docstr: Test PyUnicode_Append()
docstr_tok: ["Test","PyUnicode_Append","(",")"]
code: def test_append(self):
      """Test PyUnicode_Append()"""
      from _testcapi import unicode_append as append
  
      strings = [
          "abc",
          "\xa1\xa2\xa3",
          "\u4f60\u597d\u4e16",
          "\U0001f600\U0001f601\U0001f602",
      ]
      for left in strings:
          left = left[::-1]
          for right in strings:
              expected = left + right
              self.assertEqual(append(left, right), expected)
  
      self.assertRaises(SystemError, append, "abc", b"abc")
      self.assertRaises(SystemError, append, b"abc", "abc")
      self.assertRaises(SystemError, append, b"abc", b"abc")
      self.assertRaises(SystemError, append, "abc", [])
      self.assertRaises(SystemError, append, [], "abc")
      self.assertRaises(SystemError, append, [], [])
      self.assertRaises(SystemError, append, NULL, "abc")
      self.assertRaises(SystemError, append, "abc", NULL)
  
imports: import unittest
  import sys
  from test import support
  from test.support import import_helper
label_desc: Use image node_id 5 for calling the CAPITest obj's underlying member method code with example usage: obj.test_append() without return types