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23 
24 /*
25  * @test
26  * @bug 8148174
27  * @summary brittle white box test of internal array management
28  * @run testng ArrayManagement
29  */
30 
31 package test.java.util.Vector;
32 
33 import java.lang.reflect.Field;
34 import java.util.AbstractList;
35 import java.util.Vector;
36 import java.util.Collections;
37 import java.util.List;
38 import java.util.SplittableRandom;
39 
40 import org.testng.annotations.Test;
41 import static org.testng.Assert.*;
42 
43 public class ArrayManagement {
44 
45     /**
46      * A Vector that exposes all protected elements, and checks class
47      * invariants.
48      */
49     static class PublicVector<E> extends Vector<E> {
PublicVector()50         public PublicVector() { super(); }
PublicVector(int capacity)51         public PublicVector(int capacity) { super(capacity); }
PublicVector(int capacity, int capacityIncrement)52         public PublicVector(int capacity, int capacityIncrement) {
53             super(capacity, capacityIncrement);
54         }
elementData()55         public Object[] elementData()  { return elementData; }
modCount()56         public int modCount()          { return modCount; }
capacityIncrement()57         public int capacityIncrement() { return capacityIncrement; }
capacity()58         public int capacity()          { return elementData.length; }
59 
ensureCapacity(int minCapacity)60         public void ensureCapacity(int minCapacity) {
61             int oldCapacity = capacity();
62             int oldModCount = modCount();
63             super.ensureCapacity(minCapacity);
64             assertTrue(capacity() >= minCapacity);
65             if (minCapacity <= oldCapacity)
66                 assertEquals(capacity(), oldCapacity);
67             if (minCapacity > 0)
68                 assertEquals(modCount(), oldModCount + 1);
69         }
70     }
71 
72     static final int DEFAULT_CAPACITY = 10;
73     static final SplittableRandom rnd = new SplittableRandom();
74 
newCapacity(int oldCapacity)75     static int newCapacity(int oldCapacity) {
76         return 2 * oldCapacity;
77     }
78 
singletonList()79     static List<Object> singletonList() {
80         return Collections.singletonList(Boolean.TRUE);
81     }
82 
83     /** Opportunistically randomly test various add operations. */
addOneElement(PublicVector<Object> list)84     static void addOneElement(PublicVector<Object> list) {
85         int size = list.size();
86         int modCount = list.modCount();
87         switch (rnd.nextInt(4)) {
88         case 0: assertTrue(list.add(Boolean.TRUE)); break;
89         case 1: list.add(size, Boolean.TRUE); break;
90         case 2: assertTrue(list.addAll(singletonList())); break;
91         case 3: assertTrue(list.addAll(size, singletonList())); break;
92         default: throw new AssertionError();
93         }
94         assertEquals(list.modCount(), modCount + 1);
95         assertEquals(list.size(), size + 1);
96     }
97 
defaultCapacity()98     @Test public void defaultCapacity() {
99         PublicVector<Object> list = new PublicVector<>();
100         assertEquals(new PublicVector<Object>().capacity(), DEFAULT_CAPACITY);
101         for (int i = 0; i < DEFAULT_CAPACITY; i++) {
102             addOneElement(list);
103             assertEquals(list.capacity(), DEFAULT_CAPACITY);
104         }
105         addOneElement(list);
106         assertEquals(list.capacity(), newCapacity(DEFAULT_CAPACITY));
107     }
108 
defaultCapacityEnsureCapacity()109     @Test public void defaultCapacityEnsureCapacity() {
110         PublicVector<Object> list = new PublicVector<>();
111         for (int i = 0; i <= DEFAULT_CAPACITY; i++) {
112             list.ensureCapacity(i);     // no-op!
113             assertEquals(list.capacity(), DEFAULT_CAPACITY);
114         }
115         for (int i = 0; i < DEFAULT_CAPACITY; i++) {
116             addOneElement(list);
117             assertEquals(list.capacity(), DEFAULT_CAPACITY);
118         }
119         addOneElement(list);
120         assertEquals(list.capacity(), newCapacity(DEFAULT_CAPACITY));
121         {
122             int capacity = list.capacity();
123             list.ensureCapacity(capacity + 1);
124             assertEquals(list.capacity(), newCapacity(capacity));
125         }
126         {
127             int capacity = list.capacity();
128             list.ensureCapacity(3 * capacity);
129             assertEquals(list.capacity(), 3 * capacity);
130         }
131     }
132 
ensureCapacityBeyondDefaultCapacity()133     @Test public void ensureCapacityBeyondDefaultCapacity() {
134         PublicVector<Object> list = new PublicVector<>();
135         list.ensureCapacity(DEFAULT_CAPACITY + 1);
136         assertEquals(list.capacity(), newCapacity(DEFAULT_CAPACITY));
137     }
138 
explicitZeroCapacity()139     @Test public void explicitZeroCapacity() {
140         PublicVector<Object> list = new PublicVector<>(0);
141         assertEquals(list.capacity(), 0);
142         addOneElement(list);
143         assertEquals(list.capacity(), 1);
144         addOneElement(list);
145         assertEquals(list.capacity(), 2);
146         addOneElement(list);
147         assertEquals(list.capacity(), 4);
148         addOneElement(list);
149         assertEquals(list.capacity(), 4);
150         addOneElement(list);
151         assertEquals(list.capacity(), 8);
152         addOneElement(list);
153         assertEquals(list.capacity(), 8);
154         addOneElement(list);
155         assertEquals(list.capacity(), 8);
156         list.clear();
157         assertEquals(list.capacity(), 8);
158     }
159 
explicitZeroCapacityWithCapacityIncrement()160     @Test public void explicitZeroCapacityWithCapacityIncrement() {
161         PublicVector<Object> list = new PublicVector<>(0, 2);
162         assertEquals(list.capacity(), 0);
163         addOneElement(list);
164         assertEquals(list.capacity(), 2);
165         addOneElement(list);
166         assertEquals(list.capacity(), 2);
167         addOneElement(list);
168         assertEquals(list.capacity(), 4);
169         addOneElement(list);
170         assertEquals(list.capacity(), 4);
171         addOneElement(list);
172         assertEquals(list.capacity(), 6);
173         addOneElement(list);
174         assertEquals(list.capacity(), 6);
175         addOneElement(list);
176         assertEquals(list.capacity(), 8);
177         list.clear();
178         assertEquals(list.capacity(), 8);
179     }
180 
explicitLargeCapacity()181     @Test public void explicitLargeCapacity() {
182         int n = DEFAULT_CAPACITY * 3;
183         PublicVector<Object> list = new PublicVector<>(n);
184         assertEquals(list.capacity(), n);
185         list.ensureCapacity(0);
186         list.ensureCapacity(n);
187         for (int i = 0; i < n; i++) addOneElement(list);
188         assertEquals(list.capacity(), n);
189 
190         addOneElement(list);
191         assertEquals(list.capacity(), newCapacity(n));
192     }
193 
explicitLargeCapacityWithCapacityIncrement()194     @Test public void explicitLargeCapacityWithCapacityIncrement() {
195         int n = DEFAULT_CAPACITY * 3;
196         PublicVector<Object> list = new PublicVector<>(n, 2);
197         assertEquals(list.capacity(), n);
198         list.ensureCapacity(0);
199         list.ensureCapacity(n);
200         for (int i = 0; i < n; i++) addOneElement(list);
201         assertEquals(list.capacity(), n);
202 
203         addOneElement(list);
204         assertEquals(list.capacity(), n + 2);
205     }
206 
emptyArraysAreNotShared()207     @Test public void emptyArraysAreNotShared() {
208         assertNotSame(new PublicVector<Object>(0).elementData(),
209                       new PublicVector<Object>(0).elementData());
210     }
211 
negativeCapacity()212     @Test public void negativeCapacity() {
213         for (int capacity : new int[] { -1, Integer.MIN_VALUE }) {
214             try {
215                 new Vector<Object>(capacity);
216                 fail("should throw");
217             } catch (IllegalArgumentException success) {}
218         }
219     }
220 }
221