ -571,6 +571,7 @@ class UserGroupTestCase(ZulipTestCase):
             bulk_add_members_to_user_groups([test_group], [], acting_user=None)
             bulk_remove_members_from_user_groups([], [hamlet.id], acting_user=None)
             bulk_remove_members_from_user_groups([test_group], [], acting_user=None)
+            add_subgroups_to_user_group(test_group, [], acting_user=None)
 
 
 class UserGroupAPITestCase(UserGroupTestCase):