code: def testPrepareBackgroundData(self):
      tmp_dir = self.get_temp_dir()
      background_dir = os.path.join(tmp_dir, "_background_noise_")
      os.mkdir(background_dir)
      wav_data = self._getWavData()
      for i in range(10):
          file_path = os.path.join(
              background_dir, "background_audio_%d.wav" % i
          )
          self._saveTestWavFile(file_path, wav_data)
      self._saveWavFolders(tmp_dir, ["a", "b", "c"], 100)
      audio_processor = input_data.AudioProcessor(
          "",
          tmp_dir,
          10,
          10,
          ["a", "b"],
          10,
          10,
          self._model_settings(),
          tmp_dir,
      )
      self.assertEqual(10, len(audio_processor.background_data))
  
imports: import os
  import numpy
  import tensorflow
  from tensorflow.examples.speech_commands import input_data
  from tensorflow.examples.speech_commands import models
  from tensorflow.python.framework import test_util
  from tensorflow.python.platform import test
label_desc: Use image node_id 11 for calling the InputDataTest obj's underlying member method code with example usage: obj.testPrepareBackgroundData() without return types