code: def testAllocate(self):
      buffer = MPI.buffer
      for size in (0, 1, 2):
          buf = buffer.allocate(size)
          self.assertEqual(buf.nbytes, size)
          self.assertNotEqual(buf.address, 0)
          view = memoryview(buf.obj)
          self.assertEqual(buf.nbytes, view.nbytes)
      for clear in (False, True):
          buf = buffer.allocate(1024, clear)
          self.assertEqual(buf.nbytes, 1024)
          self.assertNotEqual(buf.address, 0)
          if clear:
              self.assertEqual(buf[0], 0)
              self.assertEqual(buf[-1], 0)
      self.assertRaises(TypeError, buffer.allocate, None)
      self.assertRaises(ValueError, buffer.allocate, -1)
  
file_path: mpi4py/test/test_buffer.py
imports: from mpi4py import MPI
  import mpiunittest
label_desc: Use image node_id 6 for calling the TestBuffer obj's underlying member method code with example usage: obj.testAllocate() without return types