code: def test_config(self):
      sum_obj = reduction_metrics.Sum(name="sum", dtype="float32")
      self.assertEqual(sum_obj.name, "sum")
      self.assertEqual(len(sum_obj.variables), 1)
      self.assertEqual(sum_obj._dtype, "float32")
  
      # Check save and restore config
      sum_obj2 = reduction_metrics.Sum.from_config(sum_obj.get_config())
      self.assertEqual(sum_obj2.name, "sum")
      self.assertEqual(len(sum_obj2.variables), 1)
      self.assertEqual(sum_obj2._dtype, "float32")
  
imports: import numpy
  from keras import testing
  from keras.metrics import reduction_metrics
  from keras.saving import register_keras_serializable
label_desc: Use image node_id 1 for calling the SumTest obj's underlying member method code with example usage: obj.test_config() without return types