code: def run(self):
      from dvc.config import Config
      from dvc.database import client
      from dvc.exceptions import DvcException
  
      connection = self.args.conn
      db_config = Config.from_cwd().get("db", {})
      if connection not in db_config:
          raise DvcException(
              f"connection {connection} not found in config"
          )
  
      config = db_config.get(connection, {})
      if self.args.url:
          config["url"] = self.args.url
      if self.args.username:
          config["username"] = self.args.username
      if self.args.password:
          config["password"] = self.args.password
      with client(config) as db:
          ui.write(f"Testing with {db}", styled=True)
          db.test_connection()
      ui.write("Connection successful", styled=True)
  
file_path: dvc/dvc/commands/imp_db.py
imports: from dvc.cli import completion, formatter
  from dvc.cli.command import CmdBase, CmdBaseNoRepo
  from dvc.cli.utils import append_doc_link
  from dvc.log import logger
  from dvc.ui import ui
label_desc: Use image node_id 1 for calling the CmdTestDb obj's underlying member method code with example usage: obj.run() without return types