code: def setUpClass(cls):
      cls.root_dir = cls.get_base_temp_dir()
      cls.samples = get_mock_dataset(cls.root_dir)
  
file_path: audio/test/torchaudio_unittest/datasets/librispeech_test_impl.py
imports: import os
  from pathlib import Path
  from torchaudio.datasets import librispeech
  from torchaudio_unittest.common_utils import get_whitenoise, normalize_wav, save_wav, TempDirMixin
label_desc: Use image node_id 1 for calling the LibriSpeechTestMixin obj's underlying member method code with example usage: obj.setUpClass(cls) without return types