fix: fix the DeprecationWarning regarding no current event loop in test_bridge.py

tests/unit/langgraph/test_bridge.py

@@ -20,8 +20,21 @@ from rx.scheduler.eventloop import AsyncIOScheduler
 
 @pytest.fixture
 def scheduler():
-    """Fixture for AsyncIO scheduler."""
-    return AsyncIOScheduler(loop=asyncio.get_event_loop())
+    """Fixture for AsyncIO scheduler.
+
+    Note: This fixture works for both sync and async tests. It attempts to use
+    the running event loop (for async test contexts), or creates a new one if
+    needed (for sync test contexts). This avoids the Python 3.12+ deprecation
+    warning for asyncio.get_event_loop() when no loop exists.
+    """
+    try:
+        # Try to get the running loop (for async test contexts)
+        loop = asyncio.get_running_loop()
+    except RuntimeError:
+        # No running loop - create a new one for sync tests
+        loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(loop)
+    return AsyncIOScheduler(loop=loop)
 
 
 @pytest.fixture