docstr: soundfile_backend.save passes default format and subtype (None-s) to
  soundfile.write when not WAV
docstr_tok: ["soundfile_backend.save","passes","default","format","and","subtype","(","None-s",")","to","soundfile.write","when","not","WAV"]
code: def test_flac(
      self,
      dtype,
      sample_rate,
      num_channels,
      channels_first,
      bits_per_sample,
  ):
      """soundfile_backend.save passes default format and subtype (None-s) to
      soundfile.write when not WAV"""
      self.assert_non_wav(
          "flac",
          dtype,
          sample_rate,
          num_channels,
          channels_first,
          bits_per_sample=bits_per_sample,
      )
  
imports: import io
  from unittest.mock import patch
  from torchaudio._internal import module_utils
  from torchaudio.backend import soundfile_backend
  from torchaudio_unittest.common_utils import get_wav_data, load_wav, nested_params, PytorchTestCase, skipIfNoModule, TempDirMixin
  from .common import fetch_wav_subtype, parameterize, skipIfFormatNotSupported
label_desc: Use image node_id 4 for calling the MockedSaveTest obj's underlying member method code with example usage: obj.test_flac(dtype, sample_rate, num_channels, channels_first, bits_per_sample) without return types