@Before
    public void setup() throws IOException {
        // Set up a socket listening on an arbitrary port. 
        serverSocket = ServerSocketFactory.getDefault().createServerSocket();
        serverSocket.bind(new InetSocketAddress(0));

        // Point serverURI at the socket.
        try {
            int port = serverSocket.getLocalPort();
            serverURI = new URI("http", null, "localhost", port, "/", null, null);
        } catch (URISyntaxException e) {
            throw new RuntimeException(e);
        }
    }