streams: Extract zephyr realm invite check.

This will be reused later in the
`/channels/create` view.

Signed-off-by: apoorvapendse <apoorvavpendse@gmail.com>

zerver/lib/streams.py

@@ -997,6 +997,15 @@ def check_stream_name_available(realm: Realm, name: str) -> None:
         pass
 
 
+def check_zephyr_realm_invite_conditions(
+    is_subscribing_other_users: bool, realm: Realm, invite_only: bool
+) -> None:
+    if is_subscribing_other_users and realm.is_zephyr_mirror_realm and not invite_only:
+        raise JsonableError(
+            _("You can only invite other Zephyr mirroring users to private channels.")
+        )
+
+
 def access_stream_by_name(
     user_profile: UserProfile,
     stream_name: str,

zerver/views/streams.py

@@ -75,6 +75,7 @@ from zerver.lib.streams import (
     access_web_public_stream,
     channel_events_topic_name,
     check_stream_name_available,
+    check_zephyr_realm_invite_conditions,
     do_get_streams,
     filter_stream_authorization_for_adding_subscribers,
     get_anonymous_group_membership_dict_for_streams,
@@ -844,14 +845,8 @@ def add_subscriptions_backend(
     # Newly created streams are also authorized for the creator
     streams = authorized_streams + created_streams
 
-    if (
-        is_subscribing_other_users
-        and realm.is_zephyr_mirror_realm
-        and not all(stream.invite_only for stream in streams)
-    ):
-        raise JsonableError(
-            _("You can only invite other Zephyr mirroring users to private channels.")
-        )
+    for stream in streams:
+        check_zephyr_realm_invite_conditions(is_subscribing_other_users, realm, stream.invite_only)
 
     if is_subscribing_other_users:
         subscribers = bulk_principals_to_user_profiles(principals, user_profile)