code: def setUpClass(cls):
      env_config_path = os.path.abspath(
          os.path.join(
              os.path.dirname(__file__), "..", "..", "..", ".env"
          )
      )
      load_dotenv(env_config_path)
      # https://freewavesamples.com/yamaha-v50-rock-beat-120-bpm
      cls.sample_wav_file = os.path.join(
          os.environ.get("TEST_DIR"),
          "res",
          "audio",
          "Yamaha-V50-Rock-Beat-120bpm.wav",
      )
  
file_path: nlpaug/test/augmenter/spectrogram/test_frequency_masking.py
imports: import unittest
  import os
  import numpy
  from dotenv import load_dotenv
  from nlpaug.util import AudioLoader
  import nlpaug.augmenter.spectrogram
label_desc: Use image node_id 1 for calling the TestFrequencyMasking obj's underlying member method code with example usage: obj.setUpClass(cls) without return types