@Test public void recBuffer04() {

    RecordBuffer rb = make(4,5);
    contains(rb, 2, 4, 6, 8);
    rb.shiftDown(0);
    contains(rb, 4, 6, 8);
    rb.shiftUp(0);
    rb.set(0,r(1));
    contains(rb, 1, 4, 6, 8);
}