code: def test_replace_at_index(self):
      test_field = CnTextField(sents[0])
      self.assertRaises(
          AssertionError, test_field.replace_at_index, 5, "好的"
      )
      self.assertEqual(
          "我们正在玩好乓球，你真的太懒了。她打的很漂亮。",
          test_field.replace_at_index(5, "好").text,
      )
  
imports: import unittest
  from textflint.input.component.field.cn_text_field import *
label_desc: Use image node_id 17 for calling the TestCnTextField obj's underlying member method code with example usage: obj.test_replace_at_index() without return types