public boolean assignRegion(final RegionInfo regionInfo)
    throws IOException, InterruptedException {
    final AssignmentManager am = getHBaseCluster().getMaster().getAssignmentManager();
    am.assign(regionInfo);
    return AssignmentTestingUtil.waitForAssignment(am, regionInfo);
  }
Uses directly the assignment manager to assign the region. and waits until the specified region
has completed assignment.
@return true if the region is assigned false otherwise.
hbase-testing-util/src/main/java/org/apache/hadoop/hbase/HBaseTestingUtility.java