@Test
public void testGetRackHostname() {

  String str = "/rack1/node1";
  String rackHostname[] = SLSUtils.getRackHostName(str);
  Assert.assertEquals("rack1", rackHostname[0]);
  Assert.assertEquals("node1", rackHostname[1]);
  str = "/rackA/rackB/node1";
  rackHostname = SLSUtils.getRackHostName(str);
  Assert.assertEquals("rackA/rackB", rackHostname[0]);
  Assert.assertEquals("node1", rackHostname[1]);
}