Assert.assertEquals(LOFilter.class, next.getClass());
next = plan.getSuccessors(next).get(0);
Assert.assertEquals(LOStore.class, next.getClass());
// run push up filter rule
r = new PushUpFilter("PushUpFilter");
s = new HashSet<Rule>();
s.add(r);
ls = new ArrayList<Set<Rule>>();
ls.add(s);
optimizer = new MyPlanOptimizer(plan, ls, 3);