@Test
  public void testRemoveMapping() throws IMQException {
    addValues(region, numValues);

    IndexRegionTestEntry ire = (IndexRegionTestEntry) entries.remove(8);
    indexDataStructure.removeMapping("" + 8, ire.regionEntry);
    validateIndexStorage();

    ire = (IndexRegionTestEntry) entries.remove(4);
    indexDataStructure.removeMapping("" + 4, ire.regionEntry);
    validateIndexStorage();
  }
this test adds values to the index storage and then removes an entry. It validates the index
storage against the test list and then removes and validates again
geode-core/src/integrationTest/java/org/apache/geode/cache/query/internal/index/MapIndexStoreJUnitTest.java