code: def test__add_third_dim_converts2_to_3_dims():
      two_d_arr = np.array([[1, 2], [3, 4]])
      three_d_arr = _add_third_dim(two_d_arr)
      assert len(three_d_arr.shape) == 3
      np.testing.assert_array_equal(two_d_arr, three_d_arr[..., 0])
      np.testing.assert_array_equal(
          three_d_arr[..., 0], three_d_arr[..., 1]
      )
      np.testing.assert_array_equal(
          three_d_arr[..., 1], three_d_arr[..., 2]
      )
  
imports: import pytest
  from pathlib import Path
  import numpy
  from PIL import Image
  from imagededup.utils.image_utils import preprocess_image, load_image, _check_3_dim, _add_third_dim, _raise_wrong_dim_value_error, check_image_array_hash, expand_image_array_cnn
label_desc: Use image node_id 3 for calling a global function with example usage: test__add_third_dim_converts2_to_3_dims() without return types