code: def test_fail_to_make_dir(self):
      with mock.patch("os.makedirs") as f:
          f.side_effect = OSError()
          with self.assertRaises(OSError):
              dataset.cached_download("https://example.com")
  
imports: import os
  import shutil
  import tempfile
  import unittest
  import mock
  from chainer import dataset
  from chainer import testing
label_desc: Use image node_id 3 for calling the TestCachedDownload obj's underlying member method code with example usage: obj.test_fail_to_make_dir() without return types