@Test
public void isEmpty() throws Exception {

    ProviderGroup pg = null;
    Assert.assertTrue(ProviderHelper.isEmpty(pg));
    pg = new ProviderGroup("xxx", null);
    Assert.assertTrue(ProviderHelper.isEmpty(pg));
    pg = new ProviderGroup("xxx", new ArrayList<ProviderInfo>());
    Assert.assertTrue(ProviderHelper.isEmpty(pg));
    pg.add(ProviderHelper.toProviderInfo("127.0.0.1:12200"));
    Assert.assertFalse(ProviderHelper.isEmpty(pg));
}