code: def test_voice_conversion(self):
      num_speakers = 10
      spec_len = 101
      spec_effective_len = 50
  
      args = VitsArgs(
          num_speakers=num_speakers, use_speaker_embedding=True
      )
      model = Vits(args)
  
      ref_inp = torch.randn(1, 513, spec_len)
      ref_inp_len = torch.randint(1, spec_effective_len, (1,))
      ref_spk_id = torch.randint(1, num_speakers, (1,)).item()
      tgt_spk_id = torch.randint(1, num_speakers, (1,)).item()
      o_hat, y_mask, (z, z_p, z_hat) = model.voice_conversion(
          ref_inp, ref_inp_len, ref_spk_id, tgt_spk_id
      )
  
      self.assertEqual(o_hat.shape, (1, 1, spec_len * 256))
      self.assertEqual(y_mask.shape, (1, 1, spec_len))
      self.assertEqual(y_mask.sum(), ref_inp_len[0])
      self.assertEqual(z.shape, (1, args.hidden_channels, spec_len))
      self.assertEqual(z_p.shape, (1, args.hidden_channels, spec_len))
      self.assertEqual(z_hat.shape, (1, args.hidden_channels, spec_len))
  
imports: import copy
  import os
  import unittest
  import torch
  from trainer.logging.tensorboard_logger import TensorboardLogger
  from tests import assertHasAttr, assertHasNotAttr, get_tests_data_path, get_tests_input_path, get_tests_output_path
  from TTS.config import load_config
  from TTS.encoder.utils.generic_utils import setup_encoder_model
  from TTS.tts.configs.vits_config import VitsConfig
  from TTS.tts.models.vits import Vits, VitsArgs, VitsAudioConfig, amp_to_db, db_to_amp, load_audio, spec_to_mel, wav_to_mel, wav_to_spec
  from TTS.tts.utils.speakers import SpeakerManager
label_desc: Use image node_id 6 for calling the TestVits obj's underlying member method code with example usage: obj.test_voice_conversion() without return types