code: def test_save(self, available_backends, expected_backend):
      src = torch.zeros((2, 10))
      filename = "test.wav"
      format = "wav"
      sample_rate = 16000
      with patch(
          "torchaudio._backend.utils.get_available_backends",
          return_value=available_backends,
      ), patch(
          f"torchaudio._backend.utils.{expected_backend.__name__}.save"
      ) as mock_save:
          get_save_func()(filename, src, sample_rate, format=format)
          mock_save.assert_called_once_with(
              filename,
              src,
              sample_rate,
              True,
              format,
              None,
              None,
              4096,
              None,
          )
  
file_path: audio/test/torchaudio_unittest/backend/dispatcher/dispatcher_test.py
imports: import io
  from unittest.mock import patch
  import torch
  from parameterized import parameterized
  from torchaudio._backend.utils import FFmpegBackend, get_info_func, get_load_func, get_save_func, SoundfileBackend, SoXBackend
  from torchaudio_unittest.common_utils import PytorchTestCase
label_desc: Use image node_id 5 for calling the DispatcherTest obj's underlying member method code with example usage: obj.test_save(available_backends, expected_backend) without return types