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LinkedBlockingQueueTest.javaAPI DocAndroid 1.5 API30846Wed May 06 22:41:02 BST 2009tests.api.java.util.concurrent

LinkedBlockingQueueTest

public class LinkedBlockingQueueTest extends JSR166TestCase

Fields Summary
Constructors Summary
Methods Summary
public static voidmain(java.lang.String[] args)

        junit.textui.TestRunner.run (suite());
private java.util.concurrent.LinkedBlockingQueuepopulatedQueue(int n)
Create a queue of given size containing consecutive Integers 0 ... n.

        LinkedBlockingQueue q = new LinkedBlockingQueue(n);
        assertTrue(q.isEmpty());
        for(int i = 0; i < n; i++)
            assertTrue(q.offer(new Integer(i)));
        assertFalse(q.isEmpty());
        assertEquals(0, q.remainingCapacity());
        assertEquals(n, q.size());
        return q;
public static junit.framework.Testsuite()

        return new TestSuite(LinkedBlockingQueueTest.class);
public voidtestAdd()
add succeeds if not full; throws ISE if full

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
            for (int i = 0; i < SIZE; ++i) {
                assertTrue(q.add(new Integer(i)));
            }
            assertEquals(0, q.remainingCapacity());
            q.add(new Integer(SIZE));
        } catch (IllegalStateException success){
        }
public voidtestAddAll1()
addAll(null) throws NPE

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(1);
            q.addAll(null);
            shouldThrow();
        }
        catch (NullPointerException success) {}
public voidtestAddAll2()
addAll of a collection with null elements throws NPE

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
            Integer[] ints = new Integer[SIZE];
            q.addAll(Arrays.asList(ints));
            shouldThrow();
        }
        catch (NullPointerException success) {}
public voidtestAddAll3()
addAll of a collection with any null elements throws NPE after possibly adding some elements

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
            Integer[] ints = new Integer[SIZE];
            for (int i = 0; i < SIZE-1; ++i)
                ints[i] = new Integer(i);
            q.addAll(Arrays.asList(ints));
            shouldThrow();
        }
        catch (NullPointerException success) {}
public voidtestAddAll4()
addAll throws ISE if not enough room

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(1);
            Integer[] ints = new Integer[SIZE];
            for (int i = 0; i < SIZE; ++i)
                ints[i] = new Integer(i);
            q.addAll(Arrays.asList(ints));
            shouldThrow();
        }
        catch (IllegalStateException success) {}
public voidtestAddAll5()
Queue contains all elements, in traversal order, of successful addAll

        try {
            Integer[] empty = new Integer[0];
            Integer[] ints = new Integer[SIZE];
            for (int i = 0; i < SIZE; ++i)
                ints[i] = new Integer(i);
            LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
            assertFalse(q.addAll(Arrays.asList(empty)));
            assertTrue(q.addAll(Arrays.asList(ints)));
            for (int i = 0; i < SIZE; ++i)
                assertEquals(ints[i], q.poll());
        }
        finally {}
public voidtestAddAllSelf()
addAll(this) throws IAE

        try {
            LinkedBlockingQueue q = populatedQueue(SIZE);
            q.addAll(q);
            shouldThrow();
        }
        catch (IllegalArgumentException success) {}
public voidtestAddNull()
add(null) throws NPE

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(1);
            q.add(null);
            shouldThrow();
        } catch (NullPointerException success) { }
public voidtestBlockingPut()
put blocks interruptibly if full

        Thread t = new Thread(new Runnable() {
                public void run() {
                    int added = 0;
                    try {
                        LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
                        for (int i = 0; i < SIZE; ++i) {
                            q.put(new Integer(i));
                            ++added;
                        }
                        q.put(new Integer(SIZE));
                        threadShouldThrow();
                    } catch (InterruptedException ie){
                        threadAssertEquals(added, SIZE);
                    }   
                }});
        t.start();
        try { 
           Thread.sleep(SHORT_DELAY_MS); 
           t.interrupt();
           t.join();
        }
        catch (InterruptedException ie) {
            unexpectedException();
        }
public voidtestBlockingTake()
Take removes existing elements until empty, then blocks interruptibly

        Thread t = new Thread(new Runnable() {
                public void run() {
                    try {
                        LinkedBlockingQueue q = populatedQueue(SIZE);
                        for (int i = 0; i < SIZE; ++i) {
                            assertEquals(i, ((Integer)q.take()).intValue());
                        }
                        q.take();
                        threadShouldThrow();
                    } catch (InterruptedException success){
                    }   
                }});
        t.start();
        try { 
           Thread.sleep(SHORT_DELAY_MS); 
           t.interrupt();
           t.join();
        }
        catch (InterruptedException ie) {
            unexpectedException();
        }
public voidtestClear()
clear removes all elements

        LinkedBlockingQueue q = populatedQueue(SIZE);
        q.clear();
        assertTrue(q.isEmpty());
        assertEquals(0, q.size());
        assertEquals(SIZE, q.remainingCapacity());
        q.add(one);
        assertFalse(q.isEmpty());
        q.clear();
        assertTrue(q.isEmpty());
public voidtestConstructor1()
A new queue has the indicated capacity, or Integer.MAX_VALUE if none given

        assertEquals(SIZE, new LinkedBlockingQueue(SIZE).remainingCapacity());
        assertEquals(Integer.MAX_VALUE, new LinkedBlockingQueue().remainingCapacity());
public voidtestConstructor2()
Constructor throws IAE if capacity argument nonpositive

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(0);
            shouldThrow();
        }
        catch (IllegalArgumentException success) {}
public voidtestConstructor3()
Initializing from null Collection throws NPE

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(null);
            shouldThrow();
        }
        catch (NullPointerException success) {}
public voidtestConstructor4()
Initializing from Collection of null elements throws NPE

        try {
            Integer[] ints = new Integer[SIZE];
            LinkedBlockingQueue q = new LinkedBlockingQueue(Arrays.asList(ints));
            shouldThrow();
        }
        catch (NullPointerException success) {}
public voidtestConstructor5()
Initializing from Collection with some null elements throws NPE

        try {
            Integer[] ints = new Integer[SIZE];
            for (int i = 0; i < SIZE-1; ++i)
                ints[i] = new Integer(i);
            LinkedBlockingQueue q = new LinkedBlockingQueue(Arrays.asList(ints));
            shouldThrow();
        }
        catch (NullPointerException success) {}
public voidtestConstructor6()
Queue contains all elements of collection used to initialize

        try {
            Integer[] ints = new Integer[SIZE];
            for (int i = 0; i < SIZE; ++i)
                ints[i] = new Integer(i);
            LinkedBlockingQueue q = new LinkedBlockingQueue(Arrays.asList(ints));
            for (int i = 0; i < SIZE; ++i)
                assertEquals(ints[i], q.poll());
        }
        finally {}
public voidtestContains()
contains(x) reports true when elements added but not yet removed

        LinkedBlockingQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(q.contains(new Integer(i)));
            q.poll();
            assertFalse(q.contains(new Integer(i)));
        }
public voidtestContainsAll()
containsAll(c) is true when c contains a subset of elements

        LinkedBlockingQueue q = populatedQueue(SIZE);
        LinkedBlockingQueue p = new LinkedBlockingQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(q.containsAll(p));
            assertFalse(p.containsAll(q));
            p.add(new Integer(i));
        }
        assertTrue(p.containsAll(q));
public voidtestDrainTo()
drainTo(c) empties queue into another collection c

        LinkedBlockingQueue q = populatedQueue(SIZE);
        ArrayList l = new ArrayList();
        q.drainTo(l);
        assertEquals(q.size(), 0);
        assertEquals(l.size(), SIZE);
        for (int i = 0; i < SIZE; ++i) 
            assertEquals(l.get(i), new Integer(i));
public voidtestDrainToN()
drainTo(c, n) empties first max {n, size} elements of queue into c

        for (int i = 0; i < SIZE + 2; ++i) {
            LinkedBlockingQueue q = populatedQueue(SIZE);
            ArrayList l = new ArrayList();
            q.drainTo(l, i);
            int k = (i < SIZE)? i : SIZE;
            assertEquals(q.size(), SIZE-k);
            assertEquals(l.size(), k);
            for (int j = 0; j < k; ++j) 
                assertEquals(l.get(j), new Integer(j));
        }
public voidtestDrainToNull()
drainTo(null) throws NPE

        LinkedBlockingQueue q = populatedQueue(SIZE);
        try {
            q.drainTo(null);
            shouldThrow();
        } catch(NullPointerException success) {
        }
public voidtestDrainToNullN()
drainTo(null, n) throws NPE

        LinkedBlockingQueue q = populatedQueue(SIZE);
        try {
            q.drainTo(null, 0);
            shouldThrow();
        } catch(NullPointerException success) {
        }
public voidtestDrainToSelf()
drainTo(this) throws IAE

        LinkedBlockingQueue q = populatedQueue(SIZE);
        try {
            q.drainTo(q);
            shouldThrow();
        } catch(IllegalArgumentException success) {
        }
public voidtestDrainToSelfN()
drainTo(this, n) throws IAE

        LinkedBlockingQueue q = populatedQueue(SIZE);
        try {
            q.drainTo(q, 0);
            shouldThrow();
        } catch(IllegalArgumentException success) {
        }
public voidtestDrainToWithActivePut()
drainTo empties full queue, unblocking a waiting put.

        final LinkedBlockingQueue q = populatedQueue(SIZE);
        Thread t = new Thread(new Runnable() {
                public void run() {
                    try {
                        q.put(new Integer(SIZE+1));
                    } catch (InterruptedException ie){ 
                        threadUnexpectedException();
                    }
                }
            });
        try {
            t.start();
            ArrayList l = new ArrayList();
            q.drainTo(l);
            assertTrue(l.size() >= SIZE);
            for (int i = 0; i < SIZE; ++i) 
                assertEquals(l.get(i), new Integer(i));
            t.join();
            assertTrue(q.size() + l.size() >= SIZE);
        } catch(Exception e){
            unexpectedException();
        }
public voidtestElement()
element returns next element, or throws NSEE if empty

        LinkedBlockingQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, ((Integer)q.element()).intValue());
            q.poll();
        }
        try {
            q.element();
            shouldThrow();
        }
        catch (NoSuchElementException success) {}
public voidtestEmptyFull()
Queue transitions from empty to full when elements added

        LinkedBlockingQueue q = new LinkedBlockingQueue(2);
        assertTrue(q.isEmpty());
        assertEquals("should have room for 2", 2, q.remainingCapacity());
        q.add(one);
        assertFalse(q.isEmpty());
        q.add(two);
        assertFalse(q.isEmpty());
        assertEquals(0, q.remainingCapacity());
        assertFalse(q.offer(three));
public voidtestInterruptedTimedPoll()
Interrupted timed poll throws InterruptedException instead of returning timeout status

        Thread t = new Thread(new Runnable() {
                public void run() {
                    try {
                        LinkedBlockingQueue q = populatedQueue(SIZE);
                        for (int i = 0; i < SIZE; ++i) {
                            threadAssertEquals(i, ((Integer)q.poll(SHORT_DELAY_MS, TimeUnit.MILLISECONDS)).intValue());
                        }
                        threadAssertNull(q.poll(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
                    } catch (InterruptedException success){
                    }   
                }});
        t.start();
        try { 
           Thread.sleep(SHORT_DELAY_MS); 
           t.interrupt();
           t.join();
        }
        catch (InterruptedException ie) {
            unexpectedException();
        }
public voidtestIterator()
iterator iterates through all elements

        LinkedBlockingQueue q = populatedQueue(SIZE);
        Iterator it = q.iterator();
        try {
            while(it.hasNext()){
                assertEquals(it.next(), q.take());
            }
        } catch (InterruptedException e){
            unexpectedException();
        }
public voidtestIteratorOrdering()
iterator ordering is FIFO

        final LinkedBlockingQueue q = new LinkedBlockingQueue(3);
        q.add(one);
        q.add(two);
        q.add(three);
        assertEquals(0, q.remainingCapacity());
        int k = 0;
        for (Iterator it = q.iterator(); it.hasNext();) {
            int i = ((Integer)(it.next())).intValue();
            assertEquals(++k, i);
        }
        assertEquals(3, k);
public voidtestIteratorRemove()
iterator.remove removes current element

        final LinkedBlockingQueue q = new LinkedBlockingQueue(3);
        q.add(two);
        q.add(one);
        q.add(three);

        Iterator it = q.iterator();
        it.next();
        it.remove();
        
        it = q.iterator();
        assertEquals(it.next(), one);
        assertEquals(it.next(), three);
        assertFalse(it.hasNext());
public voidtestOffer()
Offer succeeds if not full; fails if full

        LinkedBlockingQueue q = new LinkedBlockingQueue(1);
        assertTrue(q.offer(zero));
        assertFalse(q.offer(one));
public voidtestOfferInExecutor()
offer transfers elements across Executor tasks

        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
        q.add(one);
        q.add(two);
        ExecutorService executor = Executors.newFixedThreadPool(2);
        executor.execute(new Runnable() {
            public void run() {
                threadAssertFalse(q.offer(three));
                try {
                    threadAssertTrue(q.offer(three, MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS));
                    threadAssertEquals(0, q.remainingCapacity());
                }
                catch (InterruptedException e) {
                    threadUnexpectedException();
                }
            }
        });

        executor.execute(new Runnable() {
            public void run() {
                try {
                    Thread.sleep(SMALL_DELAY_MS);
                    threadAssertEquals(one, q.take());
                }
                catch (InterruptedException e) {
                    threadUnexpectedException();
                }
            }
        });
        
        joinPool(executor);
public voidtestOfferNull()
offer(null) throws NPE

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(1);
            q.offer(null);
            shouldThrow();
        } catch (NullPointerException success) { }
public voidtestPeek()
peek returns next element, or null if empty

        LinkedBlockingQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, ((Integer)q.peek()).intValue());
            q.poll();
            assertTrue(q.peek() == null ||
                       i != ((Integer)q.peek()).intValue());
        }
        assertNull(q.peek());
public voidtestPoll()
poll succeeds unless empty

        LinkedBlockingQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, ((Integer)q.poll()).intValue());
        }
        assertNull(q.poll());
public voidtestPollInExecutor()
poll retrieves elements across Executor threads

        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
        ExecutorService executor = Executors.newFixedThreadPool(2);
        executor.execute(new Runnable() {
            public void run() {
                threadAssertNull(q.poll());
                try {
                    threadAssertTrue(null != q.poll(MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS));
                    threadAssertTrue(q.isEmpty());
                }
                catch (InterruptedException e) {
                    threadUnexpectedException();
                }
            }
        });

        executor.execute(new Runnable() {
            public void run() {
                try {
                    Thread.sleep(SMALL_DELAY_MS);
                    q.put(one);
                }
                catch (InterruptedException e) {
                    threadUnexpectedException();
                }
            }
        });
        
        joinPool(executor);
public voidtestPut()
all elements successfully put are contained

         try {
             LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
             for (int i = 0; i < SIZE; ++i) {
                 Integer I = new Integer(i);
                 q.put(I);
                 assertTrue(q.contains(I));
             }
             assertEquals(0, q.remainingCapacity());
         }
        catch (InterruptedException ie) {
            unexpectedException();
        }
public voidtestPutNull()
put(null) throws NPE

        try {
            LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
            q.put(null);
            shouldThrow();
        } 
        catch (NullPointerException success){
        }   
        catch (InterruptedException ie) {
            unexpectedException();
        }
public voidtestPutWithTake()
put blocks waiting for take when full

        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
        Thread t = new Thread(new Runnable() {
                public void run() {
                    int added = 0;
                    try {
                        q.put(new Object());
                        ++added;
                        q.put(new Object());
                        ++added;
                        q.put(new Object());
                        ++added;
                        q.put(new Object());
                        ++added;
                        threadShouldThrow();
                    } catch (InterruptedException e){
                        threadAssertTrue(added >= 2);
                    }
                }
            });
        try {
            t.start();
            Thread.sleep(SHORT_DELAY_MS);
            q.take();
            t.interrupt();
            t.join();
        } catch (Exception e){
            unexpectedException();
        }
public voidtestRemainingCapacity()
remainingCapacity decreases on add, increases on remove

        LinkedBlockingQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.remainingCapacity());
            assertEquals(SIZE-i, q.size());
            q.remove();
        }
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(SIZE-i, q.remainingCapacity());
            assertEquals(i, q.size());
            q.add(new Integer(i));
        }
public voidtestRemove()
remove removes next element, or throws NSEE if empty

        LinkedBlockingQueue q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, ((Integer)q.remove()).intValue());
        }
        try {
            q.remove();
            shouldThrow();
        } catch (NoSuchElementException success){
        }
public voidtestRemoveAll()
removeAll(c) removes only those elements of c and reports true if changed

        for (int i = 1; i < SIZE; ++i) {
            LinkedBlockingQueue q = populatedQueue(SIZE);
            LinkedBlockingQueue p = populatedQueue(i);
            assertTrue(q.removeAll(p));
            assertEquals(SIZE-i, q.size());
            for (int j = 0; j < i; ++j) {
                Integer I = (Integer)(p.remove());
                assertFalse(q.contains(I));
            }
        }
public voidtestRemoveElement()
remove(x) removes x and returns true if present

        LinkedBlockingQueue q = populatedQueue(SIZE);
        for (int i = 1; i < SIZE; i+=2) {
            assertTrue(q.remove(new Integer(i)));
        }
        for (int i = 0; i < SIZE; i+=2) {
            assertTrue(q.remove(new Integer(i)));
            assertFalse(q.remove(new Integer(i+1)));
        }
        assertTrue(q.isEmpty());
public voidtestRetainAll()
retainAll(c) retains only those elements of c and reports true if changed

        LinkedBlockingQueue q = populatedQueue(SIZE);
        LinkedBlockingQueue p = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            boolean changed = q.retainAll(p);
            if (i == 0)
                assertFalse(changed);
            else
                assertTrue(changed);

            assertTrue(q.containsAll(p));
            assertEquals(SIZE-i, q.size());
            p.remove();
        }
public voidtestSerialization()
A deserialized serialized queue has same elements in same order

        LinkedBlockingQueue q = populatedQueue(SIZE);

        try {
            ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
            ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
            out.writeObject(q);
            out.close();

            ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
            ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin));
            LinkedBlockingQueue r = (LinkedBlockingQueue)in.readObject();
            assertEquals(q.size(), r.size());
            while (!q.isEmpty()) 
                assertEquals(q.remove(), r.remove());
        } catch(Exception e){
            unexpectedException();
        }
public voidtestTake()
take retrieves elements in FIFO order

        try {
            LinkedBlockingQueue q = populatedQueue(SIZE);
            for (int i = 0; i < SIZE; ++i) {
                assertEquals(i, ((Integer)q.take()).intValue());
            }
        } catch (InterruptedException e){
            unexpectedException();
        }
public voidtestTakeFromEmpty()
take blocks interruptibly when empty

        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
        Thread t = new Thread(new Runnable() {
                public void run() {
                    try {
                        q.take();
                        threadShouldThrow();
                    } catch (InterruptedException success){ }                
                }
            });
        try {
            t.start();
            Thread.sleep(SHORT_DELAY_MS);
            t.interrupt();
            t.join();
        } catch (Exception e){
            unexpectedException();
        }
public voidtestTimedOffer()
timed offer times out if full and elements not taken

        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
        Thread t = new Thread(new Runnable() {
                public void run() {
                    try {
                        q.put(new Object());
                        q.put(new Object());
                        threadAssertFalse(q.offer(new Object(), SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
                        q.offer(new Object(), LONG_DELAY_MS, TimeUnit.MILLISECONDS);
                        threadShouldThrow();
                    } catch (InterruptedException success){}
                }
            });
        
        try {
            t.start();
            Thread.sleep(SMALL_DELAY_MS);
            t.interrupt();
            t.join();
        } catch (Exception e){
            unexpectedException();
        }
public voidtestTimedPoll()
timed pool with nonzero timeout succeeds when non-empty, else times out

        try {
            LinkedBlockingQueue q = populatedQueue(SIZE);
            for (int i = 0; i < SIZE; ++i) {
                assertEquals(i, ((Integer)q.poll(SHORT_DELAY_MS, TimeUnit.MILLISECONDS)).intValue());
            }
            assertNull(q.poll(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
        } catch (InterruptedException e){
            unexpectedException();
        }
public voidtestTimedPoll0()
timed pool with zero timeout succeeds when non-empty, else times out

        try {
            LinkedBlockingQueue q = populatedQueue(SIZE);
            for (int i = 0; i < SIZE; ++i) {
                assertEquals(i, ((Integer)q.poll(0, TimeUnit.MILLISECONDS)).intValue());
            }
            assertNull(q.poll(0, TimeUnit.MILLISECONDS));
        } catch (InterruptedException e){
            unexpectedException();
        }
public voidtestTimedPollWithOffer()
timed poll before a delayed offer fails; after offer succeeds; on interruption throws

        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
        Thread t = new Thread(new Runnable() {
                public void run() {
                    try {
                        threadAssertNull(q.poll(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
                        q.poll(LONG_DELAY_MS, TimeUnit.MILLISECONDS);
                        q.poll(LONG_DELAY_MS, TimeUnit.MILLISECONDS);
                        threadShouldThrow();
                    } catch (InterruptedException success) { }                
                }
            });
        try {
            t.start();
            Thread.sleep(SMALL_DELAY_MS);
            assertTrue(q.offer(zero, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
            t.interrupt();
            t.join();
        } catch (Exception e){
            unexpectedException();
        }
public voidtestToArray()
toArray contains all elements

        LinkedBlockingQueue q = populatedQueue(SIZE);
        Object[] o = q.toArray();
        try {
        for(int i = 0; i < o.length; i++)
            assertEquals(o[i], q.take());
        } catch (InterruptedException e){
            unexpectedException();
        }
public voidtestToArray1_BadArg()
toArray with incompatible array type throws CCE

        try {
            LinkedBlockingQueue q = populatedQueue(SIZE);
            Object o[] = q.toArray(new String[10] );
            shouldThrow();
        } catch(ArrayStoreException  success){}
public voidtestToArray2()
toArray(a) contains all elements

        LinkedBlockingQueue q = populatedQueue(SIZE);
        Integer[] ints = new Integer[SIZE];
        ints = (Integer[])q.toArray(ints);
        try {
            for(int i = 0; i < ints.length; i++)
                assertEquals(ints[i], q.take());
        } catch (InterruptedException e){
            unexpectedException();
        }
public voidtestToArray_BadArg()
toArray(null) throws NPE

        try {
            LinkedBlockingQueue q = populatedQueue(SIZE);
            Object o[] = q.toArray(null);
            shouldThrow();
        } catch(NullPointerException success){}
public voidtestToString()
toString contains toStrings of elements

        LinkedBlockingQueue q = populatedQueue(SIZE);
        String s = q.toString();
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(s.indexOf(String.valueOf(i)) >= 0);
        }
public voidtestWeaklyConsistentIteration()
Modifications do not cause iterators to fail

        final LinkedBlockingQueue q = new LinkedBlockingQueue(3);
        q.add(one);
        q.add(two);
        q.add(three);
        try {
            for (Iterator it = q.iterator(); it.hasNext();) {
                q.remove();
                it.next();
            }
        }
        catch (ConcurrentModificationException e) {
            unexpectedException();
        }
        assertEquals(0, q.size());