def METHOD_NAME(self):
    self.create_whisper_hosts()
    self.addCleanup(self.wipe_whisper_hosts)
    # Test broken whisper file
    f = open(self.worker2, 'rb+')
    f.seek(10)
    f.write(b'Bad Data')
    f.close()
    reader = WhisperReader(self.worker2, 'hosts.worker2.cpu')
    with self.assertRaises(Exception):
        reader.fetch(self.start_ts-5, self.start_ts)