@Test
    public void testIdUserSelection() {
        VisitorParameters params = createVisitorParameters("id.user=1234");
        String expected = "CreateVisitorMessage(buckets=[\n" +
                new BucketId(32, 1234) + "\n" +
                "BucketId(0x0000000000000000)\n" +
                "]\n" +
                "selection='id.user=1234'\n)";
        doTestSingleBucketVisit(params, expected);
    }
Test that using an id.user=foo selection only tries to visit a single
superbucket for that user.
documentapi/src/test/java/com/yahoo/documentapi/messagebus/MessageBusVisitorSessionTestCase.java