code: def test_single_input(self, test_data):
      test_data = {"img": test_data}
      result = ToTensord(keys="img", track_meta=True)(test_data)
      out_img = result["img"]
      self.assertTrue(isinstance(out_img, torch.Tensor))
      assert_allclose(out_img, test_data["img"], type_test=False)
      self.assertEqual(out_img.ndim, 0)
  
file_path: MONAI/tests/test_to_tensord.py
imports: from __future__ import annotations
  import unittest
  import numpy
  import torch
  from parameterized import parameterized
  from monai.transforms import ToTensord
  from tests.utils import HAS_CUPY, TEST_NDARRAYS, assert_allclose, optional_import
label_desc: Use image node_id 2 for calling the TestToTensord obj's underlying member method code with example usage: obj.test_single_input(test_data) without return types