test/tck/CopyOnWriteArraySetTest.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 * Other contributors include Andrew Wright, Jeffrey Hayes,
 * Pat Fisher, Mike Judd.
 */

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;

import junit.framework.Test;

public class CopyOnWriteArraySetTest extends JSR166TestCase {
    public static void main(String[] args) {
        main(suite(), args);
    }
    public static Test suite() {
        class Implementation implements CollectionImplementation {
            public Class<?> klazz() { return CopyOnWriteArraySet.class; }
            public Set emptyCollection() { return new CopyOnWriteArraySet(); }
            public Object makeElement(int i) { return JSR166TestCase.itemFor(i); }
            public boolean isConcurrent() { return true; }
            public boolean permitsNulls() { return true; }
        }
        return newTestSuite(
                CopyOnWriteArraySetTest.class,
                CollectionTest.testSuite(new Implementation()));
    }

    static CopyOnWriteArraySet<Item> populatedSet(int n) {
        CopyOnWriteArraySet<Item> a = new CopyOnWriteArraySet<>();
        assertTrue(a.isEmpty());
        for (int i = 0; i < n; i++)
            mustAdd(a, i);
        mustEqual(n == 0, a.isEmpty());
        mustEqual(n, a.size());
        return a;
    }

    static CopyOnWriteArraySet<Item> populatedSet(Item[] elements) {
        CopyOnWriteArraySet<Item> a = new CopyOnWriteArraySet<>();
        assertTrue(a.isEmpty());
        for (int i = 0; i < elements.length; i++)
            mustAdd(a, elements[i]);
        assertFalse(a.isEmpty());
        mustEqual(elements.length, a.size());
        return a;
    }

    /**
     * Default-constructed set is empty
     */
    public void testConstructor() {
        CopyOnWriteArraySet<Item> a = new CopyOnWriteArraySet<>();
        assertTrue(a.isEmpty());
    }

    /**
     * Collection-constructed set holds all of its elements
     */
    public void testConstructor3() {
        Item[] items = defaultItems;
        CopyOnWriteArraySet<Item> a = new CopyOnWriteArraySet<>(Arrays.asList(items));
        for (int i = 0; i < SIZE; ++i)
            mustContain(a, i);
    }

    /**
     * addAll adds each non-duplicate element from the given collection
     */
    public void testAddAll() {
        Set<Item> full = populatedSet(3);
        assertTrue(full.addAll(Arrays.asList(three, four, five)));
        mustEqual(6, full.size());
        assertFalse(full.addAll(Arrays.asList(three, four, five)));
        mustEqual(6, full.size());
    }

    /**
     * addAll adds each non-duplicate element from the given collection
     */
    public void testAddAll2() {
        Set<Item> full = populatedSet(3);
        // "one" is duplicate and will not be added
        assertTrue(full.addAll(Arrays.asList(three, four, one)));
        mustEqual(5, full.size());
        assertFalse(full.addAll(Arrays.asList(three, four, one)));
        mustEqual(5, full.size());
    }

    /**
     * add will not add the element if it already exists in the set
     */
    public void testAdd2() {
        Set<Item> full = populatedSet(3);
        full.add(one);
        mustEqual(3, full.size());
    }

    /**
     * add adds the element when it does not exist in the set
     */
    public void testAdd3() {
        Set<Item> full = populatedSet(3);
        full.add(three);
        mustContain(full, three);
    }

    /**
     * clear removes all elements from the set
     */
    public void testClear() {
        Collection<Item> full = populatedSet(3);
        full.clear();
        mustEqual(0, full.size());
        assertTrue(full.isEmpty());
    }

    /**
     * contains returns true for added elements
     */
    public void testContains() {
        Collection<Item> full = populatedSet(3);
        mustContain(full, one);
        mustNotContain(full, five);
    }

    /**
     * Sets with equal elements are equal
     */
    public void testEquals() {
        CopyOnWriteArraySet<Item> a = populatedSet(3);
        CopyOnWriteArraySet<Item> b = populatedSet(3);
        assertTrue(a.equals(b));
        assertTrue(b.equals(a));
        assertTrue(a.containsAll(b));
        assertTrue(b.containsAll(a));
        mustEqual(a.hashCode(), b.hashCode());
        mustEqual(a.size(), b.size());

        a.add(minusOne);
        assertFalse(a.equals(b));
        assertFalse(b.equals(a));
        assertTrue(a.containsAll(b));
        assertFalse(b.containsAll(a));
        b.add(minusOne);
        assertTrue(a.equals(b));
        assertTrue(b.equals(a));
        assertTrue(a.containsAll(b));
        assertTrue(b.containsAll(a));
        mustEqual(a.hashCode(), b.hashCode());

        Item x = a.iterator().next();
        a.remove(x);
        assertFalse(a.equals(b));
        assertFalse(b.equals(a));
        assertFalse(a.containsAll(b));
        assertTrue(b.containsAll(a));
        a.add(x);
        assertTrue(a.equals(b));
        assertTrue(b.equals(a));
        assertTrue(a.containsAll(b));
        assertTrue(b.containsAll(a));
        mustEqual(a.hashCode(), b.hashCode());
        mustEqual(a.size(), b.size());

        CopyOnWriteArraySet<Item> empty1 = new CopyOnWriteArraySet<>(Arrays.asList());
        CopyOnWriteArraySet<Item> empty2 = new CopyOnWriteArraySet<>(Arrays.asList());
        assertTrue(empty1.equals(empty1));
        assertTrue(empty1.equals(empty2));

        assertFalse(empty1.equals(a));
        assertFalse(a.equals(empty1));

        assertFalse(a.equals(null));
    }

    /**
     * containsAll returns true for collections with subset of elements
     */
    public void testContainsAll() {
        Collection<Item> full = populatedSet(3);
        assertTrue(full.containsAll(full));
        assertTrue(full.containsAll(Arrays.asList()));
        assertTrue(full.containsAll(Arrays.asList(one)));
        assertTrue(full.containsAll(Arrays.asList(one, two)));
        assertFalse(full.containsAll(Arrays.asList(one, two, six)));
        assertFalse(full.containsAll(Arrays.asList(six)));

        CopyOnWriteArraySet<Item> empty1 = new CopyOnWriteArraySet<>(Arrays.asList());
        CopyOnWriteArraySet<Item> empty2 = new CopyOnWriteArraySet<>(Arrays.asList());
        assertTrue(empty1.containsAll(empty2));
        assertTrue(empty1.containsAll(empty1));
        assertFalse(empty1.containsAll(full));
        assertTrue(full.containsAll(empty1));

        try {
            full.containsAll(null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * isEmpty is true when empty, else false
     */
    public void testIsEmpty() {
        assertTrue(populatedSet(0).isEmpty());
        assertFalse(populatedSet(3).isEmpty());
    }

    /**
     * iterator() returns an iterator containing the elements of the
     * set in insertion order
     */
    public void testIterator() {
        Collection<Item> empty = new CopyOnWriteArraySet<>();
        assertFalse(empty.iterator().hasNext());
        try {
            empty.iterator().next();
            shouldThrow();
        } catch (NoSuchElementException success) {}

        Item[] elements = seqItems(SIZE);
        shuffle(elements);
        Collection<Item> full = populatedSet(elements);

        Iterator<? extends Item> it = full.iterator();
        for (int j = 0; j < SIZE; j++) {
            assertTrue(it.hasNext());
            mustEqual(elements[j], it.next());
        }
        assertIteratorExhausted(it);
    }

    /**
     * iterator of empty collection has no elements
     */
    public void testEmptyIterator() {
        assertIteratorExhausted(new CopyOnWriteArraySet<Item>().iterator());
    }

    /**
     * iterator remove is unsupported
     */
    public void testIteratorRemove() {
        Collection<Item> full = populatedSet(3);
        Iterator<? extends Item> it = full.iterator();
        it.next();
        try {
            it.remove();
            shouldThrow();
        } catch (UnsupportedOperationException success) {}
    }

    /**
     * toString holds toString of elements
     */
    public void testToString() {
        mustEqual("[]", new CopyOnWriteArraySet<Item>().toString());
        Collection<Item> full = populatedSet(3);
        String s = full.toString();
        for (int i = 0; i < 3; ++i)
            assertTrue(s.contains(String.valueOf(i)));
        mustEqual(new ArrayList<Item>(full).toString(),
                     full.toString());
    }

    /**
     * removeAll removes all elements from the given collection
     */
    public void testRemoveAll() {
        Set<Item> full = populatedSet(3);
        assertTrue(full.removeAll(Arrays.asList(one, two)));
        mustEqual(1, full.size());
        assertFalse(full.removeAll(Arrays.asList(one, two)));
        mustEqual(1, full.size());
    }

    /**
     * remove removes an element
     */
    public void testRemove() {
        Collection<Item> full = populatedSet(3);
        full.remove(one);
        mustNotContain(full, one);
        mustEqual(2, full.size());
    }

    /**
     * size returns the number of elements
     */
    public void testSize() {
        Collection<Item> empty = new CopyOnWriteArraySet<>();
        Collection<Item> full = populatedSet(3);
        mustEqual(3, full.size());
        mustEqual(0, empty.size());
    }

    /**
     * toArray() returns an Object array containing all elements from
     * the set in insertion order
     */
    public void testToArray() {
        Object[] a = new CopyOnWriteArraySet<>().toArray();
        assertTrue(Arrays.equals(new Object[0], a));
        assertSame(Object[].class, a.getClass());

        Item[] elements = seqItems(SIZE);
        shuffle(elements);
        Collection<Item> full = populatedSet(elements);

        assertTrue(Arrays.equals(elements, full.toArray()));
        assertSame(Object[].class, full.toArray().getClass());
    }

    /**
     * toArray(Item array) returns an Item array containing all
     * elements from the set in insertion order
     */
    public void testToArray2() {
        Collection<Item> empty = new CopyOnWriteArraySet<>();
        Item[] a;

        a = new Item[0];
        assertSame(a, empty.toArray(a));

        a = new Item[SIZE / 2];
        Arrays.fill(a, fortytwo);
        assertSame(a, empty.toArray(a));
        assertNull(a[0]);
        for (int i = 1; i < a.length; i++)
            mustEqual(42, a[i]);

        Item[] elements = seqItems(SIZE);
        shuffle(elements);
        Collection<Item> full = populatedSet(elements);

        Arrays.fill(a, fortytwo);
        assertTrue(Arrays.equals(elements, full.toArray(a)));
        for (int i = 0; i < a.length; i++)
            mustEqual(42, a[i]);
        assertSame(Item[].class, full.toArray(a).getClass());

        a = new Item[SIZE];
        Arrays.fill(a, fortytwo);
        assertSame(a, full.toArray(a));
        assertTrue(Arrays.equals(elements, a));

        a = new Item[2 * SIZE];
        Arrays.fill(a, fortytwo);
        assertSame(a, full.toArray(a));
        assertTrue(Arrays.equals(elements, Arrays.copyOf(a, SIZE)));
        assertNull(a[SIZE]);
        for (int i = SIZE + 1; i < a.length; i++)
            mustEqual(42, a[i]);
    }

    /**
     * toArray throws an ArrayStoreException when the given array can
     * not store the objects inside the set
     */
    @SuppressWarnings("CollectionToArraySafeParameter")
    public void testToArray_ArrayStoreException() {
        CopyOnWriteArraySet<Item> c = new CopyOnWriteArraySet<>();
        c.add(one);
        c.add(two);
        try {
            c.toArray(new Long[5]);
            shouldThrow();
        } catch (ArrayStoreException success) {}
    }

    /**
     * A deserialized/reserialized set equals original
     */
    public void testSerialization() throws Exception {
        Set<Item> x = populatedSet(SIZE);
        Set<Item> y = serialClone(x);

        assertNotSame(y, x);
        mustEqual(x.size(), y.size());
        mustEqual(x.toString(), y.toString());
        assertTrue(Arrays.equals(x.toArray(), y.toArray()));
        mustEqual(x, y);
        mustEqual(y, x);
    }

    /**
     * addAll is idempotent
     */
    public void testAddAll_idempotent() throws Exception {
        Set<Item> x = populatedSet(SIZE);
        Set<Item> y = new CopyOnWriteArraySet<>(x);
        y.addAll(x);
        mustEqual(x, y);
        mustEqual(y, x);
    }

}
Revision:	1.44
Committed:	Wed Jan 27 02:55:18 2021 UTC (3 years, 3 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.43:	+1 -0 lines
Log Message:	Suppress all new errorprone "errors"
#	Content
1	/*
2	* Written by Doug Lea with assistance from members of JCP JSR-166
3	* Expert Group and released to the public domain, as explained at
4	* http://creativecommons.org/publicdomain/zero/1.0/
5	* Other contributors include Andrew Wright, Jeffrey Hayes,
6	* Pat Fisher, Mike Judd.
7	*/
8
9	import java.util.ArrayList;
10	import java.util.Arrays;
11	import java.util.Collection;
12	import java.util.Iterator;
13	import java.util.NoSuchElementException;
14	import java.util.Set;
15	import java.util.concurrent.CopyOnWriteArraySet;
16
17	import junit.framework.Test;
18
19	public class CopyOnWriteArraySetTest extends JSR166TestCase {
20	public static void main(String[] args) {
21	main(suite(), args);
22	}
23	public static Test suite() {
24	class Implementation implements CollectionImplementation {
25	public Class<?> klazz() { return CopyOnWriteArraySet.class; }
26	public Set emptyCollection() { return new CopyOnWriteArraySet(); }
27	public Object makeElement(int i) { return JSR166TestCase.itemFor(i); }
28	public boolean isConcurrent() { return true; }
29	public boolean permitsNulls() { return true; }
30	}
31	return newTestSuite(
32	CopyOnWriteArraySetTest.class,
33	CollectionTest.testSuite(new Implementation()));
34	}
35
36	static CopyOnWriteArraySet<Item> populatedSet(int n) {
37	CopyOnWriteArraySet<Item> a = new CopyOnWriteArraySet<>();
38	assertTrue(a.isEmpty());
39	for (int i = 0; i < n; i++)
40	mustAdd(a, i);
41	mustEqual(n == 0, a.isEmpty());
42	mustEqual(n, a.size());
43	return a;
44	}
45
46	static CopyOnWriteArraySet<Item> populatedSet(Item[] elements) {
47	CopyOnWriteArraySet<Item> a = new CopyOnWriteArraySet<>();
48	assertTrue(a.isEmpty());
49	for (int i = 0; i < elements.length; i++)
50	mustAdd(a, elements[i]);
51	assertFalse(a.isEmpty());
52	mustEqual(elements.length, a.size());
53	return a;
54	}
55
56	/**
57	* Default-constructed set is empty
58	*/
59	public void testConstructor() {
60	CopyOnWriteArraySet<Item> a = new CopyOnWriteArraySet<>();
61	assertTrue(a.isEmpty());
62	}
63
64	/**
65	* Collection-constructed set holds all of its elements
66	*/
67	public void testConstructor3() {
68	Item[] items = defaultItems;
69	CopyOnWriteArraySet<Item> a = new CopyOnWriteArraySet<>(Arrays.asList(items));
70	for (int i = 0; i < SIZE; ++i)
71	mustContain(a, i);
72	}
73
74	/**
75	* addAll adds each non-duplicate element from the given collection
76	*/
77	public void testAddAll() {
78	Set<Item> full = populatedSet(3);
79	assertTrue(full.addAll(Arrays.asList(three, four, five)));
80	mustEqual(6, full.size());
81	assertFalse(full.addAll(Arrays.asList(three, four, five)));
82	mustEqual(6, full.size());
83	}
84
85	/**
86	* addAll adds each non-duplicate element from the given collection
87	*/
88	public void testAddAll2() {
89	Set<Item> full = populatedSet(3);
90	// "one" is duplicate and will not be added
91	assertTrue(full.addAll(Arrays.asList(three, four, one)));
92	mustEqual(5, full.size());
93	assertFalse(full.addAll(Arrays.asList(three, four, one)));
94	mustEqual(5, full.size());
95	}
96
97	/**
98	* add will not add the element if it already exists in the set
99	*/
100	public void testAdd2() {
101	Set<Item> full = populatedSet(3);
102	full.add(one);
103	mustEqual(3, full.size());
104	}
105
106	/**
107	* add adds the element when it does not exist in the set
108	*/
109	public void testAdd3() {
110	Set<Item> full = populatedSet(3);
111	full.add(three);
112	mustContain(full, three);
113	}
114
115	/**
116	* clear removes all elements from the set
117	*/
118	public void testClear() {
119	Collection<Item> full = populatedSet(3);
120	full.clear();
121	mustEqual(0, full.size());
122	assertTrue(full.isEmpty());
123	}
124
125	/**
126	* contains returns true for added elements
127	*/
128	public void testContains() {
129	Collection<Item> full = populatedSet(3);
130	mustContain(full, one);
131	mustNotContain(full, five);
132	}
133
134	/**
135	* Sets with equal elements are equal
136	*/
137	public void testEquals() {
138	CopyOnWriteArraySet<Item> a = populatedSet(3);
139	CopyOnWriteArraySet<Item> b = populatedSet(3);
140	assertTrue(a.equals(b));
141	assertTrue(b.equals(a));
142	assertTrue(a.containsAll(b));
143	assertTrue(b.containsAll(a));
144	mustEqual(a.hashCode(), b.hashCode());
145	mustEqual(a.size(), b.size());
146
147	a.add(minusOne);
148	assertFalse(a.equals(b));
149	assertFalse(b.equals(a));
150	assertTrue(a.containsAll(b));
151	assertFalse(b.containsAll(a));
152	b.add(minusOne);
153	assertTrue(a.equals(b));
154	assertTrue(b.equals(a));
155	assertTrue(a.containsAll(b));
156	assertTrue(b.containsAll(a));
157	mustEqual(a.hashCode(), b.hashCode());
158
159	Item x = a.iterator().next();
160	a.remove(x);
161	assertFalse(a.equals(b));
162	assertFalse(b.equals(a));
163	assertFalse(a.containsAll(b));
164	assertTrue(b.containsAll(a));
165	a.add(x);
166	assertTrue(a.equals(b));
167	assertTrue(b.equals(a));
168	assertTrue(a.containsAll(b));
169	assertTrue(b.containsAll(a));
170	mustEqual(a.hashCode(), b.hashCode());
171	mustEqual(a.size(), b.size());
172
173	CopyOnWriteArraySet<Item> empty1 = new CopyOnWriteArraySet<>(Arrays.asList());
174	CopyOnWriteArraySet<Item> empty2 = new CopyOnWriteArraySet<>(Arrays.asList());
175	assertTrue(empty1.equals(empty1));
176	assertTrue(empty1.equals(empty2));
177
178	assertFalse(empty1.equals(a));
179	assertFalse(a.equals(empty1));
180
181	assertFalse(a.equals(null));
182	}
183
184	/**
185	* containsAll returns true for collections with subset of elements
186	*/
187	public void testContainsAll() {
188	Collection<Item> full = populatedSet(3);
189	assertTrue(full.containsAll(full));
190	assertTrue(full.containsAll(Arrays.asList()));
191	assertTrue(full.containsAll(Arrays.asList(one)));
192	assertTrue(full.containsAll(Arrays.asList(one, two)));
193	assertFalse(full.containsAll(Arrays.asList(one, two, six)));
194	assertFalse(full.containsAll(Arrays.asList(six)));
195
196	CopyOnWriteArraySet<Item> empty1 = new CopyOnWriteArraySet<>(Arrays.asList());
197	CopyOnWriteArraySet<Item> empty2 = new CopyOnWriteArraySet<>(Arrays.asList());
198	assertTrue(empty1.containsAll(empty2));
199	assertTrue(empty1.containsAll(empty1));
200	assertFalse(empty1.containsAll(full));
201	assertTrue(full.containsAll(empty1));
202
203	try {
204	full.containsAll(null);
205	shouldThrow();
206	} catch (NullPointerException success) {}
207	}
208
209	/**
210	* isEmpty is true when empty, else false
211	*/
212	public void testIsEmpty() {
213	assertTrue(populatedSet(0).isEmpty());
214	assertFalse(populatedSet(3).isEmpty());
215	}
216
217	/**
218	* iterator() returns an iterator containing the elements of the
219	* set in insertion order
220	*/
221	public void testIterator() {
222	Collection<Item> empty = new CopyOnWriteArraySet<>();
223	assertFalse(empty.iterator().hasNext());
224	try {
225	empty.iterator().next();
226	shouldThrow();
227	} catch (NoSuchElementException success) {}
228
229	Item[] elements = seqItems(SIZE);
230	shuffle(elements);
231	Collection<Item> full = populatedSet(elements);
232
233	Iterator<? extends Item> it = full.iterator();
234	for (int j = 0; j < SIZE; j++) {
235	assertTrue(it.hasNext());
236	mustEqual(elements[j], it.next());
237	}
238	assertIteratorExhausted(it);
239	}
240
241	/**
242	* iterator of empty collection has no elements
243	*/
244	public void testEmptyIterator() {
245	assertIteratorExhausted(new CopyOnWriteArraySet<Item>().iterator());
246	}
247
248	/**
249	* iterator remove is unsupported
250	*/
251	public void testIteratorRemove() {
252	Collection<Item> full = populatedSet(3);
253	Iterator<? extends Item> it = full.iterator();
254	it.next();
255	try {
256	it.remove();
257	shouldThrow();
258	} catch (UnsupportedOperationException success) {}
259	}
260
261	/**
262	* toString holds toString of elements
263	*/
264	public void testToString() {
265	mustEqual("[]", new CopyOnWriteArraySet<Item>().toString());
266	Collection<Item> full = populatedSet(3);
267	String s = full.toString();
268	for (int i = 0; i < 3; ++i)
269	assertTrue(s.contains(String.valueOf(i)));
270	mustEqual(new ArrayList<Item>(full).toString(),
271	full.toString());
272	}
273
274	/**
275	* removeAll removes all elements from the given collection
276	*/
277	public void testRemoveAll() {
278	Set<Item> full = populatedSet(3);
279	assertTrue(full.removeAll(Arrays.asList(one, two)));
280	mustEqual(1, full.size());
281	assertFalse(full.removeAll(Arrays.asList(one, two)));
282	mustEqual(1, full.size());
283	}
284
285	/**
286	* remove removes an element
287	*/
288	public void testRemove() {
289	Collection<Item> full = populatedSet(3);
290	full.remove(one);
291	mustNotContain(full, one);
292	mustEqual(2, full.size());
293	}
294
295	/**
296	* size returns the number of elements
297	*/
298	public void testSize() {
299	Collection<Item> empty = new CopyOnWriteArraySet<>();
300	Collection<Item> full = populatedSet(3);
301	mustEqual(3, full.size());
302	mustEqual(0, empty.size());
303	}
304
305	/**
306	* toArray() returns an Object array containing all elements from
307	* the set in insertion order
308	*/
309	public void testToArray() {
310	Object[] a = new CopyOnWriteArraySet<>().toArray();
311	assertTrue(Arrays.equals(new Object[0], a));
312	assertSame(Object[].class, a.getClass());
313
314	Item[] elements = seqItems(SIZE);
315	shuffle(elements);
316	Collection<Item> full = populatedSet(elements);
317
318	assertTrue(Arrays.equals(elements, full.toArray()));
319	assertSame(Object[].class, full.toArray().getClass());
320	}
321
322	/**
323	* toArray(Item array) returns an Item array containing all
324	* elements from the set in insertion order
325	*/
326	public void testToArray2() {
327	Collection<Item> empty = new CopyOnWriteArraySet<>();
328	Item[] a;
329
330	a = new Item[0];
331	assertSame(a, empty.toArray(a));
332
333	a = new Item[SIZE / 2];
334	Arrays.fill(a, fortytwo);
335	assertSame(a, empty.toArray(a));
336	assertNull(a[0]);
337	for (int i = 1; i < a.length; i++)
338	mustEqual(42, a[i]);
339
340	Item[] elements = seqItems(SIZE);
341	shuffle(elements);
342	Collection<Item> full = populatedSet(elements);
343
344	Arrays.fill(a, fortytwo);
345	assertTrue(Arrays.equals(elements, full.toArray(a)));
346	for (int i = 0; i < a.length; i++)
347	mustEqual(42, a[i]);
348	assertSame(Item[].class, full.toArray(a).getClass());
349
350	a = new Item[SIZE];
351	Arrays.fill(a, fortytwo);
352	assertSame(a, full.toArray(a));
353	assertTrue(Arrays.equals(elements, a));
354
355	a = new Item[2 * SIZE];
356	Arrays.fill(a, fortytwo);
357	assertSame(a, full.toArray(a));
358	assertTrue(Arrays.equals(elements, Arrays.copyOf(a, SIZE)));
359	assertNull(a[SIZE]);
360	for (int i = SIZE + 1; i < a.length; i++)
361	mustEqual(42, a[i]);
362	}
363
364	/**
365	* toArray throws an ArrayStoreException when the given array can
366	* not store the objects inside the set
367	*/
368	@SuppressWarnings("CollectionToArraySafeParameter")
369	public void testToArray_ArrayStoreException() {
370	CopyOnWriteArraySet<Item> c = new CopyOnWriteArraySet<>();
371	c.add(one);
372	c.add(two);
373	try {
374	c.toArray(new Long[5]);
375	shouldThrow();
376	} catch (ArrayStoreException success) {}
377	}
378
379	/**
380	* A deserialized/reserialized set equals original
381	*/
382	public void testSerialization() throws Exception {
383	Set<Item> x = populatedSet(SIZE);
384	Set<Item> y = serialClone(x);
385
386	assertNotSame(y, x);
387	mustEqual(x.size(), y.size());
388	mustEqual(x.toString(), y.toString());
389	assertTrue(Arrays.equals(x.toArray(), y.toArray()));
390	mustEqual(x, y);
391	mustEqual(y, x);
392	}
393
394	/**
395	* addAll is idempotent
396	*/
397	public void testAddAll_idempotent() throws Exception {
398	Set<Item> x = populatedSet(SIZE);
399	Set<Item> y = new CopyOnWriteArraySet<>(x);
400	y.addAll(x);
401	mustEqual(x, y);
402	mustEqual(y, x);
403	}
404
405	}