text: """Unit tests for the :func:`esmvalcore.preprocessor._other` module."""
  
  import unittest
  
  import iris.coord_categorisation
  import iris.coords
  import numpy as np
  from cf_units import Unit
  from iris.cube import Cube
  from numpy.testing import assert_array_equal
  
  from esmvalcore.preprocessor import PreprocessorFile
  from esmvalcore.preprocessor._other import _group_products, clip
  
  
  class TestOther(unittest.TestCase):
      """Test class for _other."""
      def test_clip(self):
          """Test clip function."""
          cube = Cube(np.array([-10, 0, 10]))
          cube.add_dim_coord(
              iris.coords.DimCoord(
                  np.arange(3),
                  standard_name='time',
                  units=Unit('days since 1950-01-01 00:00:00',
                             calendar='gregorian'),
              ),
              0,
          )
          # Cube needs to be copied, since it is modified in-place and test cube
          # should not change.
          assert_array_equal(clip(cube.copy(), 0, None).data,
                             np.array([0, 0, 10]))
          assert_array_equal(clip(cube.copy(), None, 0).data,
                             np.array([-10, 0, 0]))
          assert_array_equal(clip(cube.copy(), -1, 2).data,
                             np.array([-1, 0, 2]))
          # Masked cube TODO
          # No parameters specified
          with self.assertRaises(ValueError):
              clip(cube, None, None)
          # Maximum lower than minimum
          with self.assertRaises(ValueError):
              clip(cube, 10, 8)
  
  
  def test_group_products_string_list():
      products = [
          PreprocessorFile(
              attributes={
                  'project': 'A',
                  'dataset': 'B',
                  'filename': 'A_B.nc'},
              settings={}),
          PreprocessorFile(
              attributes={
                  'project': 'A',
                  'dataset': 'C',
                  'filename': 'A_C.nc'},
              settings={})
      ]
      grouped_by_string = _group_products(products, 'project')
      grouped_by_list = _group_products(products, ['project'])
  
      assert grouped_by_list == grouped_by_string
  
  
  if __name__ == '__main__':
      unittest.main()
  