code: def test_setitem(self):
      ds = DataSet({"x": [[1, 2, 3, 4]] * 40, "y": [[5, 6]] * 40})
      ds.add_field("i", list(range(len(ds))))
      assert ds.get_field("i").content == list(range(len(ds)))
      import random
  
      random.shuffle(ds)
      import numpy as np
  
      np.random.shuffle(ds)
      assert ds.get_field("i").content != list(range(len(ds)))
  
      ins1 = ds[1]
      ds[2] = ds[1]
      assert ds[2]["x"] == ins1["x"] and ds[2]["y"] == ins1["y"]
  
imports: import os
  import pytest
  import numpy
  from fastNLP.core.dataset import DataSet, FieldArray, Instance, ApplyResultException
  from fastNLP import logger
label_desc: Use image node_id 6 for calling the TestDataSetMethods obj's underlying member method code with example usage: obj.test_setitem() without return types