1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.lang3.builder;
19
20 import static org.junit.jupiter.api.Assertions.assertNotNull;
21
22 import java.util.ArrayList;
23 import java.util.HashMap;
24 import java.util.List;
25 import java.util.Map;
26
27 import org.junit.jupiter.api.Test;
28
29 /**
30 * Tests {@code ToStringStyle} collection toString can overflow the stack.
31 *
32 * Pre-patch: appendDetail(StringBuffer, String, Collection) calls buffer.append(coll) which invokes the collection's own toString(), bypassing the cycle
33 * registry. Two mutually-referencing ArrayLists cause StackOverflowError. Post-patch: the cycle is detected and a safe representation is produced.
34 */
35 class ToStringBuilderAppendCycleTest {
36
37 @Test
38 void testMutuallyCyclicCollection() {
39 final List<Object> a = new ArrayList<>();
40 final List<Object> b = new ArrayList<>();
41 a.add(b);
42 b.add(a);
43 assertNotNull(new ToStringBuilder(new Object(), ToStringStyle.DEFAULT_STYLE).append("field", a).build());
44 }
45
46 @Test
47 void testMutuallyCyclicMap() {
48 final Map<Object, Object> a = new HashMap<>();
49 final Map<Object, Object> b = new HashMap<>();
50 a.put(b, b);
51 b.put(a, a);
52 assertNotNull(new ToStringBuilder(new Object(), ToStringStyle.DEFAULT_STYLE).append("field", a).build());
53 }
54
55 @Test
56 void testSelfReferentialCollection() {
57 final List<Object> a = new ArrayList<>();
58 a.add(a);
59 assertNotNull(new ToStringBuilder(new Object(), ToStringStyle.DEFAULT_STYLE).append("field", a).build());
60 }
61
62 @Test
63 void testSelfReferentialObjectArray() {
64 final Object[] a = { null };
65 a[0] = a;
66 assertNotNull(new ToStringBuilder(new Object(), ToStringStyle.DEFAULT_STYLE).append("field", a).build());
67 }
68 }