code: def test_invalid_format_non_exist(self, backend):
      non_exist_filename = self.model_path_h5.replace(
          ".h5", "_non_exist.h5"
      )
      with pytest.raises(ValueError) as e:
          converter.convert(
              non_exist_filename, source=frontend, convert_to=backend[0]
          )
      e.match(r"Input model .* does not exist")
  
imports: import os
  import shutil
  import tempfile
  import pytest
  import coremltools.converters
  from coremltools.converters.mil.frontend.tensorflow.test.test_load import frontend
  from coremltools.converters.mil.frontend.tensorflow.test.testing_utils import get_tf_keras_io_names
  from coremltools.converters.mil.input_types import TensorType
  from coremltools.converters.mil.testing_reqs import backends
label_desc: Use image node_id 16 for calling the TestTf2ModelFormats obj's underlying member method code with example usage: obj.test_invalid_format_non_exist(backend) without return types