code: def test_save_ply_invalid_indices(self):
      message_regex = "Faces have invalid indices"
      verts = torch.FloatTensor([[0.1, 0.2, 0.3]])
      faces = torch.LongTensor([[0, 1, 2]])
      with self.assertWarnsRegex(UserWarning, message_regex):
          save_ply(BytesIO(), verts, faces)
  
      faces = torch.LongTensor([[-1, 0, 1]])
      with self.assertWarnsRegex(UserWarning, message_regex):
          save_ply(BytesIO(), verts, faces)
  
imports: import itertools
  import struct
  import unittest
  from io import BytesIO, StringIO
  from tempfile import NamedTemporaryFile, TemporaryFile
  import numpy
  import pytorch3d.io.ply_io
  import torch
  from iopath.common.file_io import PathManager
  from pytorch3d.io import IO
  from pytorch3d.io.ply_io import load_ply, save_ply
  from pytorch3d.renderer.mesh import TexturesVertex
  from pytorch3d.structures import Meshes, Pointclouds
  from pytorch3d.utils import torus
  from .common_testing import get_tests_dir, TestCaseMixin
label_desc: Use image node_id 9 for calling the TestMeshPlyIO obj's underlying member method code with example usage: obj.test_save_ply_invalid_indices() without return types