message: [testconn] Explicit closing engine connection
diff: # specific language governing permissions and limitations
  # under the License.
  # pylint: disable=C,R,W
  +from contextlib import closing
  from datetime import datetime, timedelta
  import inspect
  import logging
  @@ -37,7 +38,7 @@ from flask_babel import lazy_gettext as _
  import pandas as pd
  import simplejson as json
  import sqlalchemy as sqla
  -from sqlalchemy import and_, create_engine, MetaData, or_, update
  +from sqlalchemy import and_, create_engine, MetaData, or_, select, update
  from sqlalchemy.engine.url import make_url
  from sqlalchemy.exc import IntegrityError
  from werkzeug.routing import BaseConverter
  @@ -1813,8 +1814,9 @@ class Superset(BaseSupersetView):
  connect_args['configuration'] = configuration
  engine = create_engine(uri, **engine_params)
  - engine.connect()
  - return json_success(json.dumps(engine.table_names(), indent=4))
  +
  + with closing(engine.connect()) as conn:
  + return json_success(json.dumps(conn.scalar(select([1]))))
  except Exception as e:
  logging.exception(e)
  return json_error_response((
  