code: def test_abstract_plan_str(self):
      derived_plan_classes = list(get_all_subclasses(AbstractPlan))
      for derived_plan_class in derived_plan_classes:
          sig = signature(derived_plan_class.__init__)
          params = sig.parameters
          plan_dict = {}
          if isabstract(derived_plan_class) is False:
              obj = get_mock_object(derived_plan_class, len(params))
              plan_dict[obj] = obj
  
imports: import unittest
  from inspect import isabstract, signature
  from test.util import get_all_subclasses, get_mock_object
  import pytest
  from evadb.catalog.catalog_type import ColumnType
  from evadb.catalog.models.column_catalog import ColumnCatalogEntry
  from evadb.parser.table_ref import TableInfo, TableRef
  from evadb.parser.types import FileFormatType, ObjectType
  from evadb.plan_nodes.abstract_plan import AbstractPlan
  from evadb.plan_nodes.create_function_plan import CreateFunctionPlan
  from evadb.plan_nodes.create_plan import CreatePlan
  from evadb.plan_nodes.drop_object_plan import DropObjectPlan
  from evadb.plan_nodes.insert_plan import InsertPlan
  from evadb.plan_nodes.load_data_plan import LoadDataPlan
  from evadb.plan_nodes.rename_plan import RenamePlan
  from evadb.plan_nodes.types import PlanOprType
  from evadb.plan_nodes.union_plan import UnionPlan
label_desc: Use image node_id 9 for calling the PlanNodeTests obj's underlying member method code with example usage: obj.test_abstract_plan_str() without return types