code: def _test_inference(self, batch_size):
      config = FreeVCConfig()
      model = FreeVC(config).to(device)
      model.eval()
  
      _, _, mel, _, _, waveform = self._create_inputs(
          config, batch_size
      )
  
      wavlm_vec = model.extract_wavlm_features(waveform)
      wavlm_vec_lengths = torch.ones(batch_size, dtype=torch.long)
  
      output_wav = model.inference(
          wavlm_vec, None, mel, wavlm_vec_lengths
      )
      assert (
          output_wav.shape[-1] // config.audio.hop_length
          == wavlm_vec.shape[-1]
      ), f"{output_wav.shape[-1] // config.audio.hop_length} != {wavlm_vec.shape}"
  
imports: import os
  import unittest
  import torch
  from tests import get_tests_input_path
  from TTS.vc.configs.freevc_config import FreeVCConfig
  from TTS.vc.models.freevc import FreeVC
label_desc: Use image node_id 8 for calling the TestFreeVC obj's underlying member method code with example usage: obj._test_inference(batch_size) without return types