private void pingServer(Spec spec) {
        long endTime = System.currentTimeMillis() + 60_000;
        Request req = new Request("ping");
        while (System.currentTimeMillis() < endTime) {
            performRequest(req, spec);
            if (!req.isError() && req.returnValues().size() > 0 && req.returnValues().get(0).asInt32() == 0) {
                break;
            }
            req = new Request("ping");
        }
        assertFalse(req.isError());
        assertTrue(req.returnValues().size() > 0);
        assertEquals(0, req.returnValues().get(0).asInt32());
    }
Tester for running rpc server.

@author Ulf Lilleengen
configserver/src/test/java/com/yahoo/vespa/config/server/rpc/RpcTester.java