code: def init_class_fixtures(cls):
      super(BenchmarkSpecTestCase, cls).init_class_fixtures()
  
      zero_returns_index = pd.date_range(
          cls.START_DATE,
          cls.END_DATE,
          freq="D",
          tz="utc",
      )
      cls.zero_returns = pd.Series(index=zero_returns_index, data=0.0)
  
imports: import logbook
  import numpy
  import pandas
  from pandas.util.testing import assert_series_equal
  from zipline.data.data_portal import DataPortal
  from zipline.errors import BenchmarkAssetNotAvailableTooEarly, BenchmarkAssetNotAvailableTooLate, InvalidBenchmarkAsset
  from zipline.sources.benchmark_source import BenchmarkSource
  from zipline.utils.run_algo import BenchmarkSpec
  from zipline.testing import MockDailyBarReader, create_minute_bar_data, parameter_space, tmp_bcolz_equity_minute_bar_reader
  from zipline.testing.predicates import assert_equal
  from zipline.testing.fixtures import WithAssetFinder, WithDataPortal, WithSimParams, WithTmpDir, WithTradingCalendars, ZiplineTestCase
  from zipline.testing.core import make_test_handler
label_desc: Use image node_id 1 for calling the BenchmarkSpecTestCase obj's underlying member method code with example usage: obj.init_class_fixtures(cls) without return types