@Test
public void testGetStatisticsForDistinctKeys() {

    SortedKeyStatisticsAttributeIndex<Integer, Car> backingIndex = mockBackingIndex();
    PartialSortedKeyStatisticsAttributeIndex<Integer, Car> index = wrapWithPartialIndex(backingIndex);
    index.getStatisticsForDistinctKeys(noQueryOptions());
    verify(backingIndex, times(1)).getStatisticsForDistinctKeys(noQueryOptions());
}