code: def setUp(self):
      self._metric = RunningMetric("test", batch_size=5, step_size=5)
      self._metric.reset({})
      self._metric._process_train = Mock(return_value=3)
      self._metric._step = Mock(return_value="output")
  
imports: import unittest
  from mock import Mock, call
  from torchbearer.metrics import RunningMean, Metric, RunningMetric, Mean, Std, Var
  import torch
label_desc: Use image node_id 1 for calling the TestRunningMetric obj's underlying member method code with example usage: obj.setUp() without return types