'A configuration that was saved can be loaded from a new service.'

def test_hash_persists_across_restarts(self):

    path = FilePath(self.mktemp())
    service = ConfigurationPersistenceService(reactor, path)
    service.startService()
    self.addCleanup(service.stopService)
    d = service.save(LATEST_TEST_DEPLOYMENT)
    def saved(_):
        original = self.get_hash(service)
        service.stopService()
        service.startService()
        self.assertEqual(self.get_hash(service), original)
    d.addCallback(saved)
    return d
