code: def init_class_fixtures(cls):
      super(TestTestingSlippage, cls).init_class_fixtures()
      cls.asset = cls.asset_finder.retrieve_asset(1)
      cls.minute, _ = cls.trading_calendar.open_and_close_for_session(
          cls.START_DATE
      )
  
imports: from itertools import product
  from unittest import TestCase
  from numpy import array, empty
  from zipline._protocol import BarData
  from zipline.finance.asset_restrictions import NoRestrictions
  from zipline.finance.order import Order
  from zipline.testing import check_arrays, make_alternating_boolean_array, make_cascading_boolean_array, parameter_space
  from zipline.testing.fixtures import WithConstantEquityMinuteBarData, WithDataPortal, ZiplineTestCase
  from zipline.testing.slippage import TestingSlippage
  from zipline.testing.predicates import wildcard, instance_of
  from zipline.utils.numpy_utils import bool_dtype
label_desc: Use image node_id 1 for calling the TestTestingSlippage obj's underlying member method code with example usage: obj.init_class_fixtures(cls) without return types