@Test(expected = RuntimeException.class)
public void testNoAvailableInstance() throws TException {

    ServerSelector serverSelector = new ServerSelector(
            "appId", Arrays.asList(NO_AVAILABLE_INSTANCE_1, NO_AVAILABLE_INSTANCE_2), "dasClientVersion", "ppdaiClientVersion", "clientAddress"
    );
    serverSelector.execute(REQUEST);
    fail();
}