code: def test_encode_file(self):
      with open(os_helper.TESTFN, "wb") as fp:
          fp.write(b"a\xffb\n")
      output = self.get_output("-e", os_helper.TESTFN)
      self.assertEqual(output.rstrip(), b"Yf9iCg==")
  
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 3 for calling the TestMain obj's underlying member method code with example usage: obj.test_encode_file() without return types