private void validateMetaDataAfterDestroy() {
    InternalCache cache = getCache();
    Region rootRegion = PartitionedRegionHelper.getPRRoot(cache);

    await().untilAsserted(() -> assertThat(cache.rootRegions()).isEmpty());

    assertEquals(
        "ThePrIdToPR Map size is:" + PartitionedRegion.getPrIdToPR().size() + " instead of 0",
        numberOfRegions, PartitionedRegion.getPrIdToPR().size());

    assertThat(PartitionedRegion.getPrIdToPR()).hasSize(numberOfRegions);

    for (Object regionObject : rootRegion.subregions(false)) {
      Region region = (Region) regionObject;
      assertThat(region.getName()).doesNotContain(PartitionedRegionHelper.BUCKET_REGION_PREFIX);
    }
  }
This test aims to test the destroyRegion functionality.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/PartitionedRegionDestroyDUnitTest.java