code: def validate(self) -> None:
      if (
          database_name := self._properties.get("database_name")
      ) is not None:
          self._model = DatabaseDAO.get_database_by_name(database_name)
  
imports: import logging
  import sqlite3
  from contextlib import closing
  from typing import Any, Optional
  from flask import current_app
  from flask_babel import gettext
  from func_timeout import func_timeout, FunctionTimedOut
  from sqlalchemy.engine import Engine
  from sqlalchemy.exc import DBAPIError, NoSuchModuleError
  from superset import is_feature_enabled
  from superset.commands.base import BaseCommand
  from superset.commands.database.exceptions import DatabaseSecurityUnsafeError, DatabaseTestConnectionDriverError, DatabaseTestConnectionUnexpectedError
  from superset.commands.database.ssh_tunnel.exceptions import SSHTunnelingNotEnabledError
  from superset.daos.database import DatabaseDAO, SSHTunnelDAO
  from superset.databases.ssh_tunnel.models import SSHTunnel
  from superset.databases.utils import make_url_safe
  from superset.errors import ErrorLevel, SupersetErrorType
  from superset.exceptions import SupersetErrorsException, SupersetSecurityException, SupersetTimeoutException
  from superset.extensions import event_logger
  from superset.models.core import Database
  from superset.utils.ssh_tunnel import unmask_password_info
label_desc: Use image node_id 3 for calling the TestConnectionDatabaseCommand obj's underlying member method code with example usage: obj.validate() without return types