code: def test_running_mean_metric_class(self):
      metric = metrics.Metric
      out = metrics.running_mean(batch_size=40, step_size=20, dim=10)(
          metric
      )("test")
      self.assertTrue(isinstance(out, metrics.MetricTree))
      self.assertTrue(isinstance(out.children[0], metrics.ToDict))
      self.assertTrue(
          isinstance(out.children[0].metric, metrics.RunningMean)
      )
      self.assertTrue(out.children[0].metric._batch_size == 40)
      self.assertTrue(out.children[0].metric._step_size == 20)
      self.assertTrue(out.children[0].metric._kwargs["dim"] == 10)
      self.assertTrue(out.children[0].metric.name == "running_test")
      self.assertTrue(out.root.name == "test")
  
imports: import unittest
  from mock import Mock
  import torchbearer.metrics
  from torchbearer.metrics import default_for_key, lambda_metric, EpochLambda, BatchLambda
label_desc: Use image node_id 14 for calling the TestDecorators obj's underlying member method code with example usage: obj.test_running_mean_metric_class() without return types