protected DiffRepository getDiffRepos() {

    return DiffRepository.lookup(RelOptRulesTest.class);

  }



  @Test public void testReduceNestedCaseWhen() {

    HepProgram preProgram = new HepProgramBuilder()

        .build();



    HepProgramBuilder builder = new HepProgramBuilder();

    builder.addRuleClass(ReduceExpressionsRule.class);

    HepPlanner hepPlanner = new HepPlanner(builder.build());

    hepPlanner.addRule(ReduceExpressionsRule.FILTER_INSTANCE);



    final String sql = "select sal
"

            + "from emp
"

            + "where case when (sal = 1000) then
"

            + "(case when sal = 1000 then null else 1 end is null) else
"

            + "(case when sal = 2000 then null else 1 end is null) end is true";

    checkPlanning(tester, preProgram, hepPlanner, sql);

  }