def METHOD_NAME(self):
    input_data = ['Look at the bright sky.',
                  'His expression went dark.',
                  'The bread got hard after sitting out.',
                  'The butter got soft in the sun.',
                  'Her eyes were light blue.',
                  'The morning fog made everything damp with mist.',
                  'He cut the fence pickets short by mistake.',
                  'Charles made weak crying noises.',
                  'The black oil got on the white dog.']
    index_data = [-2, -1, 3, 3, -2, -3, 5, 2, 1]
    result_data = ['brighten', 'darken', 'harden', 'soften',
                   'lighten', 'dampen', 'shorten', 'weaken', 'blacken']
    number_of_variants = range(1, len(input_data) + 1)
    for variant, sentence, index, result in zip(number_of_variants, input_data, index_data, result_data):
        with self.subTest(f'variation #{variant}', sentence=sentence, index=index, result=result):
            self.assertEqual(adjective_to_verb(sentence, index), result,
                             msg=f'Expected: {result} but got a different word instead.')