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.MILLISECONDS;

import java.util.ArrayList;
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.CountDownLatch;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
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 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);
    }

    /** Checks properties of empty collections. */
    public void testEmptyMeansEmpty() {
        Collection c = impl.emptyCollection();
        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 (Queue.class.isAssignableFrom(impl.klazz())) {
            Queue q = (Queue) c;
            assertNull(q.peek());
            assertNull(q.poll());
        }
        if (Deque.class.isAssignableFrom(impl.klazz())) {
            Deque d = (Deque) c;
            assertNull(d.peekFirst());
            assertNull(d.peekLast());
            assertNull(d.pollFirst());
            assertNull(d.pollLast());
            assertIteratorExhausted(d.descendingIterator());
        }
    }

    public void testNullPointerExceptions() {
        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()
            && Queue.class.isAssignableFrom(impl.klazz())) {
            Queue q = (Queue) c;
            assertThrows(
                NullPointerException.class,
                () -> q.offer(null));
        }
        if (!impl.permitsNulls()
            && Deque.class.isAssignableFrom(impl.klazz())) {
            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));
        }
    }

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

        if (Queue.class.isAssignableFrom(impl.klazz())) {
            Queue q = (Queue) c;
            assertThrows(
                NoSuchElementException.class,
                () -> q.element(),
                () -> q.remove());
        }
        if (Deque.class.isAssignableFrom(impl.klazz())) {
            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();
        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);
        ArrayList survivors = new ArrayList(c);
        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 {
            assertFalse(survivors.contains(null));
            try {
                boolean modified = c.removeIf(randomPredicate);
                if (!modified) {
                    assertNull(threwAt.get());
                    assertEquals(n, rejects.size());
                    assertEquals(0, accepts.size());
                }
            } catch (ArithmeticException ok) {}
            survivors.removeAll(accepts);
            assertEquals(n - accepts.size(), c.size());
            assertTrue(c.containsAll(survivors));
            assertTrue(survivors.containsAll(rejects));
            for (Object x : accepts) assertFalse(c.contains(x));
            if (threwAt.get() == null)
                assertEquals(accepts.size() + rejects.size(), n);
        } catch (Throwable ex) {
            System.err.println(impl.klazz());
            System.err.printf("c=%s%n", c);
            System.err.printf("n=%d%n", n);
            System.err.printf("accepts=%s%n", accepts);
            System.err.printf("rejects=%s%n", rejects);
            System.err.printf("survivors=%s%n", survivors);
            System.err.printf("threw=%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 spliterated = new ArrayList();
        ArrayList foreached = new ArrayList();
        for (Object x : c) iterated.add(x);
        c.iterator().forEachRemaining(e -> iteratedForEachRemaining.add(e));
        c.spliterator().forEachRemaining(e -> spliterated.add(e));
        c.forEach(e -> foreached.add(e));
        boolean ordered =
            c.spliterator().hasCharacteristics(Spliterator.ORDERED);
        if (c instanceof List || c instanceof Deque)
            assertTrue(ordered);
        if (ordered) {
            assertEquals(iterated, iteratedForEachRemaining);
            assertEquals(iterated, spliterated);
            assertEquals(iterated, foreached);
        } else {
            HashSet cset = new HashSet(c);
            assertEquals(cset, new HashSet(iterated));
            assertEquals(cset, new HashSet(iteratedForEachRemaining));
            assertEquals(cset, new HashSet(spliterated));
            assertEquals(cset, new HashSet(foreached));
        }
        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 remove last element
     */
    public void testRemoveAfterForEachRemaining() {
        Collection c = impl.emptyCollection();
        ThreadLocalRandom rnd = ThreadLocalRandom.current();
        {
            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) -> {});
            it.remove();
            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) -> {});
            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());
    }

    public void testForEachConcurrentStressTest() 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.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));
    }

//     public void testCollection8DebugFail() {
//         fail(impl.klazz().getSimpleName());
//     }
}
Revision:	1.8
Committed:	Thu Nov 3 15:31:25 2016 UTC (7 years, 6 months ago) by jsr166
Branch:	MAIN
Changes since 1.7:	+2 -1 lines
Log Message:	improve testRemoveIf
#	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			import static java.util.concurrent.TimeUnit.MILLISECONDS;
9
10			import java.util.ArrayList;
11			import java.util.Collection;
12			import java.util.Collections;
13	jsr166	1.5	import java.util.Deque;
14			import java.util.HashSet;
15			import java.util.Iterator;
16			import java.util.List;
17			import java.util.NoSuchElementException;
18			import java.util.Queue;
19			import java.util.Spliterator;
20	jsr166	1.2	import java.util.concurrent.CountDownLatch;
21	jsr166	1.1	import java.util.concurrent.Executors;
22			import java.util.concurrent.ExecutorService;
23			import java.util.concurrent.Future;
24	jsr166	1.5	import java.util.concurrent.ThreadLocalRandom;
25	jsr166	1.1	import java.util.concurrent.atomic.AtomicBoolean;
26			import java.util.concurrent.atomic.AtomicLong;
27	jsr166	1.5	import java.util.concurrent.atomic.AtomicReference;
28	jsr166	1.1	import java.util.function.Consumer;
29	jsr166	1.5	import java.util.function.Predicate;
30	jsr166	1.1
31			import junit.framework.Test;
32
33			/**
34			* Contains tests applicable to all jdk8+ Collection implementations.
35			* An extension of CollectionTest.
36			*/
37			public class Collection8Test extends JSR166TestCase {
38			final CollectionImplementation impl;
39
40			/** Tests are parameterized by a Collection implementation. */
41			Collection8Test(CollectionImplementation impl, String methodName) {
42			super(methodName);
43			this.impl = impl;
44			}
45
46			public static Test testSuite(CollectionImplementation impl) {
47			return parameterizedTestSuite(Collection8Test.class,
48			CollectionImplementation.class,
49			impl);
50			}
51
52	jsr166	1.5	/** Checks properties of empty collections. */
53			public void testEmptyMeansEmpty() {
54			Collection c = impl.emptyCollection();
55			assertTrue(c.isEmpty());
56			assertEquals(0, c.size());
57			assertEquals("[]", c.toString());
58			{
59			Object[] a = c.toArray();
60			assertEquals(0, a.length);
61			assertSame(Object[].class, a.getClass());
62			}
63			{
64			Object[] a = new Object[0];
65			assertSame(a, c.toArray(a));
66			}
67			{
68			Integer[] a = new Integer[0];
69			assertSame(a, c.toArray(a));
70			}
71			{
72			Integer[] a = { 1, 2, 3};
73			assertSame(a, c.toArray(a));
74			assertNull(a[0]);
75			assertSame(2, a[1]);
76			assertSame(3, a[2]);
77			}
78			assertIteratorExhausted(c.iterator());
79			Consumer alwaysThrows = (e) -> { throw new AssertionError(); };
80			c.forEach(alwaysThrows);
81			c.iterator().forEachRemaining(alwaysThrows);
82			c.spliterator().forEachRemaining(alwaysThrows);
83			assertFalse(c.spliterator().tryAdvance(alwaysThrows));
84			if (Queue.class.isAssignableFrom(impl.klazz())) {
85			Queue q = (Queue) c;
86			assertNull(q.peek());
87			assertNull(q.poll());
88			}
89			if (Deque.class.isAssignableFrom(impl.klazz())) {
90			Deque d = (Deque) c;
91			assertNull(d.peekFirst());
92			assertNull(d.peekLast());
93			assertNull(d.pollFirst());
94			assertNull(d.pollLast());
95			assertIteratorExhausted(d.descendingIterator());
96			}
97			}
98
99			public void testNullPointerExceptions() {
100			Collection c = impl.emptyCollection();
101			assertThrows(
102			NullPointerException.class,
103			() -> c.addAll(null),
104			() -> c.containsAll(null),
105			() -> c.retainAll(null),
106			() -> c.removeAll(null),
107			() -> c.removeIf(null),
108	jsr166	1.6	() -> c.forEach(null),
109			() -> c.iterator().forEachRemaining(null),
110			() -> c.spliterator().forEachRemaining(null),
111			() -> c.spliterator().tryAdvance(null),
112	jsr166	1.5	() -> c.toArray(null));
113
114			if (!impl.permitsNulls()) {
115			assertThrows(
116			NullPointerException.class,
117			() -> c.add(null));
118			}
119			if (!impl.permitsNulls()
120			&& Queue.class.isAssignableFrom(impl.klazz())) {
121			Queue q = (Queue) c;
122			assertThrows(
123			NullPointerException.class,
124			() -> q.offer(null));
125			}
126			if (!impl.permitsNulls()
127			&& Deque.class.isAssignableFrom(impl.klazz())) {
128			Deque d = (Deque) c;
129			assertThrows(
130			NullPointerException.class,
131			() -> d.addFirst(null),
132			() -> d.addLast(null),
133			() -> d.offerFirst(null),
134			() -> d.offerLast(null),
135	jsr166	1.6	() -> d.push(null),
136			() -> d.descendingIterator().forEachRemaining(null));
137	jsr166	1.5	}
138			}
139
140			public void testNoSuchElementExceptions() {
141			Collection c = impl.emptyCollection();
142			assertThrows(
143			NoSuchElementException.class,
144			() -> c.iterator().next());
145
146			if (Queue.class.isAssignableFrom(impl.klazz())) {
147			Queue q = (Queue) c;
148			assertThrows(
149			NoSuchElementException.class,
150			() -> q.element(),
151			() -> q.remove());
152			}
153			if (Deque.class.isAssignableFrom(impl.klazz())) {
154			Deque d = (Deque) c;
155			assertThrows(
156			NoSuchElementException.class,
157			() -> d.getFirst(),
158			() -> d.getLast(),
159			() -> d.removeFirst(),
160			() -> d.removeLast(),
161			() -> d.pop(),
162			() -> d.descendingIterator().next());
163			}
164			}
165
166			public void testRemoveIf() {
167			Collection c = impl.emptyCollection();
168			ThreadLocalRandom rnd = ThreadLocalRandom.current();
169			int n = rnd.nextInt(6);
170			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
171			AtomicReference threwAt = new AtomicReference(null);
172			ArrayList survivors = new ArrayList(c);
173			ArrayList accepts = new ArrayList();
174			ArrayList rejects = new ArrayList();
175			Predicate randomPredicate = (e) -> {
176			assertNull(threwAt.get());
177			switch (rnd.nextInt(3)) {
178			case 0: accepts.add(e); return true;
179			case 1: rejects.add(e); return false;
180			case 2: threwAt.set(e); throw new ArithmeticException();
181			default: throw new AssertionError();
182			}
183			};
184			try {
185	jsr166	1.8	assertFalse(survivors.contains(null));
186	jsr166	1.7	try {
187			boolean modified = c.removeIf(randomPredicate);
188			if (!modified) {
189			assertNull(threwAt.get());
190			assertEquals(n, rejects.size());
191			assertEquals(0, accepts.size());
192			}
193			} catch (ArithmeticException ok) {}
194			survivors.removeAll(accepts);
195			assertEquals(n - accepts.size(), c.size());
196			assertTrue(c.containsAll(survivors));
197			assertTrue(survivors.containsAll(rejects));
198			for (Object x : accepts) assertFalse(c.contains(x));
199			if (threwAt.get() == null)
200			assertEquals(accepts.size() + rejects.size(), n);
201			} catch (Throwable ex) {
202	jsr166	1.5	System.err.println(impl.klazz());
203	jsr166	1.7	System.err.printf("c=%s%n", c);
204			System.err.printf("n=%d%n", n);
205			System.err.printf("accepts=%s%n", accepts);
206			System.err.printf("rejects=%s%n", rejects);
207	jsr166	1.8	System.err.printf("survivors=%s%n", survivors);
208	jsr166	1.7	System.err.printf("threw=%s%n", threwAt.get());
209			throw ex;
210	jsr166	1.5	}
211			}
212
213			/**
214			* Various ways of traversing a collection yield same elements
215			*/
216			public void testIteratorEquivalence() {
217			Collection c = impl.emptyCollection();
218			ThreadLocalRandom rnd = ThreadLocalRandom.current();
219			int n = rnd.nextInt(6);
220			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
221			ArrayList iterated = new ArrayList();
222			ArrayList iteratedForEachRemaining = new ArrayList();
223			ArrayList spliterated = new ArrayList();
224			ArrayList foreached = new ArrayList();
225			for (Object x : c) iterated.add(x);
226			c.iterator().forEachRemaining(e -> iteratedForEachRemaining.add(e));
227			c.spliterator().forEachRemaining(e -> spliterated.add(e));
228			c.forEach(e -> foreached.add(e));
229			boolean ordered =
230			c.spliterator().hasCharacteristics(Spliterator.ORDERED);
231			if (c instanceof List \|\| c instanceof Deque)
232			assertTrue(ordered);
233			if (ordered) {
234			assertEquals(iterated, iteratedForEachRemaining);
235			assertEquals(iterated, spliterated);
236			assertEquals(iterated, foreached);
237			} else {
238			HashSet cset = new HashSet(c);
239			assertEquals(cset, new HashSet(iterated));
240			assertEquals(cset, new HashSet(iteratedForEachRemaining));
241			assertEquals(cset, new HashSet(spliterated));
242			assertEquals(cset, new HashSet(foreached));
243			}
244			if (c instanceof Deque) {
245			Deque d = (Deque) c;
246			ArrayList descending = new ArrayList();
247			ArrayList descendingForEachRemaining = new ArrayList();
248			for (Iterator it = d.descendingIterator(); it.hasNext(); )
249			descending.add(it.next());
250			d.descendingIterator().forEachRemaining(
251			e -> descendingForEachRemaining.add(e));
252			Collections.reverse(descending);
253			Collections.reverse(descendingForEachRemaining);
254			assertEquals(iterated, descending);
255			assertEquals(iterated, descendingForEachRemaining);
256			}
257			}
258
259			/**
260			* Calling Iterator#remove() after Iterator#forEachRemaining
261			* should remove last element
262			*/
263			public void testRemoveAfterForEachRemaining() {
264			Collection c = impl.emptyCollection();
265			ThreadLocalRandom rnd = ThreadLocalRandom.current();
266			{
267			int n = 3 + rnd.nextInt(2);
268			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
269			Iterator it = c.iterator();
270			assertTrue(it.hasNext());
271			assertEquals(impl.makeElement(0), it.next());
272			assertTrue(it.hasNext());
273			assertEquals(impl.makeElement(1), it.next());
274			it.forEachRemaining((e) -> {});
275			it.remove();
276			assertEquals(n - 1, c.size());
277			for (int i = 0; i < n - 1; i++)
278			assertTrue(c.contains(impl.makeElement(i)));
279			assertFalse(c.contains(impl.makeElement(n - 1)));
280			}
281			if (c instanceof Deque) {
282			Deque d = (Deque) impl.emptyCollection();
283			int n = 3 + rnd.nextInt(2);
284			for (int i = 0; i < n; i++) d.add(impl.makeElement(i));
285			Iterator it = d.descendingIterator();
286			assertTrue(it.hasNext());
287			assertEquals(impl.makeElement(n - 1), it.next());
288			assertTrue(it.hasNext());
289			assertEquals(impl.makeElement(n - 2), it.next());
290			it.forEachRemaining((e) -> {});
291			it.remove();
292			assertEquals(n - 1, d.size());
293			for (int i = 1; i < n; i++)
294			assertTrue(d.contains(impl.makeElement(i)));
295			assertFalse(d.contains(impl.makeElement(0)));
296			}
297			}
298
299	jsr166	1.1	/**
300			* stream().forEach returns elements in the collection
301			*/
302	jsr166	1.3	public void testStreamForEach() throws Throwable {
303	jsr166	1.1	final Collection c = impl.emptyCollection();
304			final AtomicLong count = new AtomicLong(0L);
305			final Object x = impl.makeElement(1);
306			final Object y = impl.makeElement(2);
307			final ArrayList found = new ArrayList();
308			Consumer<Object> spy = (o) -> { found.add(o); };
309			c.stream().forEach(spy);
310			assertTrue(found.isEmpty());
311
312			assertTrue(c.add(x));
313			c.stream().forEach(spy);
314			assertEquals(Collections.singletonList(x), found);
315			found.clear();
316
317			assertTrue(c.add(y));
318			c.stream().forEach(spy);
319			assertEquals(2, found.size());
320			assertTrue(found.contains(x));
321			assertTrue(found.contains(y));
322			found.clear();
323
324			c.clear();
325			c.stream().forEach(spy);
326			assertTrue(found.isEmpty());
327			}
328
329	jsr166	1.3	public void testStreamForEachConcurrentStressTest() throws Throwable {
330			if (!impl.isConcurrent()) return;
331			final Collection c = impl.emptyCollection();
332			final long testDurationMillis = timeoutMillis();
333			final AtomicBoolean done = new AtomicBoolean(false);
334			final Object elt = impl.makeElement(1);
335			final Future<?> f1, f2;
336			final ExecutorService pool = Executors.newCachedThreadPool();
337			try (PoolCleaner cleaner = cleaner(pool, done)) {
338			final CountDownLatch threadsStarted = new CountDownLatch(2);
339			Runnable checkElt = () -> {
340			threadsStarted.countDown();
341			while (!done.get())
342			c.stream().forEach((x) -> { assertSame(x, elt); }); };
343			Runnable addRemove = () -> {
344			threadsStarted.countDown();
345			while (!done.get()) {
346			assertTrue(c.add(elt));
347			assertTrue(c.remove(elt));
348			}};
349			f1 = pool.submit(checkElt);
350			f2 = pool.submit(addRemove);
351			Thread.sleep(testDurationMillis);
352			}
353			assertNull(f1.get(0L, MILLISECONDS));
354			assertNull(f2.get(0L, MILLISECONDS));
355			}
356
357			/**
358			* collection.forEach returns elements in the collection
359			*/
360			public void testForEach() throws Throwable {
361			final Collection c = impl.emptyCollection();
362			final AtomicLong count = new AtomicLong(0L);
363			final Object x = impl.makeElement(1);
364			final Object y = impl.makeElement(2);
365			final ArrayList found = new ArrayList();
366			Consumer<Object> spy = (o) -> { found.add(o); };
367			c.forEach(spy);
368			assertTrue(found.isEmpty());
369
370			assertTrue(c.add(x));
371			c.forEach(spy);
372			assertEquals(Collections.singletonList(x), found);
373			found.clear();
374
375			assertTrue(c.add(y));
376			c.forEach(spy);
377			assertEquals(2, found.size());
378			assertTrue(found.contains(x));
379			assertTrue(found.contains(y));
380			found.clear();
381
382			c.clear();
383			c.forEach(spy);
384			assertTrue(found.isEmpty());
385			}
386
387	jsr166	1.1	public void testForEachConcurrentStressTest() throws Throwable {
388			if (!impl.isConcurrent()) return;
389			final Collection c = impl.emptyCollection();
390	jsr166	1.2	final long testDurationMillis = timeoutMillis();
391	jsr166	1.1	final AtomicBoolean done = new AtomicBoolean(false);
392			final Object elt = impl.makeElement(1);
393	jsr166	1.2	final Future<?> f1, f2;
394			final ExecutorService pool = Executors.newCachedThreadPool();
395			try (PoolCleaner cleaner = cleaner(pool, done)) {
396			final CountDownLatch threadsStarted = new CountDownLatch(2);
397			Runnable checkElt = () -> {
398			threadsStarted.countDown();
399			while (!done.get())
400	jsr166	1.3	c.forEach((x) -> { assertSame(x, elt); }); };
401	jsr166	1.2	Runnable addRemove = () -> {
402			threadsStarted.countDown();
403			while (!done.get()) {
404			assertTrue(c.add(elt));
405			assertTrue(c.remove(elt));
406			}};
407			f1 = pool.submit(checkElt);
408			f2 = pool.submit(addRemove);
409			Thread.sleep(testDurationMillis);
410			}
411			assertNull(f1.get(0L, MILLISECONDS));
412			assertNull(f2.get(0L, MILLISECONDS));
413	jsr166	1.1	}
414
415	jsr166	1.4	// public void testCollection8DebugFail() {
416			// fail(impl.klazz().getSimpleName());
417			// }
418	jsr166	1.1	}