@Test
  public void testMapIndexUsableQueryOnEmptyRegion() throws Exception {
    IndexManager.TEST_RANGEINDEX_ONLY = true;
    QueryService qs = CacheUtils.getQueryService();
    LocalRegion testRgn = (LocalRegion) CacheUtils.createRegion("testRgn", null);
    Index i1 =
        qs.createIndex("Index1", IndexType.FUNCTIONAL, "objs.maap['key2','key3']",
            SEPARATOR + "testRgn objs");
    qs = CacheUtils.getQueryService();
    // Execute Queries without Indexes
    Query q = CacheUtils.getQueryService()
        .newQuery(
            "SELECT DISTINCT * FROM " + SEPARATOR + "testRgn itr1  WHERE itr1.maap['key2'] >= 3 ");
    SelectResults sr = (SelectResults) q.execute();
    assertTrue(sr.isEmpty());
  }
Test to check if Region short cut method is used for querying, the Primary key index
utilization occurs or not
geode-core/src/integrationTest/java/org/apache/geode/cache/query/internal/index/IndexUseJUnitTest.java