private void validateInitialRegion() {
    assertThat(vm0.invoke(() -> cacheRule.getCache().getRegion(REGION_NAME).size()))
        .isEqualTo(ENTRIES_IN_REGION);
    assertThat(vm1.invoke(() -> cacheRule.getCache().getRegion(REGION_NAME).size()))
        .isEqualTo(ENTRIES_IN_REGION);
    assertThat(vm0.invoke(() -> ((PartitionedRegion) (cacheRule.getCache().getRegion(REGION_NAME)))
        .getLocalBucketsListTestOnly().size())).isEqualTo(TOTAL_NUMBER_BUCKETS);
    assertThat(vm1.invoke(() -> ((PartitionedRegion) (cacheRule.getCache().getRegion(REGION_NAME)))
        .getLocalBucketsListTestOnly().size())).isEqualTo(0);
  }
Do validation on the initial region before rebalancing. It is expected that all buckets and
data live on vm0; vm1 does not host any buckets.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/partitioned/BucketRebalanceStatRegressionTest.java