code: def test_get_metrics(self):
      class FakeModel(Model):
          def forward(self, **kwargs):
              return {}
  
      model = FakeModel(None)
      total_loss = 100.0
      batch_loss = 10.0
      num_batches = 2
      metrics = get_metrics(
          model, total_loss, None, batch_loss, None, num_batches
      )
  
      assert metrics["loss"] == float(total_loss / num_batches)
      assert metrics["batch_loss"] == batch_loss
  
      metrics = get_metrics(
          model, total_loss, None, None, None, num_batches
      )
  
      assert metrics["loss"] == float(total_loss / num_batches)
      assert "batch_loss" not in metrics
  
imports: import logging
  import os
  import pickle
  import pytest
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.params import Params
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data.instance import Instance
  from allennlp.data.dataset_readers import DatasetReader
  from allennlp.data.fields import LabelField
  from allennlp.models import Model
  from allennlp.training.util import make_vocab_from_params, get_metrics
label_desc: Use image node_id 8 for calling the TestMakeVocabFromParams obj's underlying member method code with example usage: obj.test_get_metrics() and returns: dict