code: def test_check(self):
      im = torch.zeros(1, 2, 3)
      im_nodim = MetaTensor(im, meta={"original_channel_dim": None})
  
      with self.assertRaises(ValueError):  # not MetaTensor
          EnsureChannelFirst(channel_dim=None)(im)
      with self.assertRaises(ValueError):  # no meta
          EnsureChannelFirst(channel_dim=None)(MetaTensor(im))
      with self.assertRaises(ValueError):  # no meta channel
          EnsureChannelFirst()(im_nodim)
  
      with self.assertWarns(Warning):
          EnsureChannelFirst(strict_check=False, channel_dim=None)(im)
  
      with self.assertWarns(Warning):
          EnsureChannelFirst(strict_check=False, channel_dim=None)(
              im_nodim
          )
  
file_path: MONAI/tests/test_ensure_channel_first.py
imports: from __future__ import annotations
  import os
  import tempfile
  import unittest
  import nibabel
  import numpy
  import torch
  from parameterized import parameterized
  from PIL import Image
  from monai.data.meta_tensor import MetaTensor
  from monai.transforms import EnsureChannelFirst, LoadImage
  from monai.utils import optional_import
label_desc: Use image node_id 4 for calling the TestEnsureChannelFirst obj's underlying member method code with example usage: obj.test_check() without return types