@Test public void recBuffer03() {

    RecordBuffer rb = make(4,5);
    contains(rb, 2, 4, 6, 8);
    rb.shiftUp(0);
    rb.set(0, r(0));
    contains(rb, 0, 2, 4, 6, 8);
    rb.shiftDown(0);
    contains(rb, 2, 4, 6, 8);
}