code: def test_output(self):
      test_cases = ["matrix", "vector"]
      if not self.op_name.startswith("MatMul"):
          test_cases.append("scalar")
  
      for tc in test_cases:
          xs = getattr(self, tc)()
          name = "{}_{}".format(self.op_name.lower(), tc)
          self.expect(
              self.get_model(),
              xs,
              name=name,
              expected_num_initializers=0,
          )
  
imports: import chainer
  import chainer.functions
  from chainer import testing
  from chainer.testing import attr
  import numpy
  import pytest
  from onnx_chainer.testing import input_generator
  from onnx_chainer_tests.helper import ONNXModelTest
label_desc: Use image node_id 2 for calling the TestBinaryMathOperators obj's underlying member method code with example usage: obj.test_output() without return types