fix: await message confirmation interruption

backend/tests/test_pipeline_events.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 
 import unittest
 from types import SimpleNamespace
-from unittest.mock import patch
+from unittest.mock import AsyncMock, patch
 
 from pipecat.frames.frames import (
     BotStartedSpeakingFrame,
@@ -10,6 +10,7 @@ from pipecat.frames.frames import (
     OutputTransportMessageUrgentFrame,
 )
 from services.pipecat.pipeline_events import bind_cascade_pipeline_events
+from services.pipecat.pipeline import _interrupt_pipeline_output
 
 
 class _EventSource:
@@ -80,6 +81,25 @@ class _Brain:
 
 
 class PipelineEventTest(unittest.IsolatedAsyncioTestCase):
+    async def test_output_interruption_broadcasts_before_flush_barrier(self):
+        events = []
+        source = SimpleNamespace(
+            broadcast_interruption=AsyncMock(
+                side_effect=lambda: events.append("broadcast")
+            )
+        )
+        worker = SimpleNamespace(
+            flush_pipeline=AsyncMock(
+                side_effect=lambda **_kwargs: events.append("flush")
+            )
+        )
+
+        await _interrupt_pipeline_output(source, worker)
+
+        self.assertEqual(events, ["broadcast", "flush"])
+        source.broadcast_interruption.assert_awaited_once_with()
+        worker.flush_pipeline.assert_awaited_once_with(timeout=1.0)
+
     async def test_greeting_keeps_playback_timestamp_until_client_ready(self):
         transport = _EventSource()
         text_input = _EventSource()