code: def test_output(self):
      train = getattr(self, "train", False)
      name = "batch_normalization"
      if not train:
          name = "fixed_" + name
      if hasattr(self, "condition"):
          name += "_" + self.condition
  
      def test_input_names(onnx_model, path):
          initializer_names = get_initializer_names(onnx_model)
          assert len(initializer_names) == 4
          assert "param_bn_avg_mean" in initializer_names
          assert "param_bn_avg_var" in initializer_names
  
      self.expect(
          self.model,
          self.x,
          name=name,
          train=train,
          custom_model_test_func=test_input_names,
      )
  
imports: import chainer
  import chainer.functions
  import chainer.links
  from chainer import testing
  import numpy
  from onnx_chainer.testing import input_generator
  from onnx_chainer_tests.helper import get_initializer_names
  from onnx_chainer_tests.helper import ONNXModelTest
label_desc: Use image node_id 2 for calling the TestBatchNormalization obj's underlying member method code with example usage: obj.test_output() without return types