code: def test_get_kerberos_principle_resolve_null_principal(
      self, get_madantory_value_mock, get_hostname_mock
  ):
      principal = get_kerberos_principle(principal=None)
      assert principal == "test-principal/REPLACEMENT_HOST"
  
file_path: airflow/tests/security/test_kerberos.py
imports: from __future__ import annotations
  import logging
  import shlex
  from unittest import mock
  import pytest
  from airflow.security import kerberos
  from airflow.security.kerberos import get_kerberos_principle, renew_from_kt
  from tests.test_utils.config import conf_vars
label_desc: Use image node_id 8 for calling the TestKerberos obj's underlying member method code with example usage: obj.test_get_kerberos_principle_resolve_null_principal(get_madantory_value_mock, get_hostname_mock) without return types