code: def testScatter(self):
      size = self.COMM.Get_size()
      rank = self.COMM.Get_rank()
      for smess in messages + [messages]:
          for root in range(size):
              if rank == root:
                  rmess = self.COMM.scatter([smess] * size, root=root)
              else:
                  rmess = self.COMM.scatter(None, root=root)
              self.assertEqual(rmess, smess)
  
imports: from mpi4py import MPI
  import mpiunittest
  from functools import reduce
label_desc: Use image node_id 4 for calling the BaseTestCCOObj obj's underlying member method code with example usage: obj.testScatter() without return types