old_contents: import unittest
  import distarray as da
  from distarray.mpi.mpibase import create_comm_of_size, InvalidCommSizeError
  
  
  class TestDistributedArrayProtocol(unittest.TestCase):
  
      def setUp(self):
          try:
              comm = create_comm_of_size(4)
          except InvalidCommSizeError:
              raise unittest.SkipTest('Must run with comm size > 4.')
          else:
              self.arr = da.LocalArray((16,16),
                                       grid_shape=(4,),
                                       comm=comm, buf=None, offset=0)
  
      def test_export(self):
          self.assertIsInstance(self.arr, da.LocalArray)
  
  
  if __name__ == '__main__':
      try:
          unittest.main()
      except SystemExit:
          pass
  
new_contents: import unittest
  import distarray as da
  from distarray.mpi.mpibase import create_comm_of_size, InvalidCommSizeError
  
  
  class TestDistributedArrayProtocol(unittest.TestCase):
  
      def setUp(self):
          try:
              comm = create_comm_of_size(4)
          except InvalidCommSizeError:
              raise unittest.SkipTest('Must run with comm size > 4.')
          else:
              self.arr = da.LocalArray((16,16),
                                       grid_shape=(4,),
                                       comm=comm, buf=None, offset=0)
  
      def test_has_export(self):
          self.assertTrue(hasattr(self.arr, '__distarray__'))
  
      def test_well_formedness(self):
          required_keys = set(("buffer", "dimdata"))
          export = self.arr.__distarray__()
          exported_keys = set(export.keys())
          self.assertEqual(required_keys, exported_keys)
  
  
  if __name__ == '__main__':
      try:
          unittest.main()
      except SystemExit:
          pass
  
subject: Improve basic checks of distarray export.