code: @Test public void testHostOs() throws Exception {
    Clusters clusters=mock(Clusters.class);
    ActionQueue queue=mock(ActionQueue.class);
    ActionManager manager=mock(ActionManager.class);
    Injector injector=mock(Injector.class);
    doNothing().when(injector).injectMembers(any());
    HeartBeatHandler handler=new HeartBeatHandler(clusters,queue,manager,injector);
    String os=handler.getOsType("RedHat","6.1");
    Assert.assertEquals("redhat6",os);
    os=handler.getOsType("RedHat","6");
    Assert.assertEquals("redhat6",os);
    os=handler.getOsType("RedHat6","");
    Assert.assertEquals("redhat6",os);
  }
  