code: def test_convert_audio_channels_downmix(self):
      b, c, dur = 2, 3, 4.0
      sr = 128
      audio = get_batch_white_noise(b, c, int(sr * dur))
      out = convert_audio(
          audio, from_rate=sr, to_rate=sr, to_channels=2
      )
      assert list(out.shape) == [audio.shape[0], 2, audio.shape[-1]]
  
file_path: audiocraft/tests/data/test_audio_utils.py
imports: import julius
  import torch
  import pytest
  from audiocraft.data.audio_utils import _clip_wav, convert_audio_channels, convert_audio, normalize_audio
  from ..common_utils import get_batch_white_noise
label_desc: Use image node_id 1 for calling the TestConvertAudio obj's underlying member method code with example usage: obj.test_convert_audio_channels_downmix() without return types