@Test
  public void testMergeTenRegions() throws Exception {
    final TableName tableName = TableName.valueOf(this.name.getMethodName());
    final ProcedureExecutor<MasterProcedureEnv> procExec = getMasterProcedureExecutor();
    UTIL.createMultiRegionTable(tableName, HConstants.CATALOG_FAMILY);
    testMerge(tableName, 10);
  }
This tests ten region merges in one go.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestMergeTableRegionsProcedure.java