streams: Backend changes to support anonymous groups.

can_remove_subscribers_group setting can now be set to
anonymous user groups.

Co-authored-by: Sahil Batra <sahil@zulip.com>

zerver/lib/event_schema.py

@@ -45,13 +45,26 @@ from zerver.lib.data_types import (
     make_checker,
 )
 from zerver.lib.topic import ORIG_TOPIC, TOPIC_LINKS, TOPIC_NAME
+from zerver.lib.types import AnonymousSettingGroupDict
 from zerver.models import Realm, RealmUserDefault, Stream, UserProfile
 
+group_setting_type = UnionType(
+    [
+        int,
+        DictType(
+            required_keys=[
+                ("direct_members", ListType(int)),
+                ("direct_subgroups", ListType(int)),
+            ]
+        ),
+    ]
+)
+
 # These fields are used for "stream" events, and are included in the
 # larger "subscription" events that also contain personal settings.
 default_stream_fields = [
     ("is_archived", bool),
-    ("can_remove_subscribers_group", int),
+    ("can_remove_subscribers_group", group_setting_type),
     ("creator_id", OptionalType(int)),
     ("date_created", int),
     ("description", str),
@@ -103,6 +116,12 @@ optional_value_type = UnionType(
         bool,
         int,
         str,
+        DictType(
+            required_keys=[
+                ("direct_members", ListType(int)),
+                ("direct_subgroups", ListType(int)),
+            ]
+        ),
         Equals(None),
     ]
 )
@@ -1046,18 +1065,6 @@ night_logo_data = DictType(
     ]
 )
 
-group_setting_type = UnionType(
-    [
-        int,
-        DictType(
-            required_keys=[
-                ("direct_members", ListType(int)),
-                ("direct_subgroups", ListType(int)),
-            ]
-        ),
-    ]
-)
-
 group_setting_update_data_type = DictType(
     required_keys=[],
     optional_keys=[
@@ -1442,7 +1449,7 @@ def check_stream_update(
         assert value in Stream.STREAM_POST_POLICY_TYPES
     elif prop == "can_remove_subscribers_group":
         assert extra_keys == set()
-        assert isinstance(value, int)
+        assert isinstance(value, int | AnonymousSettingGroupDict)
     elif prop == "first_message_id":
         assert extra_keys == set()
         assert isinstance(value, int)