public void testListUserStats() throws Exception{
List<UserStat> stats = dao.listUserStats();
assertEquals(2,stats.size());
UserStat s1 = stats.get(0);
UserStat s2 = stats.get(1);
assertEquals("hchen1",s1.getUsername());
assertEquals(3,s1.getNumOfBookmarks());
assertEquals(1,s1.getNumOfTags());
assertEquals("hchen2",s2.getUsername());
assertEquals(1,s2.getNumOfBookmarks());
assertEquals(1,s2.getNumOfTags());
}