Fix History Event None Return (#466)

* check activity return not none

* avoid long line

* add check for subo and event

* fix indent

* update by review

* add unit test for call activity with none return

* update test

Author: nytian

azure/durable_functions/models/TaskOrchestrationExecutor.py

@@ -165,11 +165,14 @@ def parse_history_event(directive_result):
 
             # We provide the ability to deserialize custom objects, because the output of this
             # will be passed directly to the orchestrator as the output of some activity
-            if event_type == HistoryEventType.SUB_ORCHESTRATION_INSTANCE_COMPLETED:
+            if (event_type == HistoryEventType.SUB_ORCHESTRATION_INSTANCE_COMPLETED
+                    and directive_result.Result is not None):
                 return json.loads(directive_result.Result, object_hook=_deserialize_custom_object)
-            if event_type == HistoryEventType.TASK_COMPLETED:
+            if (event_type == HistoryEventType.TASK_COMPLETED
+                    and directive_result.Result is not None):
                 return json.loads(directive_result.Result, object_hook=_deserialize_custom_object)
-            if event_type == HistoryEventType.EVENT_RAISED:
+            if (event_type == HistoryEventType.EVENT_RAISED
+                    and directive_result.Input is not None):
                 # TODO: Investigate why the payload is in "Input" instead of "Result"
                 response = json.loads(directive_result.Input,
                                       object_hook=_deserialize_custom_object)

tests/orchestrator/test_sequential_orchestrator.py

@@ -257,10 +257,31 @@ def generator_function_call_activity_with_orchestrator(context):
 
     return outputs
 
+def generator_function_call_activity_with_none_return(context):
+    """Simple orchestrator that call activity function which can return None"""
+    outputs = []
+
+    task1 = yield context.call_activity(hello_return_none, "Tokyo")
+    task2 = yield context.call_activity(hello_return_none, "Seattle")
+    task3 = yield context.call_activity(hello_return_none, "London")
+
+    outputs.append(task1)
+    outputs.append(task2)
+    outputs.append(task3)
+
+    return outputs
+
 @app.activity_trigger(input_name = "myArg")
 def Hello(myArg: str):
     return "Hello" + myArg
 
+@app.activity_trigger(input_name = "myArg")
+def hello_return_none(myArg: str):
+    if myArg == "London":
+        return None
+    else:
+        return "Hello" + myArg
+
 def base_expected_state(output=None, replay_schema: ReplaySchema = ReplaySchema.V1) -> OrchestratorState:
     return OrchestratorState(is_done=False, actions=[], output=output, replay_schema=replay_schema)
 
@@ -270,13 +291,13 @@ def add_timer_fired_events(context_builder: ContextBuilder, id_: int, timestamp:
     context_builder.add_orchestrator_started_event()
     context_builder.add_timer_fired_event(id_=id_, fire_at=fire_at)
 
-def add_hello_action(state: OrchestratorState, input_: str):
-    action = CallActivityAction(function_name='Hello', input_=input_)
+def add_hello_action(state: OrchestratorState, input_: str, activity_name="Hello"):
+    action = CallActivityAction(function_name=activity_name, input_=input_)
     state.actions.append([action])
 
 def add_hello_completed_events(
-        context_builder: ContextBuilder, id_: int, result: str, is_played=False):
-    context_builder.add_task_scheduled_event(name='Hello', id_=id_)
+        context_builder: ContextBuilder, id_: int, result: str, is_played=False, activity_name="Hello"):
+    context_builder.add_task_scheduled_event(name=activity_name, id_=id_)
     context_builder.add_orchestrator_completed_event()
     context_builder.add_orchestrator_started_event()
     context_builder.add_task_completed_event(id_=id_, result=result, is_played=is_played)
@@ -365,6 +386,25 @@ def test_call_activity_with_name():
     assert_valid_schema(result)
     assert_orchestration_state_equals(expected, result)
 
+def test_call_activity_with_none_return():
+    context_builder = ContextBuilder('test_call_activity_with_none_return')
+    add_hello_completed_events(context_builder, 0, "\"Hello Tokyo!\"", "hello_return_none")
+    add_hello_completed_events(context_builder, 1, "\"Hello Seattle!\"", "hello_return_none")
+    add_hello_completed_events(context_builder, 2, None, "hello_return_none")
+    result = get_orchestration_state_result(
+        context_builder, generator_function_call_activity_with_none_return)
+
+    expected_state = base_expected_state(
+        ['Hello Tokyo!', 'Hello Seattle!', None])
+    add_hello_action(expected_state, 'Tokyo', "hello_return_none")
+    add_hello_action(expected_state, 'Seattle', "hello_return_none")
+    add_hello_action(expected_state, 'London', "hello_return_none")
+    expected_state._is_done = True
+    expected = expected_state.to_json()
+
+    assert_valid_schema(result)
+    assert_orchestration_state_equals(expected, result)
+
 def test_call_activity_function_callable_exception():
     context_builder = ContextBuilder('test_call_activity_by_name_exception')