private void testOverlapCommon(final TableName tn) throws Exception {
    Table t = TEST_UTIL.createMultiRegionTable(tn, HConstants.CATALOG_FAMILY);
    TEST_UTIL.loadTable(t, HConstants.CATALOG_FAMILY);
    List<RegionInfo> ris = MetaTableAccessor.getTableRegions(TEST_UTIL.getConnection(), tn);
    assertTrue(ris.size() > 5);
    HMaster services = TEST_UTIL.getHBaseCluster().getMaster();
    services.getCatalogJanitor().scan();
    CatalogJanitorReport report = services.getCatalogJanitor().getLastReport();
    assertTrue(report.isEmpty());
    // Make a simple overlap spanning second and third region.
    makeOverlap(services, ris.get(1), ris.get(3));
    makeOverlap(services, ris.get(2), ris.get(3));
    makeOverlap(services, ris.get(2), ris.get(4));
  }
Just make sure running fixMeta does right thing for the case of a single-region Table where the
region gets dropped. There is nothing much we can do. We can't restore what we don't know about
(at least from a read of hbase:meta).
hbase-server/src/test/java/org/apache/hadoop/hbase/master/janitor/TestMetaFixer.java