refactor: Extract send_peer_remove_event().

This prevents leaking some variables into an already
cluttered function.

We also add test coverage for what's now an
early-exit condition in the new function--we exempt
public MIT streams from these events.

zerver/lib/actions.py

@@ -2790,9 +2790,9 @@ def bulk_remove_subscriptions(users: Iterable[UserProfile],
 
     all_subscribers_by_stream = get_user_ids_for_streams(streams=streams)
 
-    for stream in streams:
+    def send_peer_remove_event(stream: Stream) -> None:
         if stream.is_in_zephyr_realm and not stream.invite_only:
-            continue
+            return
 
         altered_users = altered_user_dict[stream.id]
         altered_user_ids = [u.id for u in altered_users]
@@ -2813,6 +2813,9 @@ def bulk_remove_subscriptions(users: Iterable[UserProfile],
                              user_id=removed_user.id)
                 send_event(event, peer_user_ids)
 
+    for stream in streams:
+        send_peer_remove_event(stream=stream)
+
     new_vacant_streams = [stream for stream in
                           set(occupied_streams_before) - set(occupied_streams_after)]
     new_vacant_private_streams = [stream for stream in new_vacant_streams

zerver/tests/test_subs.py

@@ -2426,6 +2426,16 @@ class SubscriptionAPITest(ZulipTestCase):
         self.assert_length(events, 0)
         self.assert_length(queries, 9)
 
+        events = []
+        with tornado_redirected_to_list(events):
+            bulk_remove_subscriptions(
+                users=[mit_user],
+                streams=streams,
+                acting_client=get_client('website'),
+            )
+
+        self.assert_length(events, 0)
+
     def test_bulk_subscribe_many(self) -> None:
 
         # Create a whole bunch of streams