code: def test_decode(self):
      with open(os_helper.TESTFN, "wb") as fp:
          fp.write(b"Yf9iCg==")
      output = self.get_output("-d", os_helper.TESTFN)
      self.assertEqual(output.rstrip(), b"a\xffb")
  
imports: import unittest
  import base64
  import binascii
  import os
  from array import array
  from test.support import os_helper
  from test.support import script_helper
label_desc: Use image node_id 5 for calling the TestMain obj's underlying member method code with example usage: obj.test_decode() without return types