class_docstr: Set up executor: mock data handler
code: def set_handler(self, mock_handler, name, tables, engine="postgres"):
      # integration
      # delete by name
      r = self.db.Integration.query.filter_by(name=name).first()
      if r is not None:
          self.db.session.delete(r)
  
      # create
      r = self.db.Integration(name=name, data={}, engine=engine)
      self.db.session.add(r)
      self.db.session.commit()
  
      from mindsdb.integrations.libs.response import RESPONSE_TYPE
      from mindsdb.integrations.libs.response import (
          HandlerResponse as Response,
      )
  
      def handler_response(df):
          response = Response(RESPONSE_TYPE.TABLE, df)
          return response
  
      def get_tables_f():
          tables_ar = []
          for table in tables:
              tables_ar.append(
                  {
                      "table_schema": "public",
                      "table_name": table,
                      "table_type": "BASE TABLE",
                  }
              )
  
          return handler_response(
              pd.DataFrame(
                  [
                      {
                          "table_schema": "public",
                          "table_name": "table1",
                          "table_type": "BASE TABLE",
                      }
                  ]
              )
          )
  
      mock_handler().get_tables.side_effect = get_tables_f
  
      def get_columns_f(table_name):
          type = "varchar"
          cols = []
          for col, typ in tables[table_name].dtypes.items():
              if pd.api.types.is_integer_dtype(typ):
                  type = "integer"
              elif pd.api.types.is_float_dtype(typ):
                  type = "float"
              elif pd.api.types.is_datetime64_dtype(typ):
                  type = "datetime"
              cols.append({"Field": col, "Type": type})
          return handler_response(pd.DataFrame(cols))
  
      mock_handler().get_columns.side_effect = get_columns_f
  
      # use duckdb to execute query for integrations
      def native_query_f(query):
          con = duckdb.connect(database=":memory:")
  
          for table, df in tables.items():
              con.register(table, df)
          try:
              result_df = con.execute(query).fetchdf()
              result_df = result_df.replace({np.nan: None})
          except Exception:
              # it can be not supported command like update or insert
              result_df = pd.DataFrame()
          for table in tables.keys():
              con.unregister(table)
  
          con.close()
          return handler_response(result_df)
  
      def query_f(query):
          renderer = SqlalchemyRender("postgres")
          query_str = renderer.get_string(query, with_failback=True)
          return native_query_f(query_str)
  
      mock_handler().native_query.side_effect = native_query_f
  
      mock_handler().query.side_effect = query_f
  
imports: import copy
  import datetime
  import json
  import os
  import sys
  import tempfile
  from unittest import mock
  from pathlib import Path
  import duckdb
  import numpy
  import pandas
  from mindsdb_sql.render.sqlalchemy_render import SqlalchemyRender
  from mindsdb_sql import parse_sql
label_desc: Use image node_id 4 for calling the BaseExecutorTest obj's underlying member method code with example usage: obj.set_handler(mock_handler, name, tables, engine) and returns: response, handler_response, handler_response, handler_response, native_query_f