test(alerting): close the coroutine the create_task mock intercepts

update_values builds periodic_flush() before handing it to the patched
asyncio.create_task, which neither schedules nor closes it, so garbage
collection emits an unawaited-coroutine warning. That is noise normally and
an error under -W error.

Applies to the pre-existing start test as well: it patches create_task the
same way, so fixing only the new one would leave the warning in place.

tests/test_litellm/integrations/SlackAlerting/test_slack_alerting.py

@@ -15,6 +15,16 @@ from litellm.proxy._types import CallInfo, Litellm_EntityType
 from litellm.types.integrations.slack_alerting import SlackAlertingCacheKeys
 
 
+def _close_and_stub(coro):
+    """asyncio.create_task stand-in: close the coroutine nothing will await.
+
+    Leaving it open emits an unawaited-coroutine warning, which is an error
+    under -W error.
+    """
+    coro.close()
+    return MagicMock()
+
+
 class TestSlackAlerting(unittest.TestCase):
     def setUp(self):
         self.slack_alerting = SlackAlerting()
@@ -156,8 +166,7 @@ class TestSlackAlerting(unittest.TestCase):
     # Calling update_values with alerting args should try to start the periodic task
     @patch("asyncio.create_task")
     def test_update_values_starts_periodic_task(self, mock_create_task):
-        # Make it do nothing (or return a dummy future)
-        mock_create_task.return_value = AsyncMock()  # prevents awaiting errors
+        mock_create_task.side_effect = _close_and_stub
 
         assert self.slack_alerting.periodic_started == False
 
@@ -169,7 +178,7 @@ class TestSlackAlerting(unittest.TestCase):
     # never exits, so they accumulate for the lifetime of the process).
     @patch("asyncio.create_task")
     def test_update_values_starts_periodic_task_only_once(self, mock_create_task):
-        mock_create_task.return_value = AsyncMock()
+        mock_create_task.side_effect = _close_and_stub
 
         for _ in range(5):
             self.slack_alerting.update_values(alerting=["slack"])