def METHOD_NAME(self, process_mock, send_smtp_mock):
    """The process_email command should accept messages with invalid encoding when using a file input"""
    invalid_characters = b'\xfe\xff'
    with name_of_file_containing(invalid_characters, mode='wb') as filename:
        call_command('process_email', email_file=filename)
    self.assertFalse(send_smtp_mock.called)  # should not send an error email
    self.assertTrue(process_mock.called)
    (msg,) = process_mock.call_args.args
    self.assertEqual(msg, invalid_characters, 'Invalid unicode should be passed to process_email()')