code: def setUpClass(cls):
      cls.root_dir = cls.get_base_temp_dir()
      cls.expected = _mock_dataset(cls.root_dir, 2)
  
file_path: audio/test/torchaudio_unittest/example/souce_sepration/wsj0mix_test.py
imports: import os
  from source_separation.utils.dataset import wsj0mix
  from torchaudio_unittest.common_utils import get_whitenoise, normalize_wav, save_wav, TempDirMixin, TorchaudioTestCase
label_desc: Use image node_id 1 for calling the TestWSJ0Mix2 obj's underlying member method code with example usage: obj.setUpClass(cls) without return types