Update isReplaying flag at beginning of replay

azure/durable_functions/models/TaskOrchestrationExecutor.py

@@ -68,6 +68,22 @@ def execute(self, context: DurableOrchestrationContext,
         self.context = context
         evaluated_user_code = fn(context)
 
+        # The minimum History size is 2, in the shape: [OrchestratorStarted, ExecutionStarted].
+        # At the start of replay, the `is_replaying` flag is determined from the
+        # ExecutionStarted event.
+        # For some reason, OrchestratorStarted does not update its `isPlayed` field.
+        if len(history) < 2:
+            err_message = "Internal Durable Functions error: "\
+                + f"received History array of size {len(history)} "\
+                + "when a minimum size of 2 is expected. "\
+                + "Please report this issue at "\
+                + "https://github.com/Azure/azure-functions-durable-python/issues."
+            raise Exception(err_message)
+
+        # Set initial is_replaing state.
+        execution_started_event = history[1]
+        self.current_task.is_played = execution_started_event.is_played
+
         # If user code is a generator, then it uses `yield` statements (the DF API)
         # and so we iterate through the DF history, generating tasks and populating
         # them with values when the history provides them

tests/orchestrator/test_is_replaying_flag.py

@@ -47,7 +47,7 @@ def add_timer_action(state: OrchestratorState, fire_at: datetime):
 
 def test_is_replaying_initial_value():
 
-    context_builder = ContextBuilder("")
+    context_builder = ContextBuilder("", is_replaying=False)
     result = get_orchestration_property(
         context_builder, generator_function, "durable_context")
 

tests/orchestrator/test_sequential_orchestrator.py

@@ -24,6 +24,17 @@ def generator_function(context):
 
     return outputs
 
+def generator_function_is_replaying(context):
+    outputs = []
+
+    outputs.append(context.is_replaying)
+    yield context.call_activity("Hello", "Tokyo")
+    outputs.append(context.is_replaying)
+    yield context.call_activity("Hello", "Seattle")
+    outputs.append(context.is_replaying)
+    yield context.call_activity("Hello", "London")
+    return outputs
+
 def generator_function_no_yield(context):
     outputs = []
 
@@ -150,11 +161,11 @@ def add_hello_action(state: OrchestratorState, input_: str):
     state.actions.append([action])
 
 def add_hello_completed_events(
-        context_builder: ContextBuilder, id_: int, result: str):
+        context_builder: ContextBuilder, id_: int, result: str, is_played=False):
     context_builder.add_task_scheduled_event(name='Hello', id_=id_)
     context_builder.add_orchestrator_completed_event()
     context_builder.add_orchestrator_started_event()
-    context_builder.add_task_completed_event(id_=id_, result=result)
+    context_builder.add_task_completed_event(id_=id_, result=result, is_played=is_played)
 
 
 def add_hello_failed_events(
@@ -286,6 +297,26 @@ def test_tokyo_and_seattle_and_london_state():
     assert_valid_schema(result)
     assert_orchestration_state_equals(expected, result)
 
+def test_sequential_is_replaying():
+    context_builder = ContextBuilder('test_simple_function', is_replaying=True)
+    add_hello_completed_events(context_builder, 0, "\"Hello Tokyo!\"", True)
+    add_hello_completed_events(context_builder, 1, "\"Hello Seattle!\"", True)
+    add_hello_completed_events(context_builder, 2, "\"Hello London!\"", True)
+
+    result = get_orchestration_state_result(
+        context_builder, generator_function_is_replaying)
+
+    expected_state = base_expected_state(
+        [True, True, True])
+    add_hello_action(expected_state, 'Tokyo')
+    add_hello_action(expected_state, 'Seattle')
+    add_hello_action(expected_state, 'London')
+    expected_state._is_done = True
+    expected = expected_state.to_json()
+
+    assert_valid_schema(result)
+    assert_orchestration_state_equals(expected, result)
+
 def test_sequential_orchestration_no_yield():
     context_builder = ContextBuilder('test_simple_function')
     add_hello_completed_events(context_builder, 0, "\"Hello London!\"")

tests/test_utils/ContextBuilder.py

@@ -14,7 +14,7 @@
 
 
 class ContextBuilder:
-    def __init__(self, name: str="", increase_time: bool = True, starting_time: Optional[datetime] = None, replay_schema: ReplaySchema = ReplaySchema.V1):
+    def __init__(self, name: str="", increase_time: bool = True, starting_time: Optional[datetime] = None, is_replaying=False, replay_schema: ReplaySchema = ReplaySchema.V1):
         self.increase_time = increase_time
         self.instance_id = uuid.uuid4()
         self.is_replaying: bool = False
@@ -28,7 +28,7 @@ def __init__(self, name: str="", increase_time: bool = True, starting_time: Opti
         self.upperSchemaVersion = replay_schema.value
 
         self.add_orchestrator_started_event()
-        self.add_execution_started_event(name)
+        self.add_execution_started_event(name, is_played=is_replaying)
 
     def get_base_event(
             self, event_type: HistoryEventType, id_: int = -1,
@@ -87,8 +87,8 @@ def add_task_scheduled_event(
         event.Input_ = input_
         self.history_events.append(event)
 
-    def add_task_completed_event(self, id_: int, result):
-        event = self.get_base_event(HistoryEventType.TASK_COMPLETED)
+    def add_task_completed_event(self, id_: int, result, is_played=False):
+        event = self.get_base_event(HistoryEventType.TASK_COMPLETED, is_played=is_played)
         event.Result = result
         event.TaskScheduledId = id_
         self.history_events.append(event)
@@ -116,8 +116,8 @@ def add_timer_fired_event(self, id_: int, fire_at: str, is_played: bool = True):
         self.history_events.append(event)
 
     def add_execution_started_event(
-            self, name: str, version: str = '', input_=None):
-        event = self.get_base_event(HistoryEventType.EXECUTION_STARTED, is_played=True)
+            self, name: str, version: str = '', input_=None, is_played=True):
+        event = self.get_base_event(HistoryEventType.EXECUTION_STARTED, is_played=is_played)
         event.orchestration_instance = OrchestrationInstance()
         self.instance_id = event.orchestration_instance.instance_id
         event.Name = name