1/*
2 * Copyright (c) 2023-2024 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16class Residence {
17    numberOfRooms: Int = 1;
18}
19
20class Person {
21    residence: Residence = new Residence();
22}
23
24function dummy(): Person | null {
25    return null;
26}
27
28function main(): void {
29    let john: Person | null = dummy();
30    let test = john?.residence?.numberOfRooms;
31    assert (test == null);
32    let nullsafety_test = john?.residence?.numberOfRooms ?? "unknown";
33    assert (nullsafety_test == "unknown");
34}
35