fix: timeout executions based on execution timeout

src/aws_durable_execution_sdk_python_testing/executor.py

@@ -90,6 +90,7 @@ def __init__(
         self._completion_events: dict[str, Event] = {}
         self._callback_timeouts: dict[str, Future] = {}
         self._callback_heartbeats: dict[str, Future] = {}
+        self._execution_timeout: Future | None = None
 
     def start_execution(
         self,
@@ -118,6 +119,21 @@ def start_execution(
         completion_event = self._scheduler.create_event()
         self._completion_events[execution.durable_execution_arn] = completion_event
 
+        # Schedule execution timeout
+        if input.execution_timeout_seconds > 0:
+
+            def timeout_handler():
+                error = ErrorObject.from_message(
+                    f"Execution timed out after {input.execution_timeout_seconds} seconds."
+                )
+                self.on_timed_out(execution.durable_execution_arn, error)
+
+            self._execution_timeout = self._scheduler.call_later(
+                timeout_handler,
+                delay=input.execution_timeout_seconds,
+                completion_event=completion_event,
+            )
+
         # Schedule initial invocation to run immediately
         self._invoke_execution(execution.durable_execution_arn)
 
@@ -897,6 +913,9 @@ def _complete_events(self, execution_arn: str):
         # complete doesn't actually checkpoint explicitly
         if event := self._completion_events.get(execution_arn):
             event.set()
+        if self._execution_timeout:
+            self._execution_timeout.cancel()
+            self._execution_timeout = None
 
     def wait_until_complete(
         self, execution_arn: str, timeout: float | None = None