code: def test_contr_mlm(self, ssl_model):
      input_signal = torch.randn(size=(4, 64000))
      length = torch.randint(low=48000, high=64000, size=[4])
  
      with torch.no_grad():
          (
              spectrograms,
              spec_masks,
              encoded,
              encoded_len,
          ) = ssl_model.forward(
              input_signal=input_signal, input_signal_length=length
          )
  
      loss_value, loss_val_dict = ssl_model.decoder_loss_step(
          spectrograms, spec_masks, encoded, encoded_len
      )
  
      assert len(loss_val_dict) == 2
  
file_path: NeMo/tests/collections/asr/test_ssl_models.py
imports: import copy
  import pytest
  import torch
  from omegaconf import DictConfig, ListConfig
  from nemo.collections.asr.models import SpeechEncDecSelfSupervisedModel
label_desc: Use image node_id 3 for calling the TestSSLModel obj's underlying member method code with example usage: obj.test_contr_mlm(ssl_model) without return types