docstr: Tests that method will throw error if color is not poresent.
code: def test_prase_vertex_expects_colors(self):
      """Tests that method will throw error if color is not poresent."""
      with self.assertRaisesRegex(
          ValueError, "PLY file must contain vertices with colors"
      ):
          demo_utils._parse_vertex("1 2 3")
  
file_path: tensorboard/tensorboard/plugins/mesh/demo_utils_test.py
imports: import os
  import tensorflow
  from tensorboard.plugins.mesh import demo_utils
label_desc: Use image node_id 2 for calling the TestPLYReader obj's underlying member method code with example usage: obj.test_prase_vertex_expects_colors() without return types