code: def test_get_sorted_source_vocab_fnames():
      expected_fnames = [C.VOCAB_SRC_NAME % i for i in [1, 2, 10]]
      with mock.patch("os.listdir") as mocked_listdir:
          mocked_listdir.return_value = [
              C.VOCAB_SRC_NAME % i for i in [2, 1, 10]
          ]
          fnames = _get_sorted_source_vocab_fnames(None)
          assert fnames == expected_fnames
  
file_path: sockeye/test/unit/test_vocab.py
imports: import pytest
  from unittest import mock
  from collections import Counter
  import sockeye.constants
  from sockeye.vocab import build_vocab, get_ordered_tokens_from_vocab, is_valid_vocab, _get_sorted_source_vocab_fnames, count_tokens
label_desc: Use image node_id 7 for calling a global function with example usage: test_get_sorted_source_vocab_fnames() without return types