code: def test_empty_df(self):
      # -- create model --
      self.run_sql(
          """
                  CREATE model mindsdb.task_model
                  PREDICT a
                  using engine='dummy_ml',
                  join_learn_process=true
              """
      )
      self.wait_predictor("mindsdb", "task_model")
  
imports: from unittest.mock import patch
  import datetime
  import time
  import pytest
  import pandas
  from mindsdb_sql import parse_sql
  from .executor_test_base import BaseExecutorDummyML
label_desc: Use image node_id 6 for calling the TestProjectStructure obj's underlying member method code with example usage: obj.test_empty_df() without return types