private static void waitForTableRegionCount(final TableName tableName,
    Matcher<? super Integer> matcher) {
    TEST_UTIL.waitFor(TimeUnit.MINUTES.toMillis(5),
      new MatcherPredicate<>("region count for table " + tableName + " does not match expected",
        () -> getRegionCountUnchecked(tableName), matcher));
  }
A test for when a region is the target of both a split and a merge plan. Does not define
expected behavior, only that some change is applied to the table.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/normalizer/TestSimpleRegionNormalizerOnCluster.java