code: def test_category_name(self):
      labels = metadata_writer.Labels()
      self.assertEqual(
          labels.add(["a", "b"])._labels,
          [
              metadata_writer.LabelItem(
                  filename="labels.txt", names=["a", "b"], locale=None
              )
          ],
      )
  
imports: import os
  import tempfile
  from absl.testing import absltest
  from mediapipe.tasks.metadata import metadata_schema_py_generated
  from mediapipe.tasks.python.metadata.metadata_writers import metadata_info
  from mediapipe.tasks.python.metadata.metadata_writers import metadata_writer
  from mediapipe.tasks.python.test import test_utils
label_desc: Use image node_id 1 for calling the LabelsTest obj's underlying member method code with example usage: obj.test_category_name() without return types