At the very least we should implement it by calling SearchResult.getHitCount().

If necessary, we can think about a better performing solution that would not fetch hits when we only need the result count. We could take advantage of a new, dedicated SPI such as SearchQuery.executeCount(), we could set the SearchQuery result limit to 0 before executing it in that specific case.

For testing, see org/hibernate/search/v6poc/integrationtest/orm/OrmAnnotationMappingIT.java:398 and org/hibernate/search/v6poc/integrationtest/orm/OrmProgrammaticMappingIT.java:393