test/tck/ConcurrentLinkedQueueTest.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.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;

import junit.framework.Test;

public class ConcurrentLinkedQueueTest extends JSR166TestCase {

    public static void main(String[] args) {
        main(suite(), args);
    }

    public static Test suite() {
        class Implementation implements CollectionImplementation {
            public Class<?> klazz() { return ConcurrentLinkedQueue.class; }
            public Collection emptyCollection() { return new ConcurrentLinkedQueue(); }
            public Object makeElement(int i) { return i; }
            public boolean isConcurrent() { return true; }
            public boolean permitsNulls() { return false; }
        }
        return newTestSuite(ConcurrentLinkedQueueTest.class,
                            CollectionTest.testSuite(new Implementation()));
    }

    /**
     * Returns a new queue of given size containing consecutive
     * Integers 0 ... n - 1.
     */
    private static ConcurrentLinkedQueue<Integer> populatedQueue(int n) {
        ConcurrentLinkedQueue<Integer> q = new ConcurrentLinkedQueue<>();
        assertTrue(q.isEmpty());
        for (int i = 0; i < n; ++i)
            assertTrue(q.offer(new Integer(i)));
        assertFalse(q.isEmpty());
        assertEquals(n, q.size());
        assertEquals((Integer) 0, q.peek());
        return q;
    }

    /**
     * new queue is empty
     */
    public void testConstructor1() {
        assertEquals(0, new ConcurrentLinkedQueue().size());
    }

    /**
     * Initializing from null Collection throws NPE
     */
    public void testConstructor3() {
        try {
            new ConcurrentLinkedQueue((Collection)null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * Initializing from Collection of null elements throws NPE
     */
    public void testConstructor4() {
        try {
            new ConcurrentLinkedQueue(Arrays.asList(new Integer[SIZE]));
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * Initializing from Collection with some null elements throws NPE
     */
    public void testConstructor5() {
        Integer[] ints = new Integer[SIZE];
        for (int i = 0; i < SIZE - 1; ++i)
            ints[i] = new Integer(i);
        try {
            new ConcurrentLinkedQueue(Arrays.asList(ints));
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * Queue contains all elements of collection used to initialize
     */
    public void testConstructor6() {
        Integer[] ints = new Integer[SIZE];
        for (int i = 0; i < SIZE; ++i)
            ints[i] = new Integer(i);
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue(Arrays.asList(ints));
        for (int i = 0; i < SIZE; ++i)
            assertEquals(ints[i], q.poll());
    }

    /**
     * isEmpty is true before add, false after
     */
    public void testEmpty() {
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        assertTrue(q.isEmpty());
        q.add(one);
        assertFalse(q.isEmpty());
        q.add(two);
        q.remove();
        q.remove();
        assertTrue(q.isEmpty());
    }

    /**
     * size changes when elements added and removed
     */
    public void testSize() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(SIZE - i, q.size());
            q.remove();
        }
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.size());
            q.add(new Integer(i));
        }
    }

    /**
     * offer(null) throws NPE
     */
    public void testOfferNull() {
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        try {
            q.offer(null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * add(null) throws NPE
     */
    public void testAddNull() {
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        try {
            q.add(null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * Offer returns true
     */
    public void testOffer() {
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        assertTrue(q.offer(zero));
        assertTrue(q.offer(one));
    }

    /**
     * add returns true
     */
    public void testAdd() {
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.size());
            assertTrue(q.add(new Integer(i)));
        }
    }

    /**
     * addAll(null) throws NullPointerException
     */
    public void testAddAll1() {
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        try {
            q.addAll(null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * addAll(this) throws IllegalArgumentException
     */
    public void testAddAllSelf() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        try {
            q.addAll(q);
            shouldThrow();
        } catch (IllegalArgumentException success) {}
    }

    /**
     * addAll of a collection with null elements throws NullPointerException
     */
    public void testAddAll2() {
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        try {
            q.addAll(Arrays.asList(new Integer[SIZE]));
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * addAll of a collection with any null elements throws NPE after
     * possibly adding some elements
     */
    public void testAddAll3() {
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        Integer[] ints = new Integer[SIZE];
        for (int i = 0; i < SIZE - 1; ++i)
            ints[i] = new Integer(i);
        try {
            q.addAll(Arrays.asList(ints));
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * Queue contains all elements, in traversal order, of successful addAll
     */
    public void testAddAll5() {
        Integer[] empty = new Integer[0];
        Integer[] ints = new Integer[SIZE];
        for (int i = 0; i < SIZE; ++i)
            ints[i] = new Integer(i);
        ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        assertFalse(q.addAll(Arrays.asList(empty)));
        assertTrue(q.addAll(Arrays.asList(ints)));
        for (int i = 0; i < SIZE; ++i)
            assertEquals(ints[i], q.poll());
    }

    /**
     * poll succeeds unless empty
     */
    public void testPoll() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.poll());
        }
        assertNull(q.poll());
    }

    /**
     * peek returns next element, or null if empty
     */
    public void testPeek() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.peek());
            assertEquals(i, q.poll());
            assertTrue(q.peek() == null ||
                       !q.peek().equals(i));
        }
        assertNull(q.peek());
    }

    /**
     * element returns next element, or throws NSEE if empty
     */
    public void testElement() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.element());
            assertEquals(i, q.poll());
        }
        try {
            q.element();
            shouldThrow();
        } catch (NoSuchElementException success) {}
    }

    /**
     * remove removes next element, or throws NSEE if empty
     */
    public void testRemove() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.remove());
        }
        try {
            q.remove();
            shouldThrow();
        } catch (NoSuchElementException success) {}
    }

    /**
     * remove(x) removes x and returns true if present
     */
    public void testRemoveElement() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        for (int i = 1; i < SIZE; i += 2) {
            assertTrue(q.contains(i));
            assertTrue(q.remove(i));
            assertFalse(q.contains(i));
            assertTrue(q.contains(i - 1));
        }
        for (int i = 0; i < SIZE; i += 2) {
            assertTrue(q.contains(i));
            assertTrue(q.remove(i));
            assertFalse(q.contains(i));
            assertFalse(q.remove(i + 1));
            assertFalse(q.contains(i + 1));
        }
        assertTrue(q.isEmpty());
    }

    /**
     * contains(x) reports true when elements added but not yet removed
     */
    public void testContains() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(q.contains(new Integer(i)));
            q.poll();
            assertFalse(q.contains(new Integer(i)));
        }
    }

    /**
     * clear removes all elements
     */
    public void testClear() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        q.clear();
        assertTrue(q.isEmpty());
        assertEquals(0, q.size());
        q.add(one);
        assertFalse(q.isEmpty());
        q.clear();
        assertTrue(q.isEmpty());
    }

    /**
     * containsAll(c) is true when c contains a subset of elements
     */
    public void testContainsAll() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        ConcurrentLinkedQueue p = new ConcurrentLinkedQueue();
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(q.containsAll(p));
            assertFalse(p.containsAll(q));
            p.add(new Integer(i));
        }
        assertTrue(p.containsAll(q));
    }

    /**
     * retainAll(c) retains only those elements of c and reports true if change
     */
    public void testRetainAll() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        ConcurrentLinkedQueue p = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            boolean changed = q.retainAll(p);
            if (i == 0)
                assertFalse(changed);
            else
                assertTrue(changed);

            assertTrue(q.containsAll(p));
            assertEquals(SIZE - i, q.size());
            p.remove();
        }
    }

    /**
     * removeAll(c) removes only those elements of c and reports true if changed
     */
    public void testRemoveAll() {
        for (int i = 1; i < SIZE; ++i) {
            ConcurrentLinkedQueue q = populatedQueue(SIZE);
            ConcurrentLinkedQueue p = populatedQueue(i);
            assertTrue(q.removeAll(p));
            assertEquals(SIZE - i, q.size());
            for (int j = 0; j < i; ++j) {
                Integer x = (Integer)(p.remove());
                assertFalse(q.contains(x));
            }
        }
    }

    /**
     * toArray contains all elements in FIFO order
     */
    public void testToArray() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        Object[] a = q.toArray();
        assertSame(Object[].class, a.getClass());
        for (Object o : a)
            assertSame(o, q.poll());
        assertTrue(q.isEmpty());
    }

    /**
     * toArray(a) contains all elements in FIFO order
     */
    public void testToArray2() {
        ConcurrentLinkedQueue<Integer> q = populatedQueue(SIZE);
        Integer[] ints = new Integer[SIZE];
        Integer[] array = q.toArray(ints);
        assertSame(ints, array);
        for (Integer o : ints)
            assertSame(o, q.poll());
        assertTrue(q.isEmpty());
    }

    /**
     * toArray(null) throws NullPointerException
     */
    public void testToArray_NullArg() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        try {
            q.toArray((Object[])null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * toArray(incompatible array type) throws ArrayStoreException
     */
    public void testToArray1_BadArg() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        try {
            q.toArray(new String[10]);
            shouldThrow();
        } catch (ArrayStoreException success) {}
    }

    /**
     * iterator iterates through all elements
     */
    public void testIterator() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        Iterator it = q.iterator();
        int i;
        for (i = 0; it.hasNext(); i++)
            assertTrue(q.contains(it.next()));
        assertEquals(i, SIZE);
        assertIteratorExhausted(it);
    }

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

    /**
     * iterator ordering is FIFO
     */
    public void testIteratorOrdering() {
        final ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        q.add(one);
        q.add(two);
        q.add(three);

        int k = 0;
        for (Iterator it = q.iterator(); it.hasNext();) {
            assertEquals(++k, it.next());
        }

        assertEquals(3, k);
    }

    /**
     * Modifications do not cause iterators to fail
     */
    public void testWeaklyConsistentIteration() {
        final ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        q.add(one);
        q.add(two);
        q.add(three);

        for (Iterator it = q.iterator(); it.hasNext();) {
            q.remove();
            it.next();
        }

        assertEquals("queue should be empty again", 0, q.size());
    }

    /**
     * iterator.remove removes current element
     */
    public void testIteratorRemove() {
        final ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
        q.add(one);
        q.add(two);
        q.add(three);
        Iterator it = q.iterator();
        it.next();
        it.remove();
        it = q.iterator();
        assertSame(it.next(), two);
        assertSame(it.next(), three);
        assertFalse(it.hasNext());
    }

    /**
     * toString contains toStrings of elements
     */
    public void testToString() {
        ConcurrentLinkedQueue q = populatedQueue(SIZE);
        String s = q.toString();
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(s.contains(String.valueOf(i)));
        }
    }

    /**
     * A deserialized/reserialized queue has same elements in same order
     */
    public void testSerialization() throws Exception {
        Queue x = populatedQueue(SIZE);
        Queue y = serialClone(x);

        assertNotSame(x, y);
        assertEquals(x.size(), y.size());
        assertEquals(x.toString(), y.toString());
        assertTrue(Arrays.equals(x.toArray(), y.toArray()));
        while (!x.isEmpty()) {
            assertFalse(y.isEmpty());
            assertEquals(x.remove(), y.remove());
        }
        assertTrue(y.isEmpty());
    }

    /**
     * remove(null), contains(null) always return false
     */
    public void testNeverContainsNull() {
        Collection<?>[] qs = {
            new ConcurrentLinkedQueue<Object>(),
            populatedQueue(2),
        };

        for (Collection<?> q : qs) {
            assertFalse(q.contains(null));
            assertFalse(q.remove(null));
        }
    }
}
Revision:	1.49
Committed:	Fri Jun 22 00:04:58 2018 UTC (5 years, 10 months ago) by jsr166
Branch:	MAIN
Changes since 1.48:	+1 -1 lines
Log Message:	sync upstream changes
#	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.Arrays;
10	import java.util.Collection;
11	import java.util.Iterator;
12	import java.util.NoSuchElementException;
13	import java.util.Queue;
14	import java.util.concurrent.ConcurrentLinkedQueue;
15
16	import junit.framework.Test;
17
18	public class ConcurrentLinkedQueueTest extends JSR166TestCase {
19
20	public static void main(String[] args) {
21	main(suite(), args);
22	}
23
24	public static Test suite() {
25	class Implementation implements CollectionImplementation {
26	public Class<?> klazz() { return ConcurrentLinkedQueue.class; }
27	public Collection emptyCollection() { return new ConcurrentLinkedQueue(); }
28	public Object makeElement(int i) { return i; }
29	public boolean isConcurrent() { return true; }
30	public boolean permitsNulls() { return false; }
31	}
32	return newTestSuite(ConcurrentLinkedQueueTest.class,
33	CollectionTest.testSuite(new Implementation()));
34	}
35
36	/**
37	* Returns a new queue of given size containing consecutive
38	* Integers 0 ... n - 1.
39	*/
40	private static ConcurrentLinkedQueue<Integer> populatedQueue(int n) {
41	ConcurrentLinkedQueue<Integer> q = new ConcurrentLinkedQueue<>();
42	assertTrue(q.isEmpty());
43	for (int i = 0; i < n; ++i)
44	assertTrue(q.offer(new Integer(i)));
45	assertFalse(q.isEmpty());
46	assertEquals(n, q.size());
47	assertEquals((Integer) 0, q.peek());
48	return q;
49	}
50
51	/**
52	* new queue is empty
53	*/
54	public void testConstructor1() {
55	assertEquals(0, new ConcurrentLinkedQueue().size());
56	}
57
58	/**
59	* Initializing from null Collection throws NPE
60	*/
61	public void testConstructor3() {
62	try {
63	new ConcurrentLinkedQueue((Collection)null);
64	shouldThrow();
65	} catch (NullPointerException success) {}
66	}
67
68	/**
69	* Initializing from Collection of null elements throws NPE
70	*/
71	public void testConstructor4() {
72	try {
73	new ConcurrentLinkedQueue(Arrays.asList(new Integer[SIZE]));
74	shouldThrow();
75	} catch (NullPointerException success) {}
76	}
77
78	/**
79	* Initializing from Collection with some null elements throws NPE
80	*/
81	public void testConstructor5() {
82	Integer[] ints = new Integer[SIZE];
83	for (int i = 0; i < SIZE - 1; ++i)
84	ints[i] = new Integer(i);
85	try {
86	new ConcurrentLinkedQueue(Arrays.asList(ints));
87	shouldThrow();
88	} catch (NullPointerException success) {}
89	}
90
91	/**
92	* Queue contains all elements of collection used to initialize
93	*/
94	public void testConstructor6() {
95	Integer[] ints = new Integer[SIZE];
96	for (int i = 0; i < SIZE; ++i)
97	ints[i] = new Integer(i);
98	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue(Arrays.asList(ints));
99	for (int i = 0; i < SIZE; ++i)
100	assertEquals(ints[i], q.poll());
101	}
102
103	/**
104	* isEmpty is true before add, false after
105	*/
106	public void testEmpty() {
107	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
108	assertTrue(q.isEmpty());
109	q.add(one);
110	assertFalse(q.isEmpty());
111	q.add(two);
112	q.remove();
113	q.remove();
114	assertTrue(q.isEmpty());
115	}
116
117	/**
118	* size changes when elements added and removed
119	*/
120	public void testSize() {
121	ConcurrentLinkedQueue q = populatedQueue(SIZE);
122	for (int i = 0; i < SIZE; ++i) {
123	assertEquals(SIZE - i, q.size());
124	q.remove();
125	}
126	for (int i = 0; i < SIZE; ++i) {
127	assertEquals(i, q.size());
128	q.add(new Integer(i));
129	}
130	}
131
132	/**
133	* offer(null) throws NPE
134	*/
135	public void testOfferNull() {
136	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
137	try {
138	q.offer(null);
139	shouldThrow();
140	} catch (NullPointerException success) {}
141	}
142
143	/**
144	* add(null) throws NPE
145	*/
146	public void testAddNull() {
147	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
148	try {
149	q.add(null);
150	shouldThrow();
151	} catch (NullPointerException success) {}
152	}
153
154	/**
155	* Offer returns true
156	*/
157	public void testOffer() {
158	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
159	assertTrue(q.offer(zero));
160	assertTrue(q.offer(one));
161	}
162
163	/**
164	* add returns true
165	*/
166	public void testAdd() {
167	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
168	for (int i = 0; i < SIZE; ++i) {
169	assertEquals(i, q.size());
170	assertTrue(q.add(new Integer(i)));
171	}
172	}
173
174	/**
175	* addAll(null) throws NullPointerException
176	*/
177	public void testAddAll1() {
178	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
179	try {
180	q.addAll(null);
181	shouldThrow();
182	} catch (NullPointerException success) {}
183	}
184
185	/**
186	* addAll(this) throws IllegalArgumentException
187	*/
188	public void testAddAllSelf() {
189	ConcurrentLinkedQueue q = populatedQueue(SIZE);
190	try {
191	q.addAll(q);
192	shouldThrow();
193	} catch (IllegalArgumentException success) {}
194	}
195
196	/**
197	* addAll of a collection with null elements throws NullPointerException
198	*/
199	public void testAddAll2() {
200	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
201	try {
202	q.addAll(Arrays.asList(new Integer[SIZE]));
203	shouldThrow();
204	} catch (NullPointerException success) {}
205	}
206
207	/**
208	* addAll of a collection with any null elements throws NPE after
209	* possibly adding some elements
210	*/
211	public void testAddAll3() {
212	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
213	Integer[] ints = new Integer[SIZE];
214	for (int i = 0; i < SIZE - 1; ++i)
215	ints[i] = new Integer(i);
216	try {
217	q.addAll(Arrays.asList(ints));
218	shouldThrow();
219	} catch (NullPointerException success) {}
220	}
221
222	/**
223	* Queue contains all elements, in traversal order, of successful addAll
224	*/
225	public void testAddAll5() {
226	Integer[] empty = new Integer[0];
227	Integer[] ints = new Integer[SIZE];
228	for (int i = 0; i < SIZE; ++i)
229	ints[i] = new Integer(i);
230	ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
231	assertFalse(q.addAll(Arrays.asList(empty)));
232	assertTrue(q.addAll(Arrays.asList(ints)));
233	for (int i = 0; i < SIZE; ++i)
234	assertEquals(ints[i], q.poll());
235	}
236
237	/**
238	* poll succeeds unless empty
239	*/
240	public void testPoll() {
241	ConcurrentLinkedQueue q = populatedQueue(SIZE);
242	for (int i = 0; i < SIZE; ++i) {
243	assertEquals(i, q.poll());
244	}
245	assertNull(q.poll());
246	}
247
248	/**
249	* peek returns next element, or null if empty
250	*/
251	public void testPeek() {
252	ConcurrentLinkedQueue q = populatedQueue(SIZE);
253	for (int i = 0; i < SIZE; ++i) {
254	assertEquals(i, q.peek());
255	assertEquals(i, q.poll());
256	assertTrue(q.peek() == null \|\|
257	!q.peek().equals(i));
258	}
259	assertNull(q.peek());
260	}
261
262	/**
263	* element returns next element, or throws NSEE if empty
264	*/
265	public void testElement() {
266	ConcurrentLinkedQueue q = populatedQueue(SIZE);
267	for (int i = 0; i < SIZE; ++i) {
268	assertEquals(i, q.element());
269	assertEquals(i, q.poll());
270	}
271	try {
272	q.element();
273	shouldThrow();
274	} catch (NoSuchElementException success) {}
275	}
276
277	/**
278	* remove removes next element, or throws NSEE if empty
279	*/
280	public void testRemove() {
281	ConcurrentLinkedQueue q = populatedQueue(SIZE);
282	for (int i = 0; i < SIZE; ++i) {
283	assertEquals(i, q.remove());
284	}
285	try {
286	q.remove();
287	shouldThrow();
288	} catch (NoSuchElementException success) {}
289	}
290
291	/**
292	* remove(x) removes x and returns true if present
293	*/
294	public void testRemoveElement() {
295	ConcurrentLinkedQueue q = populatedQueue(SIZE);
296	for (int i = 1; i < SIZE; i += 2) {
297	assertTrue(q.contains(i));
298	assertTrue(q.remove(i));
299	assertFalse(q.contains(i));
300	assertTrue(q.contains(i - 1));
301	}
302	for (int i = 0; i < SIZE; i += 2) {
303	assertTrue(q.contains(i));
304	assertTrue(q.remove(i));
305	assertFalse(q.contains(i));
306	assertFalse(q.remove(i + 1));
307	assertFalse(q.contains(i + 1));
308	}
309	assertTrue(q.isEmpty());
310	}
311
312	/**
313	* contains(x) reports true when elements added but not yet removed
314	*/
315	public void testContains() {
316	ConcurrentLinkedQueue q = populatedQueue(SIZE);
317	for (int i = 0; i < SIZE; ++i) {
318	assertTrue(q.contains(new Integer(i)));
319	q.poll();
320	assertFalse(q.contains(new Integer(i)));
321	}
322	}
323
324	/**
325	* clear removes all elements
326	*/
327	public void testClear() {
328	ConcurrentLinkedQueue q = populatedQueue(SIZE);
329	q.clear();
330	assertTrue(q.isEmpty());
331	assertEquals(0, q.size());
332	q.add(one);
333	assertFalse(q.isEmpty());
334	q.clear();
335	assertTrue(q.isEmpty());
336	}
337
338	/**
339	* containsAll(c) is true when c contains a subset of elements
340	*/
341	public void testContainsAll() {
342	ConcurrentLinkedQueue q = populatedQueue(SIZE);
343	ConcurrentLinkedQueue p = new ConcurrentLinkedQueue();
344	for (int i = 0; i < SIZE; ++i) {
345	assertTrue(q.containsAll(p));
346	assertFalse(p.containsAll(q));
347	p.add(new Integer(i));
348	}
349	assertTrue(p.containsAll(q));
350	}
351
352	/**
353	* retainAll(c) retains only those elements of c and reports true if change
354	*/
355	public void testRetainAll() {
356	ConcurrentLinkedQueue q = populatedQueue(SIZE);
357	ConcurrentLinkedQueue p = populatedQueue(SIZE);
358	for (int i = 0; i < SIZE; ++i) {
359	boolean changed = q.retainAll(p);
360	if (i == 0)
361	assertFalse(changed);
362	else
363	assertTrue(changed);
364
365	assertTrue(q.containsAll(p));
366	assertEquals(SIZE - i, q.size());
367	p.remove();
368	}
369	}
370
371	/**
372	* removeAll(c) removes only those elements of c and reports true if changed
373	*/
374	public void testRemoveAll() {
375	for (int i = 1; i < SIZE; ++i) {
376	ConcurrentLinkedQueue q = populatedQueue(SIZE);
377	ConcurrentLinkedQueue p = populatedQueue(i);
378	assertTrue(q.removeAll(p));
379	assertEquals(SIZE - i, q.size());
380	for (int j = 0; j < i; ++j) {
381	Integer x = (Integer)(p.remove());
382	assertFalse(q.contains(x));
383	}
384	}
385	}
386
387	/**
388	* toArray contains all elements in FIFO order
389	*/
390	public void testToArray() {
391	ConcurrentLinkedQueue q = populatedQueue(SIZE);
392	Object[] a = q.toArray();
393	assertSame(Object[].class, a.getClass());
394	for (Object o : a)
395	assertSame(o, q.poll());
396	assertTrue(q.isEmpty());
397	}
398
399	/**
400	* toArray(a) contains all elements in FIFO order
401	*/
402	public void testToArray2() {
403	ConcurrentLinkedQueue<Integer> q = populatedQueue(SIZE);
404	Integer[] ints = new Integer[SIZE];
405	Integer[] array = q.toArray(ints);
406	assertSame(ints, array);
407	for (Integer o : ints)
408	assertSame(o, q.poll());
409	assertTrue(q.isEmpty());
410	}
411
412	/**
413	* toArray(null) throws NullPointerException
414	*/
415	public void testToArray_NullArg() {
416	ConcurrentLinkedQueue q = populatedQueue(SIZE);
417	try {
418	q.toArray((Object[])null);
419	shouldThrow();
420	} catch (NullPointerException success) {}
421	}
422
423	/**
424	* toArray(incompatible array type) throws ArrayStoreException
425	*/
426	public void testToArray1_BadArg() {
427	ConcurrentLinkedQueue q = populatedQueue(SIZE);
428	try {
429	q.toArray(new String[10]);
430	shouldThrow();
431	} catch (ArrayStoreException success) {}
432	}
433
434	/**
435	* iterator iterates through all elements
436	*/
437	public void testIterator() {
438	ConcurrentLinkedQueue q = populatedQueue(SIZE);
439	Iterator it = q.iterator();
440	int i;
441	for (i = 0; it.hasNext(); i++)
442	assertTrue(q.contains(it.next()));
443	assertEquals(i, SIZE);
444	assertIteratorExhausted(it);
445	}
446
447	/**
448	* iterator of empty collection has no elements
449	*/
450	public void testEmptyIterator() {
451	assertIteratorExhausted(new ConcurrentLinkedQueue().iterator());
452	}
453
454	/**
455	* iterator ordering is FIFO
456	*/
457	public void testIteratorOrdering() {
458	final ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
459	q.add(one);
460	q.add(two);
461	q.add(three);
462
463	int k = 0;
464	for (Iterator it = q.iterator(); it.hasNext();) {
465	assertEquals(++k, it.next());
466	}
467
468	assertEquals(3, k);
469	}
470
471	/**
472	* Modifications do not cause iterators to fail
473	*/
474	public void testWeaklyConsistentIteration() {
475	final ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
476	q.add(one);
477	q.add(two);
478	q.add(three);
479
480	for (Iterator it = q.iterator(); it.hasNext();) {
481	q.remove();
482	it.next();
483	}
484
485	assertEquals("queue should be empty again", 0, q.size());
486	}
487
488	/**
489	* iterator.remove removes current element
490	*/
491	public void testIteratorRemove() {
492	final ConcurrentLinkedQueue q = new ConcurrentLinkedQueue();
493	q.add(one);
494	q.add(two);
495	q.add(three);
496	Iterator it = q.iterator();
497	it.next();
498	it.remove();
499	it = q.iterator();
500	assertSame(it.next(), two);
501	assertSame(it.next(), three);
502	assertFalse(it.hasNext());
503	}
504
505	/**
506	* toString contains toStrings of elements
507	*/
508	public void testToString() {
509	ConcurrentLinkedQueue q = populatedQueue(SIZE);
510	String s = q.toString();
511	for (int i = 0; i < SIZE; ++i) {
512	assertTrue(s.contains(String.valueOf(i)));
513	}
514	}
515
516	/**
517	* A deserialized/reserialized queue has same elements in same order
518	*/
519	public void testSerialization() throws Exception {
520	Queue x = populatedQueue(SIZE);
521	Queue y = serialClone(x);
522
523	assertNotSame(x, y);
524	assertEquals(x.size(), y.size());
525	assertEquals(x.toString(), y.toString());
526	assertTrue(Arrays.equals(x.toArray(), y.toArray()));
527	while (!x.isEmpty()) {
528	assertFalse(y.isEmpty());
529	assertEquals(x.remove(), y.remove());
530	}
531	assertTrue(y.isEmpty());
532	}
533
534	/**
535	* remove(null), contains(null) always return false
536	*/
537	public void testNeverContainsNull() {
538	Collection<?>[] qs = {
539	new ConcurrentLinkedQueue<Object>(),
540	populatedQueue(2),
541	};
542
543	for (Collection<?> q : qs) {
544	assertFalse(q.contains(null));
545	assertFalse(q.remove(null));
546	}
547	}
548	}