@Test
  public void testDefaultAlertGroupRemoved() throws Exception {
    Assert.assertEquals(0, dispatchDao.findAllGroups().size());
    installHdfsService();
    Assert.assertEquals(1, dispatchDao.findAllGroups().size());
    cluster.getService("HDFS").delete(new DeleteHostComponentStatusMetaData());
    Assert.assertEquals(0, dispatchDao.findAllGroups().size());
  }
Tests that a default {@link AlertGroupEntity} is removed when a service is
removed.

@throws Exception
ambari-server/src/test/java/org/apache/ambari/server/state/alerts/AlertEventPublisherTest.java