Fix return on on_subscribe

Author: leandrodamascena

aws_lambda_powertools/event_handler/events_appsync/appsync_events.py

@@ -5,10 +5,10 @@
 import warnings
 from typing import TYPE_CHECKING, Any
 
+from aws_lambda_powertools.event_handler.events_appsync.exceptions import UnauthorizedException
 from aws_lambda_powertools.event_handler.events_appsync.router import Router
 from aws_lambda_powertools.utilities.data_classes.appsync_resolver_events_event import AppSyncResolverEventsEvent
 from aws_lambda_powertools.warnings import PowertoolsUserWarning
-from aws_lambda_powertools.event_handler.events_appsync.exceptions import UnauthorizedException
 
 if TYPE_CHECKING:
     from collections.abc import Callable
@@ -153,7 +153,8 @@ def _subscribe_events(self) -> Any:
         resolver = self._subscribe_registry.find_resolver(channel_path)
         if resolver:
             try:
-                return resolver["func"]()
+                resolver["func"]()
+                return None  # Must return None in subscribe events
             except UnauthorizedException:
                 raise
             except Exception as error:

tests/functional/event_handler/required_dependencies/appsync/test_appsync_events_resolvers.py

@@ -1535,6 +1535,7 @@ def test_handler():
     assert "error" in result
     assert "ValueError - Test error" in result["error"]
 
+
 def test_subscribe_event_with_valid_return(lambda_context, mock_event):
     """Test error handling during publish event processing."""
     # GIVEN a sample publish event
@@ -1551,8 +1552,9 @@ def test_handler():
     # WHEN we resolve the event
     result = app.resolve(mock_event, lambda_context)
 
-    # THEN we should get an error response
-    assert result == 1
+    # THEN we should return None because subscribe always must return None
+    assert result is None
+
 
 def test_subscribe_event_with_no_resolver(lambda_context, mock_event):
     """Test error handling during publish event processing."""
@@ -1573,6 +1575,7 @@ def test_handler():
     # THEN we should get an error response
     assert not result
 
+
 def test_publish_events_throw_unauthorized_exception(lambda_context, mock_event):
     """Test handling events with an empty payload."""
     # GIVEN a sample publish event with empty events
@@ -1593,6 +1596,7 @@ def handle_events(payload):
     with pytest.raises(UnauthorizedException):
         app.resolve(mock_event, lambda_context)
 
+
 def test_subscribe_events_throw_unauthorized_exception(lambda_context, mock_event):
     """Test handling events with an empty payload."""
     # GIVEN a sample publish event with empty events