How to use the bless.config.bless_config.USERNAME_VALIDATION_OPTION function in bless

def test_validate_multiple_principals(test_input):
    BlessSchema().validate_remote_usernames(test_input)

    schema = BlessSchema()
    schema.context[USERNAME_VALIDATION_OPTION] = USERNAME_VALIDATION_OPTIONS.principal.name
    schema.context[REMOTE_USERNAMES_VALIDATION_OPTION] = USERNAME_VALIDATION_OPTIONS.principal.name
    schema.context[REMOTE_USERNAMES_BLACKLIST_OPTION] = 'balrog'
    schema.validate_remote_usernames(test_input)

'kms_auth_kmsauth_serviceid': 'bless-test',
    }

    for k, v in extra_environment_variables.items():
        monkeypatch.setenv(k, v)

    # Create an empty config, everything is set in the environment
    config = BlessConfig('us-east-1', config_file='')

    assert 1 == config.getint(BLESS_OPTIONS_SECTION, CERTIFICATE_VALIDITY_AFTER_SEC_OPTION)
    assert 1 == config.getint(BLESS_OPTIONS_SECTION, CERTIFICATE_VALIDITY_BEFORE_SEC_OPTION)
    assert 2 == config.getint(BLESS_OPTIONS_SECTION, ENTROPY_MINIMUM_BITS_OPTION)
    assert 3 == config.getint(BLESS_OPTIONS_SECTION, RANDOM_SEED_BYTES_OPTION)
    assert 'DEBUG' == config.get(BLESS_OPTIONS_SECTION, LOGGING_LEVEL_OPTION)
    assert 'permit-X11-forwarding' == config.get(BLESS_OPTIONS_SECTION, CERTIFICATE_EXTENSIONS_OPTION)
    assert 'debian' == config.get(BLESS_OPTIONS_SECTION, USERNAME_VALIDATION_OPTION)
    assert 'useradd' == config.get(BLESS_OPTIONS_SECTION, REMOTE_USERNAMES_VALIDATION_OPTION)

    assert '' == config.getpassword()
    assert '' == config.get(BLESS_CA_SECTION, CA_PRIVATE_KEY_FILE_OPTION)
    assert b'' == config.getprivatekey()

    assert config.getboolean(KMSAUTH_SECTION, KMSAUTH_USEKMSAUTH_OPTION)
    assert '' == config.get(KMSAUTH_SECTION, KMSAUTH_KEY_ID_OPTION)
    assert 'bless-test' == config.get(KMSAUTH_SECTION, KMSAUTH_SERVICE_ID_OPTION)

    config.aws_region = 'invalid'
    assert '' == config.getpassword()

def test_configs(config, region, expected_cert_valid, expected_entropy_min, expected_rand_seed,
                 expected_log_level, expected_password, expected_username_validation, expected_key_compression):
    config = BlessConfig(region, config_file=config)
    assert expected_cert_valid == config.getint(BLESS_OPTIONS_SECTION,
                                                CERTIFICATE_VALIDITY_BEFORE_SEC_OPTION)
    assert expected_cert_valid == config.getint(BLESS_OPTIONS_SECTION,
                                                CERTIFICATE_VALIDITY_AFTER_SEC_OPTION)

    assert expected_entropy_min == config.getint(BLESS_OPTIONS_SECTION,
                                                 ENTROPY_MINIMUM_BITS_OPTION)
    assert expected_rand_seed == config.getint(BLESS_OPTIONS_SECTION,
                                               RANDOM_SEED_BYTES_OPTION)
    assert expected_log_level == config.get(BLESS_OPTIONS_SECTION, LOGGING_LEVEL_OPTION)
    assert expected_password == config.getpassword()
    assert expected_username_validation == config.get(BLESS_OPTIONS_SECTION,
                                                      USERNAME_VALIDATION_OPTION)
    assert expected_key_compression == config.get(BLESS_CA_SECTION,
                                                  CA_PRIVATE_KEY_COMPRESSION_OPTION)

logger = logging.getLogger()
    logger.setLevel(numeric_level)

    certificate_validity_before_seconds = config.getint(BLESS_OPTIONS_SECTION,
                                                        CERTIFICATE_VALIDITY_BEFORE_SEC_OPTION)
    certificate_validity_after_seconds = config.getint(BLESS_OPTIONS_SECTION,
                                                       CERTIFICATE_VALIDITY_AFTER_SEC_OPTION)
    entropy_minimum_bits = config.getint(BLESS_OPTIONS_SECTION, ENTROPY_MINIMUM_BITS_OPTION)
    random_seed_bytes = config.getint(BLESS_OPTIONS_SECTION, RANDOM_SEED_BYTES_OPTION)
    ca_private_key = config.getprivatekey()
    certificate_extensions = config.get(BLESS_OPTIONS_SECTION, CERTIFICATE_EXTENSIONS_OPTION)

    # Process cert request
    schema = BlessSchema(strict=True)
    schema.context[USERNAME_VALIDATION_OPTION] = config.get(BLESS_OPTIONS_SECTION, USERNAME_VALIDATION_OPTION)
    schema.context[REMOTE_USERNAMES_VALIDATION_OPTION] = config.get(BLESS_OPTIONS_SECTION,
                                                                    REMOTE_USERNAMES_VALIDATION_OPTION)
    schema.context[REMOTE_USERNAMES_BLACKLIST_OPTION] = config.get(BLESS_OPTIONS_SECTION,
                                                                   REMOTE_USERNAMES_BLACKLIST_OPTION)

    try:
        request = schema.load(event).data
    except ValidationError as e:
        return error_response('InputValidationError', str(e))

    logger.info('Bless lambda invoked by [user: {0}, bastion_ips:{1}, public_key: {2}, kmsauth_token:{3}]'.format(
        request.bastion_user,
        request.bastion_user_ip,
        request.public_key_to_sign,
        request.kmsauth_token))

def validate_bastion_user(self, user):
        if USERNAME_VALIDATION_OPTION in self.context:
            username_validation = USERNAME_VALIDATION_OPTIONS[self.context[USERNAME_VALIDATION_OPTION]]
        else:
            username_validation = USERNAME_VALIDATION_OPTIONS[USERNAME_VALIDATION_DEFAULT]
        validate_user(user, username_validation)