code: def test_config(self):
      mse_obj = reduction_metrics.MeanMetricWrapper(
          fn=mse, name="mse", dtype="float32"
      )
      self.assertEqual(mse_obj.name, "mse")
      self.assertEqual(len(mse_obj.variables), 2)
      self.assertEqual(mse_obj._dtype, "float32")
      # Check save and restore config
      mse_obj2 = reduction_metrics.MeanMetricWrapper.from_config(
          mse_obj.get_config()
      )
      self.assertEqual(mse_obj2.name, "mse")
      self.assertEqual(len(mse_obj2.variables), 2)
      self.assertEqual(mse_obj2._dtype, "float32")
      self.assertTrue("fn" in mse_obj2.get_config())
  
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 MetricWrapperTest obj's underlying member method code with example usage: obj.test_config() without return types