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);
    }

    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() {
        Collection c = impl.emptyCollection();
        emptyMeansEmpty(c);

        if (c instanceof java.io.Serializable)
            emptyMeansEmpty(serialClone(c));

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

    void emptyMeansEmpty(Collection c) {
        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()));
        }
    }

    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:	1.12
Committed:	Sat Nov 5 16:10:38 2016 UTC (7 years, 6 months ago) by jsr166
Branch:	MAIN
Changes since 1.11:	+11 -0 lines
Log Message:	test clones of empty collections
#	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	1.10	Object bomb() {
53			return new Object() {
54			public boolean equals(Object x) { throw new AssertionError(); }
55			public int hashCode() { throw new AssertionError(); }
56			};
57			}
58
59	jsr166	1.5	/** Checks properties of empty collections. */
60			public void testEmptyMeansEmpty() {
61			Collection c = impl.emptyCollection();
62	jsr166	1.12	emptyMeansEmpty(c);
63
64			if (c instanceof java.io.Serializable)
65			emptyMeansEmpty(serialClone(c));
66
67			Collection clone = cloneableClone(c);
68			if (clone != null)
69			emptyMeansEmpty(clone);
70			}
71
72			void emptyMeansEmpty(Collection c) {
73	jsr166	1.5	assertTrue(c.isEmpty());
74			assertEquals(0, c.size());
75			assertEquals("[]", c.toString());
76			{
77			Object[] a = c.toArray();
78			assertEquals(0, a.length);
79			assertSame(Object[].class, a.getClass());
80			}
81			{
82			Object[] a = new Object[0];
83			assertSame(a, c.toArray(a));
84			}
85			{
86			Integer[] a = new Integer[0];
87			assertSame(a, c.toArray(a));
88			}
89			{
90			Integer[] a = { 1, 2, 3};
91			assertSame(a, c.toArray(a));
92			assertNull(a[0]);
93			assertSame(2, a[1]);
94			assertSame(3, a[2]);
95			}
96			assertIteratorExhausted(c.iterator());
97			Consumer alwaysThrows = (e) -> { throw new AssertionError(); };
98			c.forEach(alwaysThrows);
99			c.iterator().forEachRemaining(alwaysThrows);
100			c.spliterator().forEachRemaining(alwaysThrows);
101			assertFalse(c.spliterator().tryAdvance(alwaysThrows));
102	jsr166	1.9	if (c.spliterator().hasCharacteristics(Spliterator.SIZED))
103			assertEquals(0, c.spliterator().estimateSize());
104	jsr166	1.10	assertFalse(c.contains(bomb()));
105			assertFalse(c.remove(bomb()));
106	jsr166	1.11	if (c instanceof Queue) {
107	jsr166	1.5	Queue q = (Queue) c;
108			assertNull(q.peek());
109			assertNull(q.poll());
110			}
111	jsr166	1.11	if (c instanceof Deque) {
112	jsr166	1.5	Deque d = (Deque) c;
113			assertNull(d.peekFirst());
114			assertNull(d.peekLast());
115			assertNull(d.pollFirst());
116			assertNull(d.pollLast());
117			assertIteratorExhausted(d.descendingIterator());
118	jsr166	1.9	d.descendingIterator().forEachRemaining(alwaysThrows);
119	jsr166	1.10	assertFalse(d.removeFirstOccurrence(bomb()));
120			assertFalse(d.removeLastOccurrence(bomb()));
121	jsr166	1.5	}
122			}
123
124			public void testNullPointerExceptions() {
125			Collection c = impl.emptyCollection();
126			assertThrows(
127			NullPointerException.class,
128			() -> c.addAll(null),
129			() -> c.containsAll(null),
130			() -> c.retainAll(null),
131			() -> c.removeAll(null),
132			() -> c.removeIf(null),
133	jsr166	1.6	() -> c.forEach(null),
134			() -> c.iterator().forEachRemaining(null),
135			() -> c.spliterator().forEachRemaining(null),
136			() -> c.spliterator().tryAdvance(null),
137	jsr166	1.5	() -> c.toArray(null));
138
139			if (!impl.permitsNulls()) {
140			assertThrows(
141			NullPointerException.class,
142			() -> c.add(null));
143			}
144			if (!impl.permitsNulls()
145			&& Queue.class.isAssignableFrom(impl.klazz())) {
146			Queue q = (Queue) c;
147			assertThrows(
148			NullPointerException.class,
149			() -> q.offer(null));
150			}
151			if (!impl.permitsNulls()
152			&& Deque.class.isAssignableFrom(impl.klazz())) {
153			Deque d = (Deque) c;
154			assertThrows(
155			NullPointerException.class,
156			() -> d.addFirst(null),
157			() -> d.addLast(null),
158			() -> d.offerFirst(null),
159			() -> d.offerLast(null),
160	jsr166	1.6	() -> d.push(null),
161			() -> d.descendingIterator().forEachRemaining(null));
162	jsr166	1.5	}
163			}
164
165			public void testNoSuchElementExceptions() {
166			Collection c = impl.emptyCollection();
167			assertThrows(
168			NoSuchElementException.class,
169			() -> c.iterator().next());
170
171			if (Queue.class.isAssignableFrom(impl.klazz())) {
172			Queue q = (Queue) c;
173			assertThrows(
174			NoSuchElementException.class,
175			() -> q.element(),
176			() -> q.remove());
177			}
178			if (Deque.class.isAssignableFrom(impl.klazz())) {
179			Deque d = (Deque) c;
180			assertThrows(
181			NoSuchElementException.class,
182			() -> d.getFirst(),
183			() -> d.getLast(),
184			() -> d.removeFirst(),
185			() -> d.removeLast(),
186			() -> d.pop(),
187			() -> d.descendingIterator().next());
188			}
189			}
190
191			public void testRemoveIf() {
192			Collection c = impl.emptyCollection();
193			ThreadLocalRandom rnd = ThreadLocalRandom.current();
194			int n = rnd.nextInt(6);
195			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
196			AtomicReference threwAt = new AtomicReference(null);
197			ArrayList survivors = new ArrayList(c);
198			ArrayList accepts = new ArrayList();
199			ArrayList rejects = new ArrayList();
200			Predicate randomPredicate = (e) -> {
201			assertNull(threwAt.get());
202			switch (rnd.nextInt(3)) {
203			case 0: accepts.add(e); return true;
204			case 1: rejects.add(e); return false;
205			case 2: threwAt.set(e); throw new ArithmeticException();
206			default: throw new AssertionError();
207			}
208			};
209			try {
210	jsr166	1.8	assertFalse(survivors.contains(null));
211	jsr166	1.7	try {
212			boolean modified = c.removeIf(randomPredicate);
213			if (!modified) {
214			assertNull(threwAt.get());
215			assertEquals(n, rejects.size());
216			assertEquals(0, accepts.size());
217			}
218			} catch (ArithmeticException ok) {}
219			survivors.removeAll(accepts);
220			assertEquals(n - accepts.size(), c.size());
221			assertTrue(c.containsAll(survivors));
222			assertTrue(survivors.containsAll(rejects));
223			for (Object x : accepts) assertFalse(c.contains(x));
224			if (threwAt.get() == null)
225			assertEquals(accepts.size() + rejects.size(), n);
226			} catch (Throwable ex) {
227	jsr166	1.5	System.err.println(impl.klazz());
228	jsr166	1.7	System.err.printf("c=%s%n", c);
229			System.err.printf("n=%d%n", n);
230			System.err.printf("accepts=%s%n", accepts);
231			System.err.printf("rejects=%s%n", rejects);
232	jsr166	1.8	System.err.printf("survivors=%s%n", survivors);
233	jsr166	1.7	System.err.printf("threw=%s%n", threwAt.get());
234			throw ex;
235	jsr166	1.5	}
236			}
237
238			/**
239			* Various ways of traversing a collection yield same elements
240			*/
241			public void testIteratorEquivalence() {
242			Collection c = impl.emptyCollection();
243			ThreadLocalRandom rnd = ThreadLocalRandom.current();
244			int n = rnd.nextInt(6);
245			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
246			ArrayList iterated = new ArrayList();
247			ArrayList iteratedForEachRemaining = new ArrayList();
248			ArrayList spliterated = new ArrayList();
249			ArrayList foreached = new ArrayList();
250			for (Object x : c) iterated.add(x);
251			c.iterator().forEachRemaining(e -> iteratedForEachRemaining.add(e));
252			c.spliterator().forEachRemaining(e -> spliterated.add(e));
253			c.forEach(e -> foreached.add(e));
254			boolean ordered =
255			c.spliterator().hasCharacteristics(Spliterator.ORDERED);
256			if (c instanceof List \|\| c instanceof Deque)
257			assertTrue(ordered);
258			if (ordered) {
259			assertEquals(iterated, iteratedForEachRemaining);
260			assertEquals(iterated, spliterated);
261			assertEquals(iterated, foreached);
262			} else {
263			HashSet cset = new HashSet(c);
264			assertEquals(cset, new HashSet(iterated));
265			assertEquals(cset, new HashSet(iteratedForEachRemaining));
266			assertEquals(cset, new HashSet(spliterated));
267			assertEquals(cset, new HashSet(foreached));
268			}
269			if (c instanceof Deque) {
270			Deque d = (Deque) c;
271			ArrayList descending = new ArrayList();
272			ArrayList descendingForEachRemaining = new ArrayList();
273			for (Iterator it = d.descendingIterator(); it.hasNext(); )
274			descending.add(it.next());
275			d.descendingIterator().forEachRemaining(
276			e -> descendingForEachRemaining.add(e));
277			Collections.reverse(descending);
278			Collections.reverse(descendingForEachRemaining);
279			assertEquals(iterated, descending);
280			assertEquals(iterated, descendingForEachRemaining);
281			}
282			}
283
284			/**
285			* Calling Iterator#remove() after Iterator#forEachRemaining
286			* should remove last element
287			*/
288			public void testRemoveAfterForEachRemaining() {
289			Collection c = impl.emptyCollection();
290			ThreadLocalRandom rnd = ThreadLocalRandom.current();
291			{
292			int n = 3 + rnd.nextInt(2);
293			for (int i = 0; i < n; i++) c.add(impl.makeElement(i));
294			Iterator it = c.iterator();
295			assertTrue(it.hasNext());
296			assertEquals(impl.makeElement(0), it.next());
297			assertTrue(it.hasNext());
298			assertEquals(impl.makeElement(1), it.next());
299			it.forEachRemaining((e) -> {});
300			it.remove();
301			assertEquals(n - 1, c.size());
302			for (int i = 0; i < n - 1; i++)
303			assertTrue(c.contains(impl.makeElement(i)));
304			assertFalse(c.contains(impl.makeElement(n - 1)));
305			}
306			if (c instanceof Deque) {
307			Deque d = (Deque) impl.emptyCollection();
308			int n = 3 + rnd.nextInt(2);
309			for (int i = 0; i < n; i++) d.add(impl.makeElement(i));
310			Iterator it = d.descendingIterator();
311			assertTrue(it.hasNext());
312			assertEquals(impl.makeElement(n - 1), it.next());
313			assertTrue(it.hasNext());
314			assertEquals(impl.makeElement(n - 2), it.next());
315			it.forEachRemaining((e) -> {});
316			it.remove();
317			assertEquals(n - 1, d.size());
318			for (int i = 1; i < n; i++)
319			assertTrue(d.contains(impl.makeElement(i)));
320			assertFalse(d.contains(impl.makeElement(0)));
321			}
322			}
323
324	jsr166	1.1	/**
325			* stream().forEach returns elements in the collection
326			*/
327	jsr166	1.3	public void testStreamForEach() throws Throwable {
328	jsr166	1.1	final Collection c = impl.emptyCollection();
329			final AtomicLong count = new AtomicLong(0L);
330			final Object x = impl.makeElement(1);
331			final Object y = impl.makeElement(2);
332			final ArrayList found = new ArrayList();
333			Consumer<Object> spy = (o) -> { found.add(o); };
334			c.stream().forEach(spy);
335			assertTrue(found.isEmpty());
336
337			assertTrue(c.add(x));
338			c.stream().forEach(spy);
339			assertEquals(Collections.singletonList(x), found);
340			found.clear();
341
342			assertTrue(c.add(y));
343			c.stream().forEach(spy);
344			assertEquals(2, found.size());
345			assertTrue(found.contains(x));
346			assertTrue(found.contains(y));
347			found.clear();
348
349			c.clear();
350			c.stream().forEach(spy);
351			assertTrue(found.isEmpty());
352			}
353
354	jsr166	1.3	public void testStreamForEachConcurrentStressTest() throws Throwable {
355			if (!impl.isConcurrent()) return;
356			final Collection c = impl.emptyCollection();
357			final long testDurationMillis = timeoutMillis();
358			final AtomicBoolean done = new AtomicBoolean(false);
359			final Object elt = impl.makeElement(1);
360			final Future<?> f1, f2;
361			final ExecutorService pool = Executors.newCachedThreadPool();
362			try (PoolCleaner cleaner = cleaner(pool, done)) {
363			final CountDownLatch threadsStarted = new CountDownLatch(2);
364			Runnable checkElt = () -> {
365			threadsStarted.countDown();
366			while (!done.get())
367			c.stream().forEach((x) -> { assertSame(x, elt); }); };
368			Runnable addRemove = () -> {
369			threadsStarted.countDown();
370			while (!done.get()) {
371			assertTrue(c.add(elt));
372			assertTrue(c.remove(elt));
373			}};
374			f1 = pool.submit(checkElt);
375			f2 = pool.submit(addRemove);
376			Thread.sleep(testDurationMillis);
377			}
378			assertNull(f1.get(0L, MILLISECONDS));
379			assertNull(f2.get(0L, MILLISECONDS));
380			}
381
382			/**
383			* collection.forEach returns elements in the collection
384			*/
385			public void testForEach() throws Throwable {
386			final Collection c = impl.emptyCollection();
387			final AtomicLong count = new AtomicLong(0L);
388			final Object x = impl.makeElement(1);
389			final Object y = impl.makeElement(2);
390			final ArrayList found = new ArrayList();
391			Consumer<Object> spy = (o) -> { found.add(o); };
392			c.forEach(spy);
393			assertTrue(found.isEmpty());
394
395			assertTrue(c.add(x));
396			c.forEach(spy);
397			assertEquals(Collections.singletonList(x), found);
398			found.clear();
399
400			assertTrue(c.add(y));
401			c.forEach(spy);
402			assertEquals(2, found.size());
403			assertTrue(found.contains(x));
404			assertTrue(found.contains(y));
405			found.clear();
406
407			c.clear();
408			c.forEach(spy);
409			assertTrue(found.isEmpty());
410			}
411
412	jsr166	1.1	public void testForEachConcurrentStressTest() throws Throwable {
413			if (!impl.isConcurrent()) return;
414			final Collection c = impl.emptyCollection();
415	jsr166	1.2	final long testDurationMillis = timeoutMillis();
416	jsr166	1.1	final AtomicBoolean done = new AtomicBoolean(false);
417			final Object elt = impl.makeElement(1);
418	jsr166	1.2	final Future<?> f1, f2;
419			final ExecutorService pool = Executors.newCachedThreadPool();
420			try (PoolCleaner cleaner = cleaner(pool, done)) {
421			final CountDownLatch threadsStarted = new CountDownLatch(2);
422			Runnable checkElt = () -> {
423			threadsStarted.countDown();
424			while (!done.get())
425	jsr166	1.3	c.forEach((x) -> { assertSame(x, elt); }); };
426	jsr166	1.2	Runnable addRemove = () -> {
427			threadsStarted.countDown();
428			while (!done.get()) {
429			assertTrue(c.add(elt));
430			assertTrue(c.remove(elt));
431			}};
432			f1 = pool.submit(checkElt);
433			f2 = pool.submit(addRemove);
434			Thread.sleep(testDurationMillis);
435			}
436			assertNull(f1.get(0L, MILLISECONDS));
437			assertNull(f2.get(0L, MILLISECONDS));
438	jsr166	1.1	}
439
440	jsr166	1.4	// public void testCollection8DebugFail() {
441			// fail(impl.klazz().getSimpleName());
442			// }
443	jsr166	1.1	}