def METHOD_NAME(mocker, policy_arn, expected_get_policy_side_effect, expected_message):
    mock_aws_api(mocker)
    mocker.patch("pcluster.aws.iam.IamClient.get_policy", side_effect=expected_get_policy_side_effect)
    actual_failures = AdditionalIamPolicyValidator().execute(policy=policy_arn)
    assert_failure_messages(actual_failures, expected_message)