--- jsr166/src/test/tck/LinkedBlockingQueueTest.java	2010/10/28 17:57:26	1.32
+++ jsr166/src/test/tck/LinkedBlockingQueueTest.java	2021/01/27 01:57:24	1.83
@@ -1,16 +1,26 @@
 /*
  * Written by Doug Lea with assistance from members of JCP JSR-166
  * Expert Group and released to the public domain, as explained at
- * http://creativecommons.org/licenses/publicdomain
+ * http://creativecommons.org/publicdomain/zero/1.0/
  * Other contributors include Andrew Wright, Jeffrey Hayes,
  * Pat Fisher, Mike Judd.
  */
 
-import junit.framework.*;
-import java.util.*;
-import java.util.concurrent.*;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
-import java.io.*;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.Queue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import junit.framework.Test;
 
 public class LinkedBlockingQueueTest extends JSR166TestCase {
 
@@ -22,33 +32,41 @@ public class LinkedBlockingQueueTest ext
 
     public static class Bounded extends BlockingQueueTest {
         protected BlockingQueue emptyCollection() {
-            return new LinkedBlockingQueue(20);
+            return new LinkedBlockingQueue(SIZE);
         }
     }
 
     public static void main(String[] args) {
-        junit.textui.TestRunner.run(suite());
+        main(suite(), args);
     }
 
     public static Test suite() {
+        class Implementation implements CollectionImplementation {
+            public Class<?> klazz() { return LinkedBlockingQueue.class; }
+            public Collection emptyCollection() { return new LinkedBlockingQueue(); }
+            public Object makeElement(int i) { return JSR166TestCase.itemFor(i); }
+            public boolean isConcurrent() { return true; }
+            public boolean permitsNulls() { return false; }
+        }
         return newTestSuite(LinkedBlockingQueueTest.class,
                             new Unbounded().testSuite(),
-                            new Bounded().testSuite());
+                            new Bounded().testSuite(),
+                            CollectionTest.testSuite(new Implementation()));
     }
 
-
     /**
-     * Create a queue of given size containing consecutive
-     * Integers 0 ... n.
+     * Returns a new queue of given size containing consecutive
+     * Items 0 ... n - 1.
      */
-    private LinkedBlockingQueue populatedQueue(int n) {
-        LinkedBlockingQueue q = new LinkedBlockingQueue(n);
+    private static LinkedBlockingQueue<Item> populatedQueue(int n) {
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(n);
         assertTrue(q.isEmpty());
         for (int i = 0; i < n; i++)
-            assertTrue(q.offer(new Integer(i)));
+            mustOffer(q, i);
         assertFalse(q.isEmpty());
-        assertEquals(0, q.remainingCapacity());
-        assertEquals(n, q.size());
+        mustEqual(0, q.remainingCapacity());
+        mustEqual(n, q.size());
+        mustEqual(0, q.peek());
         return q;
     }
 
@@ -57,50 +75,51 @@ public class LinkedBlockingQueueTest ext
      * none given
      */
     public void testConstructor1() {
-        assertEquals(SIZE, new LinkedBlockingQueue(SIZE).remainingCapacity());
-        assertEquals(Integer.MAX_VALUE, new LinkedBlockingQueue().remainingCapacity());
+        mustEqual(SIZE, new LinkedBlockingQueue<Item>(SIZE).remainingCapacity());
+        mustEqual(Integer.MAX_VALUE, new LinkedBlockingQueue<Item>().remainingCapacity());
     }
 
     /**
-     * Constructor throws IAE if capacity argument nonpositive
+     * Constructor throws IllegalArgumentException if capacity argument nonpositive
      */
     public void testConstructor2() {
         try {
-            LinkedBlockingQueue q = new LinkedBlockingQueue(0);
+            new LinkedBlockingQueue<Item>(0);
             shouldThrow();
         } catch (IllegalArgumentException success) {}
     }
 
     /**
-     * Initializing from null Collection throws NPE
+     * Initializing from null Collection throws NullPointerException
      */
     public void testConstructor3() {
         try {
-            LinkedBlockingQueue q = new LinkedBlockingQueue(null);
+            new LinkedBlockingQueue<Item>(null);
             shouldThrow();
         } catch (NullPointerException success) {}
     }
 
     /**
-     * Initializing from Collection of null elements throws NPE
+     * Initializing from Collection of null elements throws NullPointerException
      */
     public void testConstructor4() {
+        Collection<Item> elements = Arrays.asList(new Item[SIZE]);
         try {
-            Integer[] ints = new Integer[SIZE];
-            LinkedBlockingQueue q = new LinkedBlockingQueue(Arrays.asList(ints));
+            new LinkedBlockingQueue<Item>(elements);
             shouldThrow();
         } catch (NullPointerException success) {}
     }
 
     /**
-     * Initializing from Collection with some null elements throws NPE
+     * Initializing from Collection with some null elements throws
+     * NullPointerException
      */
     public void testConstructor5() {
+        Item[] items = new Item[2];
+        items[0] = zero;
+        Collection<Item> elements = Arrays.asList(items);
         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));
+            new LinkedBlockingQueue<Item>(elements);
             shouldThrow();
         } catch (NullPointerException success) {}
     }
@@ -109,26 +128,24 @@ public class LinkedBlockingQueueTest ext
      * Queue contains all elements of collection used to initialize
      */
     public void testConstructor6() {
-        Integer[] ints = new Integer[SIZE];
-        for (int i = 0; i < SIZE; ++i)
-            ints[i] = new Integer(i);
-        LinkedBlockingQueue q = new LinkedBlockingQueue(Arrays.asList(ints));
+        Item[] items = defaultItems;
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(Arrays.asList(items));
         for (int i = 0; i < SIZE; ++i)
-            assertEquals(ints[i], q.poll());
+            mustEqual(items[i], q.poll());
     }
 
     /**
      * Queue transitions from empty to full when elements added
      */
     public void testEmptyFull() {
-        LinkedBlockingQueue q = new LinkedBlockingQueue(2);
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(2);
         assertTrue(q.isEmpty());
-        assertEquals("should have room for 2", 2, q.remainingCapacity());
+        mustEqual(2, q.remainingCapacity());
         q.add(one);
         assertFalse(q.isEmpty());
         q.add(two);
         assertFalse(q.isEmpty());
-        assertEquals(0, q.remainingCapacity());
+        mustEqual(0, q.remainingCapacity());
         assertFalse(q.offer(three));
     }
 
@@ -136,124 +153,76 @@ public class LinkedBlockingQueueTest ext
      * remainingCapacity decreases on add, increases on remove
      */
     public void testRemainingCapacity() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        BlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, q.remainingCapacity());
-            assertEquals(SIZE-i, q.size());
-            q.remove();
+            mustEqual(i, q.remainingCapacity());
+            mustEqual(SIZE, q.size() + q.remainingCapacity());
+            mustEqual(i, q.remove());
         }
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(SIZE-i, q.remainingCapacity());
-            assertEquals(i, q.size());
-            q.add(new Integer(i));
+            mustEqual(SIZE - i, q.remainingCapacity());
+            mustEqual(SIZE, q.size() + q.remainingCapacity());
+            mustAdd(q, i);
         }
     }
 
     /**
-     * offer(null) throws NPE
-     */
-    public void testOfferNull() {
-        try {
-            LinkedBlockingQueue q = new LinkedBlockingQueue(1);
-            q.offer(null);
-            shouldThrow();
-        } catch (NullPointerException success) {}
-    }
-
-    /**
-     * add(null) throws NPE
-     */
-    public void testAddNull() {
-        try {
-            LinkedBlockingQueue q = new LinkedBlockingQueue(1);
-            q.add(null);
-            shouldThrow();
-        } catch (NullPointerException success) {}
-    }
-
-    /**
      * Offer succeeds if not full; fails if full
      */
     public void testOffer() {
-        LinkedBlockingQueue q = new LinkedBlockingQueue(1);
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(1);
         assertTrue(q.offer(zero));
         assertFalse(q.offer(one));
     }
 
     /**
-     * add succeeds if not full; throws ISE if full
+     * add succeeds if not full; throws IllegalStateException if full
      */
     public void testAdd() {
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(SIZE);
+        for (int i = 0; i < SIZE; ++i)
+            mustAdd(q, i);
+        mustEqual(0, q.remainingCapacity());
         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));
+            q.add(new Item(SIZE));
             shouldThrow();
         } catch (IllegalStateException success) {}
     }
 
     /**
-     * addAll(null) throws NPE
-     */
-    public void testAddAll1() {
-        try {
-            LinkedBlockingQueue q = new LinkedBlockingQueue(1);
-            q.addAll(null);
-            shouldThrow();
-        } catch (NullPointerException success) {}
-    }
-
-    /**
-     * addAll(this) throws IAE
+     * addAll(this) throws IllegalArgumentException
      */
     public void testAddAllSelf() {
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         try {
-            LinkedBlockingQueue q = populatedQueue(SIZE);
             q.addAll(q);
             shouldThrow();
         } catch (IllegalArgumentException success) {}
     }
 
     /**
-     * addAll of a collection with null elements throws NPE
-     */
-    public void testAddAll2() {
-        try {
-            LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
-            Integer[] ints = new Integer[SIZE];
-            q.addAll(Arrays.asList(ints));
-            shouldThrow();
-        } catch (NullPointerException success) {}
-    }
-
-    /**
      * addAll of a collection with any null elements throws NPE after
      * possibly adding some elements
      */
     public void testAddAll3() {
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(SIZE);
+        Item[] items = new Item[2]; items[0] = zero;
+        Collection<Item> elements = Arrays.asList(items);
         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));
+            q.addAll(elements);
             shouldThrow();
         } catch (NullPointerException success) {}
     }
 
     /**
-     * addAll throws ISE if not enough room
+     * addAll throws IllegalStateException if not enough room
      */
     public void testAddAll4() {
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(SIZE - 1);
+        Item[] items = defaultItems;
+        Collection<Item> elements = Arrays.asList(items);
         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));
+            q.addAll(elements);
             shouldThrow();
         } catch (IllegalStateException success) {}
     }
@@ -262,121 +231,148 @@ public class LinkedBlockingQueueTest ext
      * Queue contains all elements, in traversal order, of successful addAll
      */
     public void testAddAll5() {
-        Integer[] empty = new Integer[0];
-        Integer[] ints = new Integer[SIZE];
-        for (int i = 0; i < SIZE; ++i)
-            ints[i] = new Integer(i);
-        LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
+        Item[] empty = new Item[0];
+        Item[] items = defaultItems;
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(SIZE);
         assertFalse(q.addAll(Arrays.asList(empty)));
-        assertTrue(q.addAll(Arrays.asList(ints)));
+        assertTrue(q.addAll(Arrays.asList(items)));
         for (int i = 0; i < SIZE; ++i)
-            assertEquals(ints[i], q.poll());
+            mustEqual(items[i], q.poll());
     }
 
     /**
-     * put(null) throws NPE
-     */
-     public void testPutNull() throws InterruptedException {
-        try {
-            LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
-            q.put(null);
-            shouldThrow();
-        } catch (NullPointerException success) {}
-     }
-
-    /**
      * all elements successfully put are contained
      */
     public void testPut() throws InterruptedException {
-        LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            Integer I = new Integer(i);
-            q.put(I);
-            assertTrue(q.contains(I));
+            Item x = itemFor(i);
+            q.put(x);
+            mustContain(q, x);
         }
-        assertEquals(0, q.remainingCapacity());
+        mustEqual(0, q.remainingCapacity());
     }
 
     /**
      * put blocks interruptibly if full
      */
     public void testBlockingPut() throws InterruptedException {
-        final LinkedBlockingQueue q = new LinkedBlockingQueue(SIZE);
-        Thread t = new Thread(new CheckedRunnable() {
+        final LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(SIZE);
+        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
+        Thread t = newStartedThread(new CheckedRunnable() {
             public void realRun() throws InterruptedException {
                 for (int i = 0; i < SIZE; ++i)
-                    q.put(i);
-                assertEquals(SIZE, q.size());
-                assertEquals(0, q.remainingCapacity());
+                    q.put(itemFor(i));
+                mustEqual(SIZE, q.size());
+                mustEqual(0, q.remainingCapacity());
+
+                Thread.currentThread().interrupt();
                 try {
-                    q.put(99);
+                    q.put(ninetynine);
                     shouldThrow();
                 } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
+
+                pleaseInterrupt.countDown();
+                try {
+                    q.put(ninetynine);
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
             }});
 
-        t.start();
-        Thread.sleep(SHORT_DELAY_MS);
+        await(pleaseInterrupt);
+        if (randomBoolean()) assertThreadBlocks(t, Thread.State.WAITING);
         t.interrupt();
-        t.join();
-        assertEquals(SIZE, q.size());
-        assertEquals(0, q.remainingCapacity());
+        awaitTermination(t);
+        mustEqual(SIZE, q.size());
+        mustEqual(0, q.remainingCapacity());
     }
 
     /**
-     * put blocks waiting for take when full
+     * put blocks interruptibly waiting for take when full
      */
     public void testPutWithTake() throws InterruptedException {
         final int capacity = 2;
-        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
-        Thread t = new Thread(new CheckedRunnable() {
+        final LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(2);
+        final CountDownLatch pleaseTake = new CountDownLatch(1);
+        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
+        Thread t = newStartedThread(new CheckedRunnable() {
             public void realRun() throws InterruptedException {
-                for (int i = 0; i < capacity + 1; i++)
-                    q.put(i);
+                for (int i = 0; i < capacity; i++)
+                    q.put(itemFor(i));
+                pleaseTake.countDown();
+                q.put(eightysix);
+
+                Thread.currentThread().interrupt();
                 try {
-                    q.put(99);
+                    q.put(ninetynine);
                     shouldThrow();
                 } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
+
+                pleaseInterrupt.countDown();
+                try {
+                    q.put(ninetynine);
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
             }});
 
-        t.start();
-        Thread.sleep(SHORT_DELAY_MS);
-        assertEquals(q.remainingCapacity(), 0);
-        assertEquals(0, q.take());
-        Thread.sleep(SHORT_DELAY_MS);
+        await(pleaseTake);
+        mustEqual(0, q.remainingCapacity());
+        mustEqual(0, q.take());
+
+        await(pleaseInterrupt);
+        if (randomBoolean()) assertThreadBlocks(t, Thread.State.WAITING);
         t.interrupt();
-        t.join();
-        assertEquals(q.remainingCapacity(), 0);
+        awaitTermination(t);
+        mustEqual(0, q.remainingCapacity());
     }
 
     /**
      * timed offer times out if full and elements not taken
      */
-    public void testTimedOffer() throws InterruptedException {
-        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
-        Thread t = new Thread(new CheckedRunnable() {
+    public void testTimedOffer() {
+        final LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(2);
+        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
+        Thread t = newStartedThread(new CheckedRunnable() {
             public void realRun() throws InterruptedException {
-                q.put(new Object());
-                q.put(new Object());
-                assertFalse(q.offer(new Object(), SHORT_DELAY_MS, MILLISECONDS));
+                q.put(zero);
+                q.put(one);
+                long startTime = System.nanoTime();
+
+                assertFalse(q.offer(two, timeoutMillis(), MILLISECONDS));
+                assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
+
+                Thread.currentThread().interrupt();
+                try {
+                    q.offer(three, randomTimeout(), randomTimeUnit());
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
+
+                pleaseInterrupt.countDown();
                 try {
-                    q.offer(new Object(), LONG_DELAY_MS, MILLISECONDS);
+                    q.offer(two, LONGER_DELAY_MS, MILLISECONDS);
                     shouldThrow();
                 } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
             }});
 
-        t.start();
-        Thread.sleep(SMALL_DELAY_MS);
+        await(pleaseInterrupt);
+        if (randomBoolean()) assertThreadBlocks(t, Thread.State.TIMED_WAITING);
         t.interrupt();
-        t.join();
+        awaitTermination(t);
     }
 
     /**
      * take retrieves elements in FIFO order
      */
     public void testTake() throws InterruptedException {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, q.take());
+            mustEqual(i, q.take());
         }
     }
 
@@ -384,55 +380,69 @@ public class LinkedBlockingQueueTest ext
      * Take removes existing elements until empty, then blocks interruptibly
      */
     public void testBlockingTake() throws InterruptedException {
-        final LinkedBlockingQueue q = populatedQueue(SIZE);
-        Thread t = new Thread(new CheckedRunnable() {
+        final BlockingQueue<Item> q = populatedQueue(SIZE);
+        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
+        Thread t = newStartedThread(new CheckedRunnable() {
             public void realRun() throws InterruptedException {
-                for (int i = 0; i < SIZE; ++i) {
-                    assertEquals(i, q.take());
-                }
+                for (int i = 0; i < SIZE; i++) mustEqual(i, q.take());
+
+                Thread.currentThread().interrupt();
+                try {
+                    q.take();
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
+
+                pleaseInterrupt.countDown();
                 try {
                     q.take();
                     shouldThrow();
                 } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
             }});
 
-        t.start();
-        Thread.sleep(SHORT_DELAY_MS);
+        await(pleaseInterrupt);
+        if (randomBoolean()) assertThreadBlocks(t, Thread.State.WAITING);
         t.interrupt();
-        t.join();
+        awaitTermination(t);
     }
 
     /**
      * poll succeeds unless empty
      */
     public void testPoll() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, q.poll());
+            mustEqual(i, q.poll());
         }
         assertNull(q.poll());
     }
 
     /**
-     * timed pool with zero timeout succeeds when non-empty, else times out
+     * timed poll with zero timeout succeeds when non-empty, else times out
      */
     public void testTimedPoll0() throws InterruptedException {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, q.poll(0, MILLISECONDS));
+            mustEqual(i, q.poll(0, MILLISECONDS));
         }
         assertNull(q.poll(0, MILLISECONDS));
     }
 
     /**
-     * timed pool with nonzero timeout succeeds when non-empty, else times out
+     * timed poll with nonzero timeout succeeds when non-empty, else times out
      */
     public void testTimedPoll() throws InterruptedException {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, q.poll(SHORT_DELAY_MS, MILLISECONDS));
-        }
-        assertNull(q.poll(SHORT_DELAY_MS, MILLISECONDS));
+            long startTime = System.nanoTime();
+            mustEqual(i, q.poll(LONG_DELAY_MS, MILLISECONDS));
+            assertTrue(millisElapsedSince(startTime) < LONG_DELAY_MS);
+        }
+        long startTime = System.nanoTime();
+        assertNull(q.poll(timeoutMillis(), MILLISECONDS));
+        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
+        checkEmpty(q);
     }
 
     /**
@@ -440,32 +450,43 @@ public class LinkedBlockingQueueTest ext
      * returning timeout status
      */
     public void testInterruptedTimedPoll() throws InterruptedException {
-        Thread t = new Thread(new CheckedRunnable() {
+        final BlockingQueue<Item> q = populatedQueue(SIZE);
+        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
+        Thread t = newStartedThread(new CheckedRunnable() {
             public void realRun() throws InterruptedException {
-                LinkedBlockingQueue q = populatedQueue(SIZE);
-                for (int i = 0; i < SIZE; ++i) {
-                    assertEquals(i, q.poll(SHORT_DELAY_MS, MILLISECONDS));
-                }
+                for (int i = 0; i < SIZE; i++)
+                    mustEqual(i, q.poll(LONG_DELAY_MS, MILLISECONDS));
+
+                Thread.currentThread().interrupt();
+                try {
+                    q.poll(randomTimeout(), randomTimeUnit());
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
+
+                pleaseInterrupt.countDown();
                 try {
-                    q.poll(SMALL_DELAY_MS, MILLISECONDS);
+                    q.poll(LONGER_DELAY_MS, MILLISECONDS);
                     shouldThrow();
                 } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
             }});
 
-        t.start();
-        Thread.sleep(SHORT_DELAY_MS);
+        await(pleaseInterrupt);
+        if (randomBoolean()) assertThreadBlocks(t, Thread.State.TIMED_WAITING);
         t.interrupt();
-        t.join();
+        awaitTermination(t);
+        checkEmpty(q);
     }
 
     /**
      * peek returns next element, or null if empty
      */
     public void testPeek() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, q.peek());
-            assertEquals(i, q.poll());
+            mustEqual(i, q.peek());
+            mustEqual(i, q.poll());
             assertTrue(q.peek() == null ||
                        !q.peek().equals(i));
         }
@@ -476,10 +497,10 @@ public class LinkedBlockingQueueTest ext
      * element returns next element, or throws NSEE if empty
      */
     public void testElement() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, q.element());
-            assertEquals(i, q.poll());
+            mustEqual(i, q.element());
+            mustEqual(i, q.poll());
         }
         try {
             q.element();
@@ -491,9 +512,9 @@ public class LinkedBlockingQueueTest ext
      * remove removes next element, or throws NSEE if empty
      */
     public void testRemove() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, q.remove());
+            mustEqual(i, q.remove());
         }
         try {
             q.remove();
@@ -502,42 +523,27 @@ public class LinkedBlockingQueueTest ext
     }
 
     /**
-     * remove(x) removes x and returns true if present
-     */
-    public void testRemoveElement() {
-        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());
-    }
-
-    /**
      * An add following remove(x) succeeds
      */
     public void testRemoveElementAndAdd() throws InterruptedException {
-        LinkedBlockingQueue q = new LinkedBlockingQueue();
-        assertTrue(q.add(new Integer(1)));
-        assertTrue(q.add(new Integer(2)));
-        assertTrue(q.remove(new Integer(1)));
-        assertTrue(q.remove(new Integer(2)));
-        assertTrue(q.add(new Integer(3)));
-        assertTrue(q.take() != null);
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>();
+        assertTrue(q.add(one));
+        assertTrue(q.add(two));
+        mustRemove(q, one);
+        mustRemove(q, two);
+        mustAdd(q, three);
+        assertNotNull(q.take());
     }
 
     /**
      * contains(x) reports true when elements added but not yet removed
      */
     public void testContains() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertTrue(q.contains(new Integer(i)));
+            mustContain(q, i);
             q.poll();
-            assertFalse(q.contains(new Integer(i)));
+            mustNotContain(q, i);
         }
     }
 
@@ -545,11 +551,11 @@ public class LinkedBlockingQueueTest ext
      * clear removes all elements
      */
     public void testClear() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         q.clear();
         assertTrue(q.isEmpty());
-        assertEquals(0, q.size());
-        assertEquals(SIZE, q.remainingCapacity());
+        mustEqual(0, q.size());
+        mustEqual(SIZE, q.remainingCapacity());
         q.add(one);
         assertFalse(q.isEmpty());
         assertTrue(q.contains(one));
@@ -561,12 +567,12 @@ public class LinkedBlockingQueueTest ext
      * containsAll(c) is true when c contains a subset of elements
      */
     public void testContainsAll() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        LinkedBlockingQueue p = new LinkedBlockingQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> p = new LinkedBlockingQueue<>(SIZE);
         for (int i = 0; i < SIZE; ++i) {
             assertTrue(q.containsAll(p));
             assertFalse(p.containsAll(q));
-            p.add(new Integer(i));
+            mustAdd(p, i);
         }
         assertTrue(p.containsAll(q));
     }
@@ -575,8 +581,8 @@ public class LinkedBlockingQueueTest ext
      * retainAll(c) retains only those elements of c and reports true if changed
      */
     public void testRetainAll() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        LinkedBlockingQueue p = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> p = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
             boolean changed = q.retainAll(p);
             if (i == 0)
@@ -585,7 +591,7 @@ public class LinkedBlockingQueueTest ext
                 assertTrue(changed);
 
             assertTrue(q.containsAll(p));
-            assertEquals(SIZE-i, q.size());
+            mustEqual(SIZE - i, q.size());
             p.remove();
         }
     }
@@ -595,82 +601,88 @@ public class LinkedBlockingQueueTest ext
      */
     public void testRemoveAll() {
         for (int i = 1; i < SIZE; ++i) {
-            LinkedBlockingQueue q = populatedQueue(SIZE);
-            LinkedBlockingQueue p = populatedQueue(i);
+            LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
+            LinkedBlockingQueue<Item> p = populatedQueue(i);
             assertTrue(q.removeAll(p));
-            assertEquals(SIZE-i, q.size());
+            mustEqual(SIZE - i, q.size());
             for (int j = 0; j < i; ++j) {
-                Integer I = (Integer)(p.remove());
-                assertFalse(q.contains(I));
+                mustNotContain(q, p.remove());
             }
         }
     }
 
     /**
-     * toArray contains all elements
+     * toArray contains all elements in FIFO order
      */
-    public void testToArray() throws InterruptedException {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        Object[] o = q.toArray();
-        for (int i = 0; i < o.length; i++)
-            assertEquals(o[i], q.take());
+    public void testToArray() {
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
+        Object[] a = q.toArray();
+        assertSame(Object[].class, a.getClass());
+        for (Object o : a)
+            assertSame(o, q.poll());
+        assertTrue(q.isEmpty());
     }
 
     /**
-     * toArray(a) contains all elements
+     * toArray(a) contains all elements in FIFO order
      */
     public void testToArray2() throws InterruptedException {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        Integer[] ints = new Integer[SIZE];
-        ints = (Integer[])q.toArray(ints);
-        for (int i = 0; i < ints.length; i++)
-            assertEquals(ints[i], q.take());
-    }
-
-    /**
-     * toArray(null) throws NPE
-     */
-    public void testToArray_BadArg() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        try {
-            Object o[] = q.toArray(null);
-            shouldThrow();
-        } catch (NullPointerException success) {}
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
+        Item[] items = new Item[SIZE];
+        Item[] array = q.toArray(items);
+        assertSame(items, array);
+        for (Item o : items)
+            assertSame(o, q.poll());
+        assertTrue(q.isEmpty());
     }
 
     /**
-     * toArray with incompatible array type throws CCE
+     * toArray(incompatible array type) throws ArrayStoreException
      */
     public void testToArray1_BadArg() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         try {
-            Object o[] = q.toArray(new String[10]);
+            q.toArray(new String[10]);
             shouldThrow();
         } catch (ArrayStoreException success) {}
     }
 
-
     /**
      * iterator iterates through all elements
      */
     public void testIterator() throws InterruptedException {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        Iterator it = q.iterator();
-        while (it.hasNext()) {
-            assertEquals(it.next(), q.take());
-        }
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
+        Iterator<? extends Item> it = q.iterator();
+        int i;
+        for (i = 0; it.hasNext(); i++)
+            mustContain(q, it.next());
+        mustEqual(i, SIZE);
+        assertIteratorExhausted(it);
+
+        it = q.iterator();
+        for (i = 0; it.hasNext(); i++)
+            mustEqual(it.next(), q.take());
+        mustEqual(i, SIZE);
+        assertIteratorExhausted(it);
+    }
+
+    /**
+     * iterator of empty collection has no elements
+     */
+    public void testEmptyIterator() {
+        assertIteratorExhausted(new LinkedBlockingQueue<Item>().iterator());
     }
 
     /**
      * iterator.remove removes current element
      */
     public void testIteratorRemove() {
-        final LinkedBlockingQueue q = new LinkedBlockingQueue(3);
+        final LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(3);
         q.add(two);
         q.add(one);
         q.add(three);
 
-        Iterator it = q.iterator();
+        Iterator<? extends Item> it = q.iterator();
         it.next();
         it.remove();
 
@@ -680,220 +692,191 @@ public class LinkedBlockingQueueTest ext
         assertFalse(it.hasNext());
     }
 
-
     /**
      * iterator ordering is FIFO
      */
     public void testIteratorOrdering() {
-        final LinkedBlockingQueue q = new LinkedBlockingQueue(3);
+        final LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(3);
         q.add(one);
         q.add(two);
         q.add(three);
-        assertEquals(0, q.remainingCapacity());
+        mustEqual(0, q.remainingCapacity());
         int k = 0;
-        for (Iterator it = q.iterator(); it.hasNext();) {
-            assertEquals(++k, it.next());
+        for (Iterator<? extends Item> it = q.iterator(); it.hasNext();) {
+            mustEqual(++k, it.next());
         }
-        assertEquals(3, k);
+        mustEqual(3, k);
     }
 
     /**
      * Modifications do not cause iterators to fail
      */
     public void testWeaklyConsistentIteration() {
-        final LinkedBlockingQueue q = new LinkedBlockingQueue(3);
+        final LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(3);
         q.add(one);
         q.add(two);
         q.add(three);
-        for (Iterator it = q.iterator(); it.hasNext();) {
+        for (Iterator<? extends Item> it = q.iterator(); it.hasNext();) {
             q.remove();
             it.next();
         }
-        assertEquals(0, q.size());
+        mustEqual(0, q.size());
     }
 
-
     /**
      * toString contains toStrings of elements
      */
     public void testToString() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         String s = q.toString();
         for (int i = 0; i < SIZE; ++i) {
-            assertTrue(s.indexOf(String.valueOf(i)) >= 0);
+            assertTrue(s.contains(String.valueOf(i)));
         }
     }
 
-
     /**
      * offer transfers elements across Executor tasks
      */
     public void testOfferInExecutor() {
-        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
+        final LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(2);
         q.add(one);
         q.add(two);
-        ExecutorService executor = Executors.newFixedThreadPool(2);
-        executor.execute(new CheckedRunnable() {
-            public void realRun() throws InterruptedException {
-                assertFalse(q.offer(three));
-                assertTrue(q.offer(three, MEDIUM_DELAY_MS, MILLISECONDS));
-                assertEquals(0, q.remainingCapacity());
-            }});
-
-        executor.execute(new CheckedRunnable() {
-            public void realRun() throws InterruptedException {
-                Thread.sleep(SMALL_DELAY_MS);
-                assertSame(one, q.take());
-            }});
-
-        joinPool(executor);
+        final CheckedBarrier threadsStarted = new CheckedBarrier(2);
+        final ExecutorService executor = Executors.newFixedThreadPool(2);
+        try (PoolCleaner cleaner = cleaner(executor)) {
+            executor.execute(new CheckedRunnable() {
+                public void realRun() throws InterruptedException {
+                    assertFalse(q.offer(three));
+                    threadsStarted.await();
+                    assertTrue(q.offer(three, LONG_DELAY_MS, MILLISECONDS));
+                    mustEqual(0, q.remainingCapacity());
+                }});
+
+            executor.execute(new CheckedRunnable() {
+                public void realRun() throws InterruptedException {
+                    threadsStarted.await();
+                    assertSame(one, q.take());
+                }});
+        }
     }
 
     /**
-     * poll retrieves elements across Executor threads
+     * timed poll retrieves elements across Executor threads
      */
     public void testPollInExecutor() {
-        final LinkedBlockingQueue q = new LinkedBlockingQueue(2);
-        ExecutorService executor = Executors.newFixedThreadPool(2);
-        executor.execute(new CheckedRunnable() {
-            public void realRun() throws InterruptedException {
-                assertNull(q.poll());
-                assertSame(one, q.poll(MEDIUM_DELAY_MS, MILLISECONDS));
-                assertTrue(q.isEmpty());
-            }});
-
-        executor.execute(new CheckedRunnable() {
-            public void realRun() throws InterruptedException {
-                Thread.sleep(SMALL_DELAY_MS);
-                q.put(one);
-            }});
-
-        joinPool(executor);
+        final LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>(2);
+        final CheckedBarrier threadsStarted = new CheckedBarrier(2);
+        final ExecutorService executor = Executors.newFixedThreadPool(2);
+        try (PoolCleaner cleaner = cleaner(executor)) {
+            executor.execute(new CheckedRunnable() {
+                public void realRun() throws InterruptedException {
+                    assertNull(q.poll());
+                    threadsStarted.await();
+                    assertSame(one, q.poll(LONG_DELAY_MS, MILLISECONDS));
+                    checkEmpty(q);
+                }});
+
+            executor.execute(new CheckedRunnable() {
+                public void realRun() throws InterruptedException {
+                    threadsStarted.await();
+                    q.put(one);
+                }});
+        }
     }
 
     /**
-     * A deserialized serialized queue has same elements in same order
+     * A deserialized/reserialized queue has same elements in same order
      */
     public void testSerialization() throws Exception {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-
-        ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
-        ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
-        out.writeObject(q);
-        out.close();
+        Queue<Item> x = populatedQueue(SIZE);
+        Queue<Item> y = serialClone(x);
 
-        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());
-    }
-
-    /**
-     * drainTo(null) throws NPE
-     */
-    public void testDrainToNull() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        try {
-            q.drainTo(null);
-            shouldThrow();
-        } catch (NullPointerException success) {}
-    }
-
-    /**
-     * drainTo(this) throws IAE
-     */
-    public void testDrainToSelf() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        try {
-            q.drainTo(q);
-            shouldThrow();
-        } catch (IllegalArgumentException success) {}
+        assertNotSame(x, y);
+        mustEqual(x.size(), y.size());
+        mustEqual(x.toString(), y.toString());
+        assertTrue(Arrays.equals(x.toArray(), y.toArray()));
+        while (!x.isEmpty()) {
+            assertFalse(y.isEmpty());
+            mustEqual(x.remove(), y.remove());
+        }
+        assertTrue(y.isEmpty());
     }
 
     /**
      * drainTo(c) empties queue into another collection c
      */
     public void testDrainTo() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        ArrayList l = new ArrayList();
+        LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
+        ArrayList<Item> l = new ArrayList<>();
         q.drainTo(l);
-        assertEquals(q.size(), 0);
-        assertEquals(l.size(), SIZE);
+        mustEqual(0, q.size());
+        mustEqual(SIZE, l.size());
         for (int i = 0; i < SIZE; ++i)
-            assertEquals(l.get(i), new Integer(i));
+            mustEqual(l.get(i), i);
         q.add(zero);
         q.add(one);
         assertFalse(q.isEmpty());
-        assertTrue(q.contains(zero));
-        assertTrue(q.contains(one));
+        mustContain(q, zero);
+        mustContain(q, one);
         l.clear();
         q.drainTo(l);
-        assertEquals(q.size(), 0);
-        assertEquals(l.size(), 2);
+        mustEqual(0, q.size());
+        mustEqual(2, l.size());
         for (int i = 0; i < 2; ++i)
-            assertEquals(l.get(i), new Integer(i));
+            mustEqual(l.get(i), i);
     }
 
     /**
      * drainTo empties full queue, unblocking a waiting put.
      */
     public void testDrainToWithActivePut() throws InterruptedException {
-        final LinkedBlockingQueue q = populatedQueue(SIZE);
+        final LinkedBlockingQueue<Item> q = populatedQueue(SIZE);
         Thread t = new Thread(new CheckedRunnable() {
             public void realRun() throws InterruptedException {
-                q.put(new Integer(SIZE+1));
+                q.put(new Item(SIZE + 1));
             }});
 
         t.start();
-        ArrayList l = new ArrayList();
+        ArrayList<Item> l = new ArrayList<>();
         q.drainTo(l);
         assertTrue(l.size() >= SIZE);
         for (int i = 0; i < SIZE; ++i)
-            assertEquals(l.get(i), new Integer(i));
+            mustEqual(l.get(i), i);
         t.join();
         assertTrue(q.size() + l.size() >= SIZE);
     }
 
     /**
-     * drainTo(null, n) throws NPE
-     */
-    public void testDrainToNullN() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        try {
-            q.drainTo(null, 0);
-            shouldThrow();
-        } catch (NullPointerException success) {}
-    }
-
-    /**
-     * drainTo(this, n) throws IAE
-     */
-    public void testDrainToSelfN() {
-        LinkedBlockingQueue q = populatedQueue(SIZE);
-        try {
-            q.drainTo(q, 0);
-            shouldThrow();
-        } catch (IllegalArgumentException success) {}
-    }
-
-    /**
      * drainTo(c, n) empties first min(n, size) elements of queue into c
      */
     public void testDrainToN() {
-        LinkedBlockingQueue q = new LinkedBlockingQueue();
+        LinkedBlockingQueue<Item> q = new LinkedBlockingQueue<>();
         for (int i = 0; i < SIZE + 2; ++i) {
             for (int j = 0; j < SIZE; j++)
-                assertTrue(q.offer(new Integer(j)));
-            ArrayList l = new ArrayList();
+                mustOffer(q, j);
+            ArrayList<Item> l = new ArrayList<>();
             q.drainTo(l, i);
             int k = (i < SIZE) ? i : SIZE;
-            assertEquals(l.size(), k);
-            assertEquals(q.size(), SIZE-k);
+            mustEqual(k, l.size());
+            mustEqual(SIZE - k, q.size());
             for (int j = 0; j < k; ++j)
-                assertEquals(l.get(j), new Integer(j));
-            while (q.poll() != null) ;
+                mustEqual(l.get(j), j);
+            do {} while (q.poll() != null);
+        }
+    }
+
+    /**
+     * remove(null), contains(null) always return false
+     */
+    public void testNeverContainsNull() {
+        Collection<?>[] qs = {
+            new LinkedBlockingQueue<>(),
+            populatedQueue(2),
+        };
+
+        for (Collection<?> q : qs) {
+            assertFalse(q.contains(null));
+            assertFalse(q.remove(null));
         }
     }