docstr: Setup test cases for all impersonation tests.
docstr_tok: ["Setup","test","cases","for","all","impersonation","tests","."]
code: def setup_impersonation_tests(self, create_airflow_home):
      """Setup test cases for all impersonation tests."""
      db.clear_db_runs()
      db.clear_db_jobs()
      add_default_pool_if_not_exists()
      yield
      db.clear_db_runs()
      db.clear_db_jobs()
  
imports: from __future__ import annotations
  import contextlib
  import logging
  import os
  import subprocess
  import sys
  import tempfile
  from pathlib import Path
  import pytest
  from airflow.configuration import conf
  from airflow.jobs.backfill_job_runner import BackfillJobRunner
  from airflow.jobs.job import Job, run_job
  from airflow.models import DagBag, DagRun, TaskInstance
  from airflow.utils.db import add_default_pool_if_not_exists
  from airflow.utils.state import State
  from airflow.utils.timezone import datetime
  from airflow.utils.types import DagRunType
  from tests.test_utils import db
label_desc: Use image node_id 1 for calling the BaseImpersonationTest obj's underlying member method code with example usage: obj.setup_impersonation_tests(create_airflow_home) without return types