code: def test_xcom_ctor(self, dag_maker):
      python_op = build_python_op(dag_maker)
      actual = XComArg(python_op, "test_key")
      assert actual
      assert actual.operator == python_op
      assert actual.key == "test_key"
      # Asserting the overridden __eq__ method
      assert actual == XComArg(python_op, "test_key")
      expected_str = (
          "{{ task_instance.xcom_pull(task_ids='test_xcom_op', "
          "dag_id='test_xcom_dag', key='test_key') }}"
      )
      assert str(actual) == expected_str
      assert (
          f"echo {actual}"
          == "echo {{ task_instance.xcom_pull(task_ids='test_xcom_op', "
          "dag_id='test_xcom_dag', key='test_key') }}"
      )
  
imports: from __future__ import annotations
  import pytest
  from airflow.models.xcom_arg import XComArg
  from airflow.operators.bash import BashOperator
  from airflow.operators.python import PythonOperator
  from airflow.utils.types import NOTSET
  from tests.test_utils.config import conf_vars
  from tests.test_utils.db import clear_db_dags, clear_db_runs
label_desc: Use image node_id 1 for calling the TestXComArgBuild obj's underlying member method code with example usage: obj.test_xcom_ctor(dag_maker) without return types