test/tck/Collection8Test.java

/*
 * Written by Doug Lea and Martin Buchholz 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/
 */

import static java.util.concurrent.TimeUnit.HOURS;
import static java.util.concurrent.TimeUnit.MILLISECONDS;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Queue;
import java.util.Spliterator;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.Phaser;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Collectors;

import junit.framework.Test;

/**
 * Contains tests applicable to all jdk8+ Collection implementations.
 * An extension of CollectionTest.
 */
public class Collection8Test extends JSR166TestCase {
    final CollectionImplementation impl;

    /** Tests are parameterized by a Collection implementation. */
    Collection8Test(CollectionImplementation impl, String methodName) {
        super(methodName);
        this.impl = impl;
    }

    public static Test testSuite(CollectionImplementation impl) {
        return parameterizedTestSuite(Collection8Test.class,
                                      CollectionImplementation.class,
                                      impl);
    }

    Object bomb() {
        return new Object() {
                public boolean equals(Object x) { throw new AssertionError(); }
                public int hashCode() { throw new AssertionError(); }
            };
    }

    /** Checks properties of empty collections. */
    public void testEmptyMeansEmpty() throws Throwable {
        Collection c = impl.emptyCollection();
        emptyMeansEmpty(c);

        if (c instanceof java.io.Serializable) {
            try {
                emptyMeansEmpty(serialClonePossiblyFailing(c));
            } catch (java.io.NotSerializableException ex) {
                // excusable when we have a serializable wrapper around
                // a non-serializable collection, as can happen with:
                // Vector.subList() => wrapped AbstractList$RandomAccessSubList
                if (testImplementationDetails
                    && (! c.getClass().getName().matches(
                                "java.util.Collections.*")))
                    throw ex;
            }
        }

        Collection clone = cloneableClone(c);
        if (clone != null)
            emptyMeansEmpty(clone);
    }

    void emptyMeansEmpty(Collection c) throws InterruptedException {
        assertTrue(c.isEmpty());
        assertEquals(0, c.size());
        assertEquals("[]", c.toString());
        {
            Object[] a = c.toArray();
            assertEquals(0, a.length);
            assertSame(Object[].class, a.getClass());
        }
        {
            Object[] a = new Object[0];
            assertSame(a, c.toArray(a));
        }
        {
            Integer[] a = new Integer[0];
            assertSame(a, c.toArray(a));
        }
        {
            Integer[] a = { 1, 2, 3};
            assertSame(a, c.toArray(a));
            assertNull(a[0]);
            assertSame(2, a[1]);
            assertSame(3, a[2]);
        }
        assertIteratorExhausted(c.iterator());
        Consumer alwaysThrows = e -> { throw new AssertionError(); };
        c.forEach(alwaysThrows);
        c.iterator().forEachRemaining(alwaysThrows);
        c.spliterator().forEachRemaining(alwaysThrows);
        assertFalse(c.spliterator().tryAdvance(alwaysThrows));
        if (c.spliterator().hasCharacteristics(Spliterator.SIZED))
            assertEquals(0, c.spliterator().estimateSize());
        assertFalse(c.contains(bomb()));
        assertFalse(c.remove(bomb()));
        if (c instanceof Queue) {
            Queue q = (Queue) c;
            assertNull(q.peek());
            assertNull(q.poll());
        }
        if (c instanceof Deque) {
            Deque d = (Deque) c;
            assertNull(d.peekFirst());
            assertNull(d.peekLast());
            assertNull(d.pollFirst());
            assertNull(d.pollLast());
            assertIteratorExhausted(d.descendingIterator());
            d.descendingIterator().forEachRemaining(alwaysThrows);
            assertFalse(d.removeFirstOccurrence(bomb()));
            assertFalse(d.removeLastOccurrence(bomb()));
        }
        if (c instanceof BlockingQueue) {
            BlockingQueue q = (BlockingQueue) c;
            assertNull(q.poll(0L, MILLISECONDS));
        }
        if (c instanceof BlockingDeque) {
            BlockingDeque q = (BlockingDeque) c;
            assertNull(q.pollFirst(0L, MILLISECONDS));
            assertNull(q.pollLast(0L, MILLISECONDS));
        }
    }

    public void testNullPointerExceptions() throws InterruptedException {
        Collection c = impl.emptyCollection();
        assertThrows(
            NullPointerException.class,
            () -> c.addAll(null),
            () -> c.containsAll(null),
            () -> c.retainAll(null),
            () -> c.removeAll(null),
            () -> c.removeIf(null),
            () -> c.forEach(null),
            () -> c.iterator().forEachRemaining(null),
            () -> c.spliterator().forEachRemaining(null),
            () -> c.spliterator().tryAdvance(null),
            () -> c.toArray(null));

        if (!impl.permitsNulls()) {
            assertThrows(
                NullPointerException.class,
                () -> c.add(null));
        }
        if (!impl.permitsNulls() && c instanceof Queue) {
            Queue q = (Queue) c;
            assertThrows(
                NullPointerException.class,
                () -> q.offer(null));
        }
        if (!impl.permitsNulls() && c instanceof Deque) {
            Deque d = (Deque) c;
            assertThrows(
                NullPointerException.class,
                () -> d.addFirst(null),
                () -> d.addLast(null),
                () -> d.offerFirst(null),
                () -> d.offerLast(null),
                () -> d.push(null),
                () -> d.descendingIterator().forEachRemaining(null));
        }
        if (c instanceof BlockingQueue) {
            BlockingQueue q = (BlockingQueue) c;
            assertThrows(
                NullPointerException.class,
                () -> {
                    try { q.offer(null, 1L, HOURS); }
                    catch (InterruptedException ex) {
                        throw new AssertionError(ex);
                    }},
                () -> {
                    try { q.put(null); }
                    catch (InterruptedException ex) {
                        throw new AssertionError(ex);
                    }});
        }
        if (c instanceof BlockingDeque) {
            BlockingDeque q = (BlockingDeque) c;
            assertThrows(
                NullPointerException.class,
                () -> {
                    try { q.offerFirst(null, 1L, HOURS); }
                    catch (InterruptedException ex) {
                        throw new AssertionError(ex);
                    }},
                () -> {
                    try { q.offerLast(null, 1L, HOURS); }
                    catch (InterruptedException ex) {
                        throw new AssertionError(ex);
                    }},
                () -> {
                    try { q.putFirst(null); }
                    catch (InterruptedException ex) {
                        throw new AssertionError(ex);
                    }},
                () -> {
                    try { q.putLast(null); }
                    catch (InterruptedException ex) {
                        throw new AssertionError(ex);
                    }});
        }
    }

    public void testNoSuchElementExceptions() {
        Collection c = impl.emptyCollection();
        assertThrows(
            NoSuchElementException.class,
            () -> c.iterator().next());

        if (c instanceof Queue) {
            Queue q = (Queue) c;
            assertThrows(
                NoSuchElementException.class,
                () -> q.element(),
                () -> q.remove());
        }
        if (c instanceof Deque) {
            Deque d = (Deque) c;
            assertThrows(
                NoSuchElementException.class,
                () -> d.getFirst(),
                () -> d.getLast(),
                () -> d.removeFirst(),
                () -> d.removeLast(),
                () -> d.pop(),
                () -> d.descendingIterator().next());
        }
    }

    public void testRemoveIf() {
        Collection c = impl.emptyCollection();
        boolean ordered =
            c.spliterator().hasCharacteristics(Spliterator.ORDERED);
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        int n = rnd.nextInt(6);
        for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
        AtomicReference threwAt = new AtomicReference(null);
        List orig = rnd.nextBoolean()
            ? new ArrayList(c)
            : Arrays.asList(c.toArray());

        // Merely creating an iterator can change ArrayBlockingQueue behavior
        Iterator it = rnd.nextBoolean() ? c.iterator() : null;

        ArrayList survivors = new ArrayList();
        ArrayList accepts = new ArrayList();
        ArrayList rejects = new ArrayList();

        Predicate randomPredicate = e -> {
            assertNull(threwAt.get());
            switch (rnd.nextInt(3)) {
            case 0: accepts.add(e); return true;
            case 1: rejects.add(e); return false;
            case 2: threwAt.set(e); throw new ArithmeticException();
            default: throw new AssertionError();
            }
        };
        try {
            try {
                boolean modified = c.removeIf(randomPredicate);
                assertNull(threwAt.get());
                assertEquals(modified, accepts.size() > 0);
                assertEquals(modified, rejects.size() != n);
                assertEquals(accepts.size() + rejects.size(), n);
                if (ordered) {
                    assertEquals(rejects,
                                 Arrays.asList(c.toArray()));
                } else {
                    assertEquals(new HashSet(rejects),
                                 new HashSet(Arrays.asList(c.toArray())));
                }
            } catch (ArithmeticException ok) {
                assertNotNull(threwAt.get());
                assertTrue(c.contains(threwAt.get()));
            }
            if (it != null && impl.isConcurrent())
                // check for weakly consistent iterator
                while (it.hasNext()) assertTrue(orig.contains(it.next()));
            switch (rnd.nextInt(4)) {
            case 0: survivors.addAll(c); break;
            case 1: survivors.addAll(Arrays.asList(c.toArray())); break;
            case 2: c.forEach(survivors::add); break;
            case 3: for (Object e : c) survivors.add(e); break;
            }
            assertTrue(orig.containsAll(accepts));
            assertTrue(orig.containsAll(rejects));
            assertTrue(orig.containsAll(survivors));
            assertTrue(orig.containsAll(c));
            assertTrue(c.containsAll(rejects));
            assertTrue(c.containsAll(survivors));
            assertTrue(survivors.containsAll(rejects));
            if (threwAt.get() == null) {
                assertEquals(n - accepts.size(), c.size());
                for (Object x : accepts) assertFalse(c.contains(x));
            } else {
                // Two acceptable behaviors: entire removeIf call is one
                // transaction, or each element processed is one transaction.
                assertTrue(n == c.size() || n == c.size() + accepts.size());
                int k = 0;
                for (Object x : accepts) if (c.contains(x)) k++;
                assertTrue(k == accepts.size() || k == 0);
            }
        } catch (Throwable ex) {
            System.err.println(impl.klazz());
            // c is at risk of corruption if we got here, so be lenient
            try { System.err.printf("c=%s%n", c); }
            catch (Throwable t) { t.printStackTrace(); }
            System.err.printf("n=%d%n", n);
            System.err.printf("orig=%s%n", orig);
            System.err.printf("accepts=%s%n", accepts);
            System.err.printf("rejects=%s%n", rejects);
            System.err.printf("survivors=%s%n", survivors);
            System.err.printf("threwAt=%s%n", threwAt.get());
            throw ex;
        }
    }

    /**
     * Various ways of traversing a collection yield same elements
     */
    public void testIteratorEquivalence() {
        Collection c = impl.emptyCollection();
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        int n = rnd.nextInt(6);
        for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
        ArrayList iterated = new ArrayList();
        ArrayList iteratedForEachRemaining = new ArrayList();
        ArrayList tryAdvanced = new ArrayList();
        ArrayList spliterated = new ArrayList();
        ArrayList forEached = new ArrayList();
        ArrayList removeIfed = new ArrayList();
        for (Object x : c) iterated.add(x);
        c.iterator().forEachRemaining(iteratedForEachRemaining::add);
        for (Spliterator s = c.spliterator();
             s.tryAdvance(tryAdvanced::add); ) {}
        c.spliterator().forEachRemaining(spliterated::add);
        c.forEach(forEached::add);
        c.removeIf(e -> { removeIfed.add(e); return false; });
        boolean ordered =
            c.spliterator().hasCharacteristics(Spliterator.ORDERED);
        if (c instanceof List || c instanceof Deque)
            assertTrue(ordered);
        if (ordered) {
            assertEquals(iterated, iteratedForEachRemaining);
            assertEquals(iterated, tryAdvanced);
            assertEquals(iterated, spliterated);
            assertEquals(iterated, forEached);
            assertEquals(iterated, removeIfed);
        } else {
            HashSet cset = new HashSet(c);
            assertEquals(cset, new HashSet(iterated));
            assertEquals(cset, new HashSet(iteratedForEachRemaining));
            assertEquals(cset, new HashSet(tryAdvanced));
            assertEquals(cset, new HashSet(spliterated));
            assertEquals(cset, new HashSet(forEached));
            assertEquals(cset, new HashSet(removeIfed));
        }
        if (c instanceof Deque) {
            Deque d = (Deque) c;
            ArrayList descending = new ArrayList();
            ArrayList descendingForEachRemaining = new ArrayList();
            for (Iterator it = d.descendingIterator(); it.hasNext(); )
                descending.add(it.next());
            d.descendingIterator().forEachRemaining(
                e -> descendingForEachRemaining.add(e));
            Collections.reverse(descending);
            Collections.reverse(descendingForEachRemaining);
            assertEquals(iterated, descending);
            assertEquals(iterated, descendingForEachRemaining);
        }
    }

    /**
     * Calling Iterator#remove() after Iterator#forEachRemaining
     * should (maybe) remove last element
     */
    public void testRemoveAfterForEachRemaining() {
        Collection c = impl.emptyCollection();
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        testCollection: {
            int n = 3 + rnd.nextInt(2);
            for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
            Iterator it = c.iterator();
            assertTrue(it.hasNext());
            assertEquals(impl.makeElement(0), it.next());
            assertTrue(it.hasNext());
            assertEquals(impl.makeElement(1), it.next());
            it.forEachRemaining(e -> assertTrue(c.contains(e)));
            if (testImplementationDetails) {
                if (c instanceof java.util.concurrent.ArrayBlockingQueue) {
                    assertIteratorExhausted(it);
                } else {
                    try { it.remove(); }
                    catch (UnsupportedOperationException ok) {
                        break testCollection;
                    }
                    assertEquals(n - 1, c.size());
                    for (int i = 0; i < n - 1; i++)
                        assertTrue(c.contains(impl.makeElement(i)));
                    assertFalse(c.contains(impl.makeElement(n - 1)));
                }
            }
        }
        if (c instanceof Deque) {
            Deque d = (Deque) impl.emptyCollection();
            int n = 3 + rnd.nextInt(2);
            for (int i = 0; i < n; i++) d.add(impl.makeElement(i));
            Iterator it = d.descendingIterator();
            assertTrue(it.hasNext());
            assertEquals(impl.makeElement(n - 1), it.next());
            assertTrue(it.hasNext());
            assertEquals(impl.makeElement(n - 2), it.next());
            it.forEachRemaining(e -> assertTrue(c.contains(e)));
            if (testImplementationDetails) {
                it.remove();
                assertEquals(n - 1, d.size());
                for (int i = 1; i < n; i++)
                    assertTrue(d.contains(impl.makeElement(i)));
                assertFalse(d.contains(impl.makeElement(0)));
            }
        }
    }

    /**
     * stream().forEach returns elements in the collection
     */
    public void testStreamForEach() throws Throwable {
        final Collection c = impl.emptyCollection();
        final AtomicLong count = new AtomicLong(0L);
        final Object x = impl.makeElement(1);
        final Object y = impl.makeElement(2);
        final ArrayList found = new ArrayList();
        Consumer<Object> spy = o -> found.add(o);
        c.stream().forEach(spy);
        assertTrue(found.isEmpty());

        assertTrue(c.add(x));
        c.stream().forEach(spy);
        assertEquals(Collections.singletonList(x), found);
        found.clear();

        assertTrue(c.add(y));
        c.stream().forEach(spy);
        assertEquals(2, found.size());
        assertTrue(found.contains(x));
        assertTrue(found.contains(y));
        found.clear();

        c.clear();
        c.stream().forEach(spy);
        assertTrue(found.isEmpty());
    }

    public void testStreamForEachConcurrentStressTest() throws Throwable {
        if (!impl.isConcurrent()) return;
        final Collection c = impl.emptyCollection();
        final long testDurationMillis = timeoutMillis();
        final AtomicBoolean done = new AtomicBoolean(false);
        final Object elt = impl.makeElement(1);
        final Future<?> f1, f2;
        final ExecutorService pool = Executors.newCachedThreadPool();
        try (PoolCleaner cleaner = cleaner(pool, done)) {
            final CountDownLatch threadsStarted = new CountDownLatch(2);
            Runnable checkElt = () -> {
                threadsStarted.countDown();
                while (!done.get())
                    c.stream().forEach(x -> assertSame(x, elt)); };
            Runnable addRemove = () -> {
                threadsStarted.countDown();
                while (!done.get()) {
                    assertTrue(c.add(elt));
                    assertTrue(c.remove(elt));
                }};
            f1 = pool.submit(checkElt);
            f2 = pool.submit(addRemove);
            Thread.sleep(testDurationMillis);
        }
        assertNull(f1.get(0L, MILLISECONDS));
        assertNull(f2.get(0L, MILLISECONDS));
    }

    /**
     * collection.forEach returns elements in the collection
     */
    public void testForEach() throws Throwable {
        final Collection c = impl.emptyCollection();
        final AtomicLong count = new AtomicLong(0L);
        final Object x = impl.makeElement(1);
        final Object y = impl.makeElement(2);
        final ArrayList found = new ArrayList();
        Consumer<Object> spy = o -> found.add(o);
        c.forEach(spy);
        assertTrue(found.isEmpty());

        assertTrue(c.add(x));
        c.forEach(spy);
        assertEquals(Collections.singletonList(x), found);
        found.clear();

        assertTrue(c.add(y));
        c.forEach(spy);
        assertEquals(2, found.size());
        assertTrue(found.contains(x));
        assertTrue(found.contains(y));
        found.clear();

        c.clear();
        c.forEach(spy);
        assertTrue(found.isEmpty());
    }

    /**
     * Motley crew of threads concurrently randomly hammer the collection.
     */
    public void testDetectRaces() throws Throwable {
        if (!impl.isConcurrent()) return;
        final ThreadLocalRandom rnd = ThreadLocalRandom.current();
        final Collection c = impl.emptyCollection();
        final long testDurationMillis = timeoutMillis();
        final AtomicBoolean done = new AtomicBoolean(false);
        final Object one = impl.makeElement(1);
        final Object two = impl.makeElement(2);
        final List<Future<?>> futures;
        final Phaser threadsStarted = new Phaser(1); // register this thread
        final Runnable[] frobbers = {
            () -> c.forEach(x -> assertTrue(x == one || x == two)),
            () -> c.stream().forEach(x -> assertTrue(x == one || x == two)),
            () -> c.spliterator().trySplit(),
            () -> {
                Spliterator s = c.spliterator();
                s.tryAdvance(x -> assertTrue(x == one || x == two));
                s.trySplit();
            },
            () -> {
                Spliterator s = c.spliterator();
                do {} while (s.tryAdvance(x -> assertTrue(x == one || x == two)));
            },
            () -> {
                for (Object x : c) assertTrue(x == one || x == two);
            },
            () -> {
                assertTrue(c.add(one));
                assertTrue(c.contains(one));
                assertTrue(c.remove(one));
                assertFalse(c.contains(one));
            },
            () -> {
                assertTrue(c.add(two));
                assertTrue(c.contains(two));
                assertTrue(c.remove(two));
                assertFalse(c.contains(two));
            },
        };
        final List<Runnable> tasks =
            Arrays.stream(frobbers)
            .filter(task -> rnd.nextBoolean()) // random subset
            .map(task -> (Runnable) () -> {
                     threadsStarted.arriveAndAwaitAdvance();
                     while (!done.get())
                         task.run();
                 })
            .collect(Collectors.toList());
        final ExecutorService pool = Executors.newCachedThreadPool();
        try (PoolCleaner cleaner = cleaner(pool, done)) {
            threadsStarted.bulkRegister(tasks.size());
            futures = tasks.stream()
                .map(pool::submit)
                .collect(Collectors.toList());
            threadsStarted.arriveAndDeregister();
            Thread.sleep(testDurationMillis);
        }
        for (Future future : futures)
            assertNull(future.get(0L, MILLISECONDS));
    }

//     public void testCollection8DebugFail() {
//         fail(impl.klazz().getSimpleName());
//     }
}
Revision:	1.28
Committed:	Fri Nov 18 17:23:29 2016 UTC (7 years, 5 months ago) by jsr166
Branch:	MAIN
Changes since 1.27:	+6 -6 lines
Log Message:	use Remi's rule: use a method reference if you can and a lambda otherwise
#	User	Rev	Content
1	jsr166	1.1	/*
2			* Written by Doug Lea and Martin Buchholz with assistance from
3			* members of JCP JSR-166 Expert Group and released to the public
4			* domain, as explained at
5			* http://creativecommons.org/publicdomain/zero/1.0/
6			*/
7
8	jsr166	1.16	import static java.util.concurrent.TimeUnit.HOURS;
9	jsr166	1.1	import static java.util.concurrent.TimeUnit.MILLISECONDS;
10
11			import java.util.ArrayList;
12	jsr166	1.18	import java.util.Arrays;
13	jsr166	1.1	import java.util.Collection;
14			import java.util.Collections;
15	jsr166	1.5	import java.util.Deque;
16			import java.util.HashSet;
17			import java.util.Iterator;
18			import java.util.List;
19			import java.util.NoSuchElementException;
20			import java.util.Queue;
21			import java.util.Spliterator;
22	jsr166	1.14	import java.util.concurrent.BlockingDeque;
23			import java.util.concurrent.BlockingQueue;
24	jsr166	1.2	import java.util.concurrent.CountDownLatch;
25	jsr166	1.1	import java.util.concurrent.Executors;
26			import java.util.concurrent.ExecutorService;
27			import java.util.concurrent.Future;
28	jsr166	1.26	import java.util.concurrent.Phaser;
29	jsr166	1.5	import java.util.concurrent.ThreadLocalRandom;
30	jsr166	1.1	import java.util.concurrent.atomic.AtomicBoolean;
31			import java.util.concurrent.atomic.AtomicLong;
32	jsr166	1.5	import java.util.concurrent.atomic.AtomicReference;
33	jsr166	1.1	import java.util.function.Consumer;
34	jsr166	1.5	import java.util.function.Predicate;
35	jsr166	1.26	import java.util.stream.Collectors;
36	jsr166	1.1
37			import junit.framework.Test;
38
39			/**
40			* Contains tests applicable to all jdk8+ Collection implementations.
41			* An extension of CollectionTest.
42			*/
43			public class Collection8Test extends JSR166TestCase {
44			final CollectionImplementation impl;
45
46			/** Tests are parameterized by a Collection implementation. */
47			Collection8Test(CollectionImplementation impl, String methodName) {
48			super(methodName);
49			this.impl = impl;
50			}
51
52			public static Test testSuite(CollectionImplementation impl) {
53			return parameterizedTestSuite(Collection8Test.class,
54			CollectionImplementation.class,
55			impl);
56			}
57
58	jsr166	1.10	Object bomb() {
59			return new Object() {
60			public boolean equals(Object x) { throw new AssertionError(); }
61			public int hashCode() { throw new AssertionError(); }
62			};
63			}
64
65	jsr166	1.5	/** Checks properties of empty collections. */
66	jsr166	1.24	public void testEmptyMeansEmpty() throws Throwable {
67	jsr166	1.5	Collection c = impl.emptyCollection();
68	jsr166	1.12	emptyMeansEmpty(c);
69
70	jsr166	1.24	if (c instanceof java.io.Serializable) {
71			try {
72			emptyMeansEmpty(serialClonePossiblyFailing(c));
73			} catch (java.io.NotSerializableException ex) {
74			// excusable when we have a serializable wrapper around
75			// a non-serializable collection, as can happen with:
76			// Vector.subList() => wrapped AbstractList$RandomAccessSubList
77			if (testImplementationDetails
78			&& (! c.getClass().getName().matches(
79			"java.util.Collections.*")))
80			throw ex;
81			}
82			}
83	jsr166	1.12
84			Collection clone = cloneableClone(c);
85			if (clone != null)
86			emptyMeansEmpty(clone);
87			}
88
89	jsr166	1.14	void emptyMeansEmpty(Collection c) throws InterruptedException {
90	jsr166	1.5	assertTrue(c.isEmpty());
91			assertEquals(0, c.size());
92			assertEquals("[]", c.toString());
93			{
94			Object[] a = c.toArray();
95			assertEquals(0, a.length);
96			assertSame(Object[].class, a.getClass());
97			}
98			{
99			Object[] a = new Object[0];
100			assertSame(a, c.toArray(a));
101			}
102			{
103			Integer[] a = new Integer[0];
104			assertSame(a, c.toArray(a));
105			}
106			{
107			Integer[] a = { 1, 2, 3};
108			assertSame(a, c.toArray(a));
109			assertNull(a[0]);
110			assertSame(2, a[1]);
111			assertSame(3, a[2]);
112			}
113			assertIteratorExhausted(c.iterator());
114	jsr166	1.19	Consumer alwaysThrows = e -> { throw new AssertionError(); };
115	jsr166	1.5	c.forEach(alwaysThrows);
116			c.iterator().forEachRemaining(alwaysThrows);
117			c.spliterator().forEachRemaining(alwaysThrows);
118			assertFalse(c.spliterator().tryAdvance(alwaysThrows));
119	jsr166	1.9	if (c.spliterator().hasCharacteristics(Spliterator.SIZED))
120			assertEquals(0, c.spliterator().estimateSize());
121	jsr166	1.10	assertFalse(c.contains(bomb()));
122			assertFalse(c.remove(bomb()));
123	jsr166	1.11	if (c instanceof Queue) {
124	jsr166	1.5	Queue q = (Queue) c;
125			assertNull(q.peek());
126			assertNull(q.poll());
127			}
128	jsr166	1.11	if (c instanceof Deque) {
129	jsr166	1.5	Deque d = (Deque) c;
130			assertNull(d.peekFirst());
131			assertNull(d.peekLast());
132			assertNull(d.pollFirst());
133			assertNull(d.pollLast());
134			assertIteratorExhausted(d.descendingIterator());
135	jsr166	1.9	d.descendingIterator().forEachRemaining(alwaysThrows);
136	jsr166	1.10	assertFalse(d.removeFirstOccurrence(bomb()));
137			assertFalse(d.removeLastOccurrence(bomb()));
138	jsr166	1.5	}
139	jsr166	1.14	if (c instanceof BlockingQueue) {
140			BlockingQueue q = (BlockingQueue) c;
141			assertNull(q.poll(0L, MILLISECONDS));
142			}
143			if (c instanceof BlockingDeque) {
144			BlockingDeque q = (BlockingDeque) c;
145			assertNull(q.pollFirst(0L, MILLISECONDS));
146			assertNull(q.pollLast(0L, MILLISECONDS));
147			}
148	jsr166	1.5	}
149
150	jsr166	1.14	public void testNullPointerExceptions() throws InterruptedException {
151	jsr166	1.5	Collection c = impl.emptyCollection();
152			assertThrows(
153			NullPointerException.class,
154			() -> c.addAll(null),
155			() -> c.containsAll(null),
156			() -> c.retainAll(null),
157			() -> c.removeAll(null),
158			() -> c.removeIf(null),
159	jsr166	1.6	() -> c.forEach(null),
160			() -> c.iterator().forEachRemaining(null),
161			() -> c.spliterator().forEachRemaining(null),
162			() -> c.spliterator().tryAdvance(null),
163	jsr166	1.5	() -> c.toArray(null));
164
165			if (!impl.permitsNulls()) {
166			assertThrows(
167			NullPointerException.class,
168			() -> c.add(null));
169			}
170	jsr166	1.14	if (!impl.permitsNulls() && c instanceof Queue) {
171	jsr166	1.5	Queue q = (Queue) c;
172			assertThrows(
173			NullPointerException.class,
174			() -> q.offer(null));
175			}
176	jsr166	1.14	if (!impl.permitsNulls() && c instanceof Deque) {
177	jsr166	1.5	Deque d = (Deque) c;
178			assertThrows(
179			NullPointerException.class,
180			() -> d.addFirst(null),
181			() -> d.addLast(null),
182			() -> d.offerFirst(null),
183			() -> d.offerLast(null),
184	jsr166	1.6	() -> d.push(null),
185			() -> d.descendingIterator().forEachRemaining(null));
186	jsr166	1.5	}
187	jsr166	1.15	if (c instanceof BlockingQueue) {
188	jsr166	1.14	BlockingQueue q = (BlockingQueue) c;
189			assertThrows(
190			NullPointerException.class,
191			() -> {
192	jsr166	1.16	try { q.offer(null, 1L, HOURS); }
193	jsr166	1.14	catch (InterruptedException ex) {
194			throw new AssertionError(ex);
195	jsr166	1.15	}},
196			() -> {
197			try { q.put(null); }
198			catch (InterruptedException ex) {
199			throw new AssertionError(ex);
200	jsr166	1.14	}});
201			}
202	jsr166	1.15	if (c instanceof BlockingDeque) {
203	jsr166	1.14	BlockingDeque q = (BlockingDeque) c;
204			assertThrows(
205			NullPointerException.class,
206			() -> {
207	jsr166	1.16	try { q.offerFirst(null, 1L, HOURS); }
208	jsr166	1.14	catch (InterruptedException ex) {
209			throw new AssertionError(ex);
210			}},
211			() -> {
212	jsr166	1.16	try { q.offerLast(null, 1L, HOURS); }
213	jsr166	1.14	catch (InterruptedException ex) {
214			throw new AssertionError(ex);
215	jsr166	1.15	}},
216			() -> {
217			try { q.putFirst(null); }
218			catch (InterruptedException ex) {
219			throw new AssertionError(ex);
220			}},
221			() -> {
222			try { q.putLast(null); }
223			catch (InterruptedException ex) {
224			throw new AssertionError(ex);
225	jsr166	1.14	}});
226			}
227	jsr166	1.5	}
228
229			public void testNoSuchElementExceptions() {
230			Collection c = impl.emptyCollection();
231			assertThrows(
232			NoSuchElementException.class,
233			() -> c.iterator().next());
234
235	jsr166	1.14	if (c instanceof Queue) {
236	jsr166	1.5	Queue q = (Queue) c;
237			assertThrows(
238			NoSuchElementException.class,
239			() -> q.element(),
240			() -> q.remove());
241			}
242	jsr166	1.14	if (c instanceof Deque) {
243	jsr166	1.5	Deque d = (Deque) c;
244			assertThrows(
245			NoSuchElementException.class,
246			() -> d.getFirst(),
247			() -> d.getLast(),
248			() -> d.removeFirst(),
249			() -> d.removeLast(),
250			() -> d.pop(),
251			() -> d.descendingIterator().next());
252			}
253			}
254
255			public void testRemoveIf() {
256			Collection c = impl.emptyCollection();
257	jsr166	1.22	boolean ordered =
258			c.spliterator().hasCharacteristics(Spliterator.ORDERED);
259	jsr166	1.5	ThreadLocalRandom rnd = ThreadLocalRandom.current();
260			int n = rnd.nextInt(6);
261			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
262			AtomicReference threwAt = new AtomicReference(null);
263	jsr166	1.18	List orig = rnd.nextBoolean()
264			? new ArrayList(c)
265			: Arrays.asList(c.toArray());
266
267			// Merely creating an iterator can change ArrayBlockingQueue behavior
268			Iterator it = rnd.nextBoolean() ? c.iterator() : null;
269
270			ArrayList survivors = new ArrayList();
271	jsr166	1.5	ArrayList accepts = new ArrayList();
272			ArrayList rejects = new ArrayList();
273	jsr166	1.18
274	jsr166	1.19	Predicate randomPredicate = e -> {
275	jsr166	1.5	assertNull(threwAt.get());
276			switch (rnd.nextInt(3)) {
277			case 0: accepts.add(e); return true;
278			case 1: rejects.add(e); return false;
279			case 2: threwAt.set(e); throw new ArithmeticException();
280			default: throw new AssertionError();
281			}
282			};
283			try {
284	jsr166	1.7	try {
285			boolean modified = c.removeIf(randomPredicate);
286	jsr166	1.18	assertNull(threwAt.get());
287			assertEquals(modified, accepts.size() > 0);
288			assertEquals(modified, rejects.size() != n);
289			assertEquals(accepts.size() + rejects.size(), n);
290	jsr166	1.22	if (ordered) {
291			assertEquals(rejects,
292			Arrays.asList(c.toArray()));
293			} else {
294			assertEquals(new HashSet(rejects),
295			new HashSet(Arrays.asList(c.toArray())));
296			}
297	jsr166	1.18	} catch (ArithmeticException ok) {
298			assertNotNull(threwAt.get());
299			assertTrue(c.contains(threwAt.get()));
300			}
301			if (it != null && impl.isConcurrent())
302			// check for weakly consistent iterator
303			while (it.hasNext()) assertTrue(orig.contains(it.next()));
304			switch (rnd.nextInt(4)) {
305			case 0: survivors.addAll(c); break;
306			case 1: survivors.addAll(Arrays.asList(c.toArray())); break;
307	jsr166	1.28	case 2: c.forEach(survivors::add); break;
308	jsr166	1.18	case 3: for (Object e : c) survivors.add(e); break;
309			}
310			assertTrue(orig.containsAll(accepts));
311			assertTrue(orig.containsAll(rejects));
312			assertTrue(orig.containsAll(survivors));
313			assertTrue(orig.containsAll(c));
314			assertTrue(c.containsAll(rejects));
315	jsr166	1.7	assertTrue(c.containsAll(survivors));
316			assertTrue(survivors.containsAll(rejects));
317	jsr166	1.22	if (threwAt.get() == null) {
318			assertEquals(n - accepts.size(), c.size());
319			for (Object x : accepts) assertFalse(c.contains(x));
320			} else {
321			// Two acceptable behaviors: entire removeIf call is one
322			// transaction, or each element processed is one transaction.
323			assertTrue(n == c.size() \|\| n == c.size() + accepts.size());
324			int k = 0;
325			for (Object x : accepts) if (c.contains(x)) k++;
326			assertTrue(k == accepts.size() \|\| k == 0);
327			}
328	jsr166	1.7	} catch (Throwable ex) {
329	jsr166	1.5	System.err.println(impl.klazz());
330	jsr166	1.23	// c is at risk of corruption if we got here, so be lenient
331			try { System.err.printf("c=%s%n", c); }
332			catch (Throwable t) { t.printStackTrace(); }
333	jsr166	1.7	System.err.printf("n=%d%n", n);
334	jsr166	1.18	System.err.printf("orig=%s%n", orig);
335	jsr166	1.7	System.err.printf("accepts=%s%n", accepts);
336			System.err.printf("rejects=%s%n", rejects);
337	jsr166	1.8	System.err.printf("survivors=%s%n", survivors);
338	jsr166	1.18	System.err.printf("threwAt=%s%n", threwAt.get());
339	jsr166	1.7	throw ex;
340	jsr166	1.5	}
341			}
342
343			/**
344			* Various ways of traversing a collection yield same elements
345			*/
346			public void testIteratorEquivalence() {
347			Collection c = impl.emptyCollection();
348			ThreadLocalRandom rnd = ThreadLocalRandom.current();
349			int n = rnd.nextInt(6);
350			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
351			ArrayList iterated = new ArrayList();
352			ArrayList iteratedForEachRemaining = new ArrayList();
353	jsr166	1.13	ArrayList tryAdvanced = new ArrayList();
354	jsr166	1.5	ArrayList spliterated = new ArrayList();
355	jsr166	1.13	ArrayList forEached = new ArrayList();
356			ArrayList removeIfed = new ArrayList();
357	jsr166	1.5	for (Object x : c) iterated.add(x);
358	jsr166	1.28	c.iterator().forEachRemaining(iteratedForEachRemaining::add);
359	jsr166	1.13	for (Spliterator s = c.spliterator();
360	jsr166	1.28	s.tryAdvance(tryAdvanced::add); ) {}
361			c.spliterator().forEachRemaining(spliterated::add);
362			c.forEach(forEached::add);
363	jsr166	1.13	c.removeIf(e -> { removeIfed.add(e); return false; });
364	jsr166	1.5	boolean ordered =
365			c.spliterator().hasCharacteristics(Spliterator.ORDERED);
366			if (c instanceof List \|\| c instanceof Deque)
367			assertTrue(ordered);
368			if (ordered) {
369			assertEquals(iterated, iteratedForEachRemaining);
370	jsr166	1.13	assertEquals(iterated, tryAdvanced);
371	jsr166	1.5	assertEquals(iterated, spliterated);
372	jsr166	1.13	assertEquals(iterated, forEached);
373			assertEquals(iterated, removeIfed);
374	jsr166	1.5	} else {
375			HashSet cset = new HashSet(c);
376			assertEquals(cset, new HashSet(iterated));
377			assertEquals(cset, new HashSet(iteratedForEachRemaining));
378	jsr166	1.13	assertEquals(cset, new HashSet(tryAdvanced));
379	jsr166	1.5	assertEquals(cset, new HashSet(spliterated));
380	jsr166	1.13	assertEquals(cset, new HashSet(forEached));
381			assertEquals(cset, new HashSet(removeIfed));
382	jsr166	1.5	}
383			if (c instanceof Deque) {
384			Deque d = (Deque) c;
385			ArrayList descending = new ArrayList();
386			ArrayList descendingForEachRemaining = new ArrayList();
387			for (Iterator it = d.descendingIterator(); it.hasNext(); )
388			descending.add(it.next());
389			d.descendingIterator().forEachRemaining(
390			e -> descendingForEachRemaining.add(e));
391			Collections.reverse(descending);
392			Collections.reverse(descendingForEachRemaining);
393			assertEquals(iterated, descending);
394			assertEquals(iterated, descendingForEachRemaining);
395			}
396			}
397
398			/**
399			* Calling Iterator#remove() after Iterator#forEachRemaining
400	jsr166	1.21	* should (maybe) remove last element
401	jsr166	1.5	*/
402			public void testRemoveAfterForEachRemaining() {
403			Collection c = impl.emptyCollection();
404			ThreadLocalRandom rnd = ThreadLocalRandom.current();
405	jsr166	1.25	testCollection: {
406	jsr166	1.5	int n = 3 + rnd.nextInt(2);
407			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
408			Iterator it = c.iterator();
409			assertTrue(it.hasNext());
410			assertEquals(impl.makeElement(0), it.next());
411			assertTrue(it.hasNext());
412			assertEquals(impl.makeElement(1), it.next());
413	jsr166	1.21	it.forEachRemaining(e -> assertTrue(c.contains(e)));
414			if (testImplementationDetails) {
415			if (c instanceof java.util.concurrent.ArrayBlockingQueue) {
416			assertIteratorExhausted(it);
417			} else {
418	jsr166	1.25	try { it.remove(); }
419			catch (UnsupportedOperationException ok) {
420			break testCollection;
421			}
422	jsr166	1.21	assertEquals(n - 1, c.size());
423			for (int i = 0; i < n - 1; i++)
424			assertTrue(c.contains(impl.makeElement(i)));
425			assertFalse(c.contains(impl.makeElement(n - 1)));
426			}
427			}
428	jsr166	1.5	}
429			if (c instanceof Deque) {
430			Deque d = (Deque) impl.emptyCollection();
431			int n = 3 + rnd.nextInt(2);
432			for (int i = 0; i < n; i++) d.add(impl.makeElement(i));
433			Iterator it = d.descendingIterator();
434			assertTrue(it.hasNext());
435			assertEquals(impl.makeElement(n - 1), it.next());
436			assertTrue(it.hasNext());
437			assertEquals(impl.makeElement(n - 2), it.next());
438	jsr166	1.21	it.forEachRemaining(e -> assertTrue(c.contains(e)));
439			if (testImplementationDetails) {
440			it.remove();
441			assertEquals(n - 1, d.size());
442			for (int i = 1; i < n; i++)
443			assertTrue(d.contains(impl.makeElement(i)));
444			assertFalse(d.contains(impl.makeElement(0)));
445			}
446	jsr166	1.5	}
447			}
448
449	jsr166	1.1	/**
450			* stream().forEach returns elements in the collection
451			*/
452	jsr166	1.3	public void testStreamForEach() throws Throwable {
453	jsr166	1.1	final Collection c = impl.emptyCollection();
454			final AtomicLong count = new AtomicLong(0L);
455			final Object x = impl.makeElement(1);
456			final Object y = impl.makeElement(2);
457			final ArrayList found = new ArrayList();
458	jsr166	1.20	Consumer<Object> spy = o -> found.add(o);
459	jsr166	1.1	c.stream().forEach(spy);
460			assertTrue(found.isEmpty());
461
462			assertTrue(c.add(x));
463			c.stream().forEach(spy);
464			assertEquals(Collections.singletonList(x), found);
465			found.clear();
466
467			assertTrue(c.add(y));
468			c.stream().forEach(spy);
469			assertEquals(2, found.size());
470			assertTrue(found.contains(x));
471			assertTrue(found.contains(y));
472			found.clear();
473
474			c.clear();
475			c.stream().forEach(spy);
476			assertTrue(found.isEmpty());
477			}
478
479	jsr166	1.3	public void testStreamForEachConcurrentStressTest() throws Throwable {
480			if (!impl.isConcurrent()) return;
481			final Collection c = impl.emptyCollection();
482			final long testDurationMillis = timeoutMillis();
483			final AtomicBoolean done = new AtomicBoolean(false);
484			final Object elt = impl.makeElement(1);
485			final Future<?> f1, f2;
486			final ExecutorService pool = Executors.newCachedThreadPool();
487			try (PoolCleaner cleaner = cleaner(pool, done)) {
488			final CountDownLatch threadsStarted = new CountDownLatch(2);
489			Runnable checkElt = () -> {
490			threadsStarted.countDown();
491			while (!done.get())
492	jsr166	1.20	c.stream().forEach(x -> assertSame(x, elt)); };
493	jsr166	1.3	Runnable addRemove = () -> {
494			threadsStarted.countDown();
495			while (!done.get()) {
496			assertTrue(c.add(elt));
497			assertTrue(c.remove(elt));
498			}};
499			f1 = pool.submit(checkElt);
500			f2 = pool.submit(addRemove);
501			Thread.sleep(testDurationMillis);
502			}
503			assertNull(f1.get(0L, MILLISECONDS));
504			assertNull(f2.get(0L, MILLISECONDS));
505			}
506
507			/**
508			* collection.forEach returns elements in the collection
509			*/
510			public void testForEach() throws Throwable {
511			final Collection c = impl.emptyCollection();
512			final AtomicLong count = new AtomicLong(0L);
513			final Object x = impl.makeElement(1);
514			final Object y = impl.makeElement(2);
515			final ArrayList found = new ArrayList();
516	jsr166	1.20	Consumer<Object> spy = o -> found.add(o);
517	jsr166	1.3	c.forEach(spy);
518			assertTrue(found.isEmpty());
519
520			assertTrue(c.add(x));
521			c.forEach(spy);
522			assertEquals(Collections.singletonList(x), found);
523			found.clear();
524
525			assertTrue(c.add(y));
526			c.forEach(spy);
527			assertEquals(2, found.size());
528			assertTrue(found.contains(x));
529			assertTrue(found.contains(y));
530			found.clear();
531
532			c.clear();
533			c.forEach(spy);
534			assertTrue(found.isEmpty());
535			}
536
537	jsr166	1.26	/**
538			* Motley crew of threads concurrently randomly hammer the collection.
539			*/
540			public void testDetectRaces() throws Throwable {
541	jsr166	1.1	if (!impl.isConcurrent()) return;
542	jsr166	1.26	final ThreadLocalRandom rnd = ThreadLocalRandom.current();
543	jsr166	1.1	final Collection c = impl.emptyCollection();
544	jsr166	1.2	final long testDurationMillis = timeoutMillis();
545	jsr166	1.1	final AtomicBoolean done = new AtomicBoolean(false);
546	jsr166	1.26	final Object one = impl.makeElement(1);
547			final Object two = impl.makeElement(2);
548			final List<Future<?>> futures;
549			final Phaser threadsStarted = new Phaser(1); // register this thread
550	jsr166	1.27	final Runnable[] frobbers = {
551	jsr166	1.26	() -> c.forEach(x -> assertTrue(x == one \|\| x == two)),
552			() -> c.stream().forEach(x -> assertTrue(x == one \|\| x == two)),
553			() -> c.spliterator().trySplit(),
554			() -> {
555			Spliterator s = c.spliterator();
556			s.tryAdvance(x -> assertTrue(x == one \|\| x == two));
557			s.trySplit();
558			},
559			() -> {
560			Spliterator s = c.spliterator();
561			do {} while (s.tryAdvance(x -> assertTrue(x == one \|\| x == two)));
562			},
563			() -> {
564			for (Object x : c) assertTrue(x == one \|\| x == two);
565			},
566			() -> {
567			assertTrue(c.add(one));
568			assertTrue(c.contains(one));
569			assertTrue(c.remove(one));
570			assertFalse(c.contains(one));
571			},
572			() -> {
573			assertTrue(c.add(two));
574			assertTrue(c.contains(two));
575			assertTrue(c.remove(two));
576			assertFalse(c.contains(two));
577	jsr166	1.27	},
578			};
579			final List<Runnable> tasks =
580			Arrays.stream(frobbers)
581	jsr166	1.26	.filter(task -> rnd.nextBoolean()) // random subset
582			.map(task -> (Runnable) () -> {
583			threadsStarted.arriveAndAwaitAdvance();
584			while (!done.get())
585			task.run();
586			})
587			.collect(Collectors.toList());
588	jsr166	1.2	final ExecutorService pool = Executors.newCachedThreadPool();
589			try (PoolCleaner cleaner = cleaner(pool, done)) {
590	jsr166	1.26	threadsStarted.bulkRegister(tasks.size());
591			futures = tasks.stream()
592	jsr166	1.28	.map(pool::submit)
593	jsr166	1.26	.collect(Collectors.toList());
594			threadsStarted.arriveAndDeregister();
595	jsr166	1.2	Thread.sleep(testDurationMillis);
596			}
597	jsr166	1.26	for (Future future : futures)
598			assertNull(future.get(0L, MILLISECONDS));
599	jsr166	1.1	}
600
601	jsr166	1.4	// public void testCollection8DebugFail() {
602			// fail(impl.klazz().getSimpleName());
603			// }
604	jsr166	1.1	}