new_contents: import unittest
  
  
  try:
      import pytest  # NOQA
      _error = None
  except ImportError as e:
      _error = e
  
  
  if _error is None:
      from chainer.testing._distribution_test import distribution_unittest
  else:
      class distribution_unittest(unittest.TestCase):
          def test_dummy(self):
              raise RuntimeError('''\
  {} is not available.
  
  Reason: {}: {}'''.format(__name__, type(_error).__name__, _error))
  
subject: Allow `import chainer.testing` without pytest