@Before
  public void setup() throws IOException {
    TESTING_UTIL.ensureSomeNonStoppedRegionServersAvailable(NB_SERVERS);
    this.admin = TESTING_UTIL.getAdmin();
    this.cluster = TESTING_UTIL.getMiniHBaseCluster();
  }
The below tests are testing split region against a running cluster
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestSplitTransactionOnCluster.java