dag.test "mark_success_pattern" could work nicer with dynamically mapped tasks

### Apache Airflow version Other Airflow 3 version (please specify below) ### If "Other Airflow 3 version" selected, which one? 3.1.2 ### What happened? `Cannot expand <SerializedMappedTask(PythonOperator): process_item> for run manual__2026-02-06T19:06:43.772890+00:00; missing upstream values: ['op_args']` This occurs whenever you run `dag.test()` and provide a `mark_success_pattern` for the upstream task to the dynamic operator. The dynamic task has no input values to map over, and predictably fails. What could be considered a bug, is the same error still occurs when you ALSO provide a `mark_success_pattern` for the dynamic task itself. ### What you think should happen instead? I would prefer if the test function were smart enough to check for tasks it should auto-succeed, **including dynamic tasks**, before checking for "missing upstream values." One difficulty is a task still needs to be generated, but it should be simple enough to generate a single successful mapped task. (The more I think about this, the more I think it is a feature request and not a bug, but hey 🤷 ). ### How to reproduce ``` from airflow import DAG from airflow.providers.standard.operators.python import PythonOperator def generate_list(): return [["item1"], ["item2"], ["item3"]] def process_item(item): print(f"Processing {item}") with DAG( dag_id="test_dynamic_mapping_dag", default_args={"owner": "airflow"}, schedule=None, ) as dag: generate_task = PythonOperator( task_id="generate_list", python_callable=generate_list, ) process_task = PythonOperator.partial( task_id="process_item", python_callable=process_item, ).expand(op_args=generate_task.output) if __name__ == "__main__": # running the below will understandably fail # dag.test(mark_success_pattern="generate_list") # running the below will fail, but arguably should succeed dag.test(mark_success_pattern="generate_list|process_item") ``` ### Operating Syst…