--- jsr166/src/test/tck/LinkedTransferQueueTest.java	2009/07/31 23:02:49	1.1
+++ jsr166/src/test/tck/LinkedTransferQueueTest.java	2015/04/25 04:55:31	1.59
@@ -1,227 +1,174 @@
-
 /*
  * 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 John Vint
  */
 
-import java.io.BufferedInputStream;
-import java.io.BufferedOutputStream;
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.ObjectInputStream;
-import java.io.ObjectOutputStream;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.ConcurrentModificationException;
+import java.util.Collection;
 import java.util.Iterator;
+import java.util.List;
 import java.util.NoSuchElementException;
-import java.util.concurrent.*;
+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.LinkedTransferQueue;
+
 import junit.framework.Test;
-import junit.framework.TestSuite;
 
+@SuppressWarnings({"unchecked", "rawtypes"})
 public class LinkedTransferQueueTest extends JSR166TestCase {
 
+    public static class Generic extends BlockingQueueTest {
+        protected BlockingQueue emptyCollection() {
+            return new LinkedTransferQueue();
+        }
+    }
+
     public static void main(String[] args) {
-        junit.textui.TestRunner.run(suite());
+        main(suite(), args);
     }
 
     public static Test suite() {
-        return new TestSuite(LinkedTransferQueueTest.class);
+        return newTestSuite(LinkedTransferQueueTest.class,
+                            new Generic().testSuite());
     }
 
-    /*
-     *Constructor builds new queue with size being zero and empty being true
+    /**
+     * Constructor builds new queue with size being zero and empty
+     * being true
      */
     public void testConstructor1() {
         assertEquals(0, new LinkedTransferQueue().size());
         assertTrue(new LinkedTransferQueue().isEmpty());
     }
 
-    /*
-     * Initizialing constructor with null collection throws NPE
+    /**
+     * Initializing constructor with null collection throws
+     * NullPointerException
      */
     public void testConstructor2() {
         try {
             new LinkedTransferQueue(null);
             shouldThrow();
-        } catch (NullPointerException success) {
-        }
+        } catch (NullPointerException success) {}
     }
 
     /**
-     * Initializing from Collection of null elements throws NPE
+     * Initializing from Collection of null elements throws
+     * NullPointerException
      */
     public void testConstructor3() {
+        Collection<Integer> elements = Arrays.asList(new Integer[SIZE]);
         try {
-            Integer[] ints = new Integer[SIZE];
-            LinkedTransferQueue q = new LinkedTransferQueue(Arrays.asList(ints));
+            new LinkedTransferQueue(elements);
             shouldThrow();
-        } catch (NullPointerException success) {
-        }
+        } catch (NullPointerException success) {}
     }
-    /*
+
+    /**
      * Initializing constructor with a collection containing some null elements
-     * throws NPE
+     * throws NullPointerException
      */
-
     public void testConstructor4() {
+        Integer[] ints = new Integer[SIZE];
+        for (int i = 0; i < SIZE-1; ++i)
+            ints[i] = i;
+        Collection<Integer> elements = Arrays.asList(ints);
         try {
-            Integer[] ints = new Integer[SIZE];
-            for (int i = 0; i < SIZE - 1; ++i) {
-                ints[i] = new Integer(i);
-            }
-            LinkedTransferQueue q = new LinkedTransferQueue(Arrays.asList(ints));
+            new LinkedTransferQueue(elements);
             shouldThrow();
-        } catch (NullPointerException success) {
-        }
+        } catch (NullPointerException success) {}
     }
 
-    /*
+    /**
      * Queue contains all elements of the collection it is initialized by
      */
     public void testConstructor5() {
-        try {
-            Integer[] ints = new Integer[SIZE];
-            for (int i = 0; i < SIZE; ++i) {
-                ints[i] = new Integer(i);
-            }
-            LinkedTransferQueue q = new LinkedTransferQueue(Arrays.asList(ints));
-            for (int i = 0; i < SIZE; ++i) {
-                assertEquals(ints[i], q.poll());
-            }
-        } finally {
+        Integer[] ints = new Integer[SIZE];
+        for (int i = 0; i < SIZE; ++i) {
+            ints[i] = i;
+        }
+        List intList = Arrays.asList(ints);
+        LinkedTransferQueue q
+            = new LinkedTransferQueue(intList);
+        assertEquals(q.size(), intList.size());
+        assertEquals(q.toString(), intList.toString());
+        assertTrue(Arrays.equals(q.toArray(),
+                                     intList.toArray()));
+        assertTrue(Arrays.equals(q.toArray(new Object[0]),
+                                 intList.toArray(new Object[0])));
+        assertTrue(Arrays.equals(q.toArray(new Object[SIZE]),
+                                 intList.toArray(new Object[SIZE])));
+        for (int i = 0; i < SIZE; ++i) {
+            assertEquals(ints[i], q.poll());
         }
     }
 
     /**
-     * Remaining capacity never decrease nor increase on add or remove
+     * remainingCapacity() always returns Integer.MAX_VALUE
      */
     public void testRemainingCapacity() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
-        int remainingCapacity = q.remainingCapacity();
+        BlockingQueue q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(remainingCapacity, q.remainingCapacity());
+            assertEquals(Integer.MAX_VALUE, q.remainingCapacity());
             assertEquals(SIZE - i, q.size());
-            q.remove();
+            assertEquals(i, q.remove());
         }
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(remainingCapacity, q.remainingCapacity());
+            assertEquals(Integer.MAX_VALUE, q.remainingCapacity());
             assertEquals(i, q.size());
-            q.add(new Integer(i));
-        }
-    }
-
-    /**
-     * offer(null) throws NPE
-     */
-    public void testOfferNull() {
-        try {
-            LinkedTransferQueue q = new LinkedTransferQueue();
-            q.offer(null);
-            shouldThrow();
-        } catch (NullPointerException success) {
+            assertTrue(q.add(i));
         }
     }
 
     /**
-     * add(null) throws NPE
-     */
-    public void testAddNull() {
-        try {
-            LinkedTransferQueue q = new LinkedTransferQueue();
-            q.add(null);
-            shouldThrow();
-        } catch (NullPointerException success) {
-        }
-    }
-
-    /**
-     * addAll(null) throws NPE
-     */
-    public void testAddAll1() {
-        try {
-            LinkedTransferQueue q = new LinkedTransferQueue();
-            q.addAll(null);
-            shouldThrow();
-        } catch (NullPointerException success) {
-        }
-    }
-
-    /**
-     * addAll(this) throws IAE
+     * addAll(this) throws IllegalArgumentException
      */
     public void testAddAllSelf() {
         try {
             LinkedTransferQueue q = populatedQueue(SIZE);
             q.addAll(q);
             shouldThrow();
-        } catch (IllegalArgumentException success) {
-        }
-    }
-
-    /**
-     * addAll of a collection with null elements throws NPE
-     */
-    public void testAddAll2() {
-        try {
-            LinkedTransferQueue q = new LinkedTransferQueue();
-            Integer[] ints = new Integer[SIZE];
-            q.addAll(Arrays.asList(ints));
-            shouldThrow();
-        } catch (NullPointerException success) {
-        }
+        } catch (IllegalArgumentException success) {}
     }
 
     /**
-     * addAll of a collection with any null elements throws NPE after
-     * possibly adding some elements
+     * addAll of a collection with any null elements throws
+     * NullPointerException after possibly adding some elements
      */
     public void testAddAll3() {
         try {
             LinkedTransferQueue q = new LinkedTransferQueue();
             Integer[] ints = new Integer[SIZE];
             for (int i = 0; i < SIZE - 1; ++i) {
-                ints[i] = new Integer(i);
+                ints[i] = i;
             }
             q.addAll(Arrays.asList(ints));
             shouldThrow();
-        } catch (NullPointerException success) {
-        }
+        } catch (NullPointerException success) {}
     }
 
     /**
      * Queue contains all elements, in traversal order, of successful addAll
      */
     public void testAddAll5() {
-        try {
-            Integer[] empty = new Integer[0];
-            Integer[] ints = new Integer[SIZE];
-            for (int i = 0; i < SIZE; ++i) {
-                ints[i] = new Integer(i);
-            }
-            LinkedTransferQueue q = new LinkedTransferQueue();
-            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 {
+        Integer[] empty = new Integer[0];
+        Integer[] ints = new Integer[SIZE];
+        for (int i = 0; i < SIZE; ++i) {
+            ints[i] = i;
         }
-    }
-
-    /**
-     * put(null) throws NPE
-     */
-    public void testPutNull() {
-        try {
-            LinkedTransferQueue q = new LinkedTransferQueue();
-            q.put(null);
-            shouldThrow();
-        } catch (NullPointerException success) {
-        } catch (Exception ie) {
-            unexpectedException();
+        LinkedTransferQueue q = new LinkedTransferQueue();
+        assertFalse(q.addAll(Arrays.asList(empty)));
+        assertTrue(q.addAll(Arrays.asList(ints)));
+        for (int i = 0; i < SIZE; ++i) {
+            assertEquals(ints[i], q.poll());
         }
     }
 
@@ -229,305 +176,256 @@ public class LinkedTransferQueueTest ext
      * all elements successfully put are contained
      */
     public void testPut() {
-        try {
-            LinkedTransferQueue q = new LinkedTransferQueue();
-            for (int i = 0; i < SIZE; ++i) {
-                Integer I = new Integer(i);
-                q.put(I);
-                assertTrue(q.contains(I));
-            }
-        } catch (Exception ie) {
-            unexpectedException();
+        LinkedTransferQueue<Integer> q = new LinkedTransferQueue<Integer>();
+        for (int i = 0; i < SIZE; ++i) {
+            assertEquals(i, q.size());
+            q.put(i);
+            assertTrue(q.contains(i));
         }
     }
 
     /**
      * take retrieves elements in FIFO order
      */
-    public void testTake() {
-        try {
-            LinkedTransferQueue q = populatedQueue(SIZE);
-            for (int i = 0; i < SIZE; ++i) {
-                assertEquals(i, ((Integer) q.take()).intValue());
-            }
-        } catch (InterruptedException e) {
-            unexpectedException();
+    public void testTake() throws InterruptedException {
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
+        for (int i = 0; i < SIZE; ++i) {
+            assertEquals(i, (int) q.take());
         }
     }
 
     /**
-     * take blocks interruptibly when empty
+     * take removes existing elements until empty, then blocks interruptibly
      */
-    public void testTakeFromEmpty() {
-        final LinkedTransferQueue q = new LinkedTransferQueue();
-        Thread t = new Thread(new Runnable() {
+    public void testBlockingTake() throws InterruptedException {
+        final BlockingQueue 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());
+                }
 
-            public void run() {
+                Thread.currentThread().interrupt();
                 try {
                     q.take();
-                    threadShouldThrow();
-                } catch (InterruptedException success) {
-                }
-            }
-        });
-        try {
-            t.start();
-            Thread.sleep(SHORT_DELAY_MS);
-            t.interrupt();
-            t.join();
-        } catch (Exception e) {
-            unexpectedException();
-        }
-    }
-    /*
-     * Take removes existing elements until empty, then blocks interruptibly
-     */
-
-    public void testBlockingTake() {
-        Thread t = new Thread(new Runnable() {
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
 
-            public void run() {
+                pleaseInterrupt.countDown();
                 try {
-                    LinkedTransferQueue 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();
-        }
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
+            }});
+
+        await(pleaseInterrupt);
+        assertThreadStaysAlive(t);
+        t.interrupt();
+        awaitTermination(t);
     }
 
     /**
      * poll succeeds unless empty
      */
-    public void testPoll() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
+    public void testPoll() throws InterruptedException {
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, ((Integer) q.poll()).intValue());
+            assertEquals(i, (int) q.poll());
         }
         assertNull(q.poll());
+        checkEmpty(q);
     }
 
     /**
-     * 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() {
-        try {
-            LinkedTransferQueue 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 void testTimedPoll0() throws InterruptedException {
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
+        for (int i = 0; i < SIZE; ++i) {
+            assertEquals(i, (int) q.poll(0, MILLISECONDS));
         }
+        assertNull(q.poll(0, MILLISECONDS));
+        checkEmpty(q);
     }
 
     /**
-     * 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() {
-        try {
-            LinkedTransferQueue 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 void testTimedPoll() throws InterruptedException {
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
+        for (int i = 0; i < SIZE; ++i) {
+            long startTime = System.nanoTime();
+            assertEquals(i, (int) 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);
     }
 
     /**
      * Interrupted timed poll throws InterruptedException instead of
      * returning timeout status
      */
-    public void testInterruptedTimedPoll() {
-        Thread t = new Thread(new Runnable() {
-
-            public void run() {
+    public void testInterruptedTimedPoll() throws InterruptedException {
+        final BlockingQueue<Integer> q = populatedQueue(SIZE);
+        final CountDownLatch aboutToWait = new CountDownLatch(1);
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                for (int i = 0; i < SIZE; ++i) {
+                    long t0 = System.nanoTime();
+                    assertEquals(i, (int) q.poll(LONG_DELAY_MS, MILLISECONDS));
+                    assertTrue(millisElapsedSince(t0) < SMALL_DELAY_MS);
+                }
+                long t0 = System.nanoTime();
+                aboutToWait.countDown();
                 try {
-                    LinkedTransferQueue 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));
+                    q.poll(MEDIUM_DELAY_MS, MILLISECONDS);
+                    shouldThrow();
                 } catch (InterruptedException success) {
+                    assertTrue(millisElapsedSince(t0) < MEDIUM_DELAY_MS);
                 }
-            }
-        });
-        t.start();
-        try {
-            Thread.sleep(SHORT_DELAY_MS);
-            t.interrupt();
-            t.join();
-        } catch (InterruptedException ie) {
-            unexpectedException();
-        }
+            }});
+
+        aboutToWait.await();
+        waitForThreadToEnterWaitState(t, SMALL_DELAY_MS);
+        t.interrupt();
+        awaitTermination(t, MEDIUM_DELAY_MS);
+        checkEmpty(q);
     }
 
     /**
-     *  timed poll before a delayed offer fails; after offer succeeds;
-     *  on interruption throws
-     */
-    public void testTimedPollWithOffer() {
-        final LinkedTransferQueue q = new LinkedTransferQueue();
-        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) {
+     * timed poll after thread interrupted throws InterruptedException
+     * instead of returning timeout status
+     */
+    public void testTimedPollAfterInterrupt() throws InterruptedException {
+        final BlockingQueue<Integer> q = populatedQueue(SIZE);
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                Thread.currentThread().interrupt();
+                for (int i = 0; i < SIZE; ++i) {
+                    long t0 = System.nanoTime();
+                    assertEquals(i, (int) q.poll(LONG_DELAY_MS, MILLISECONDS));
+                    assertTrue(millisElapsedSince(t0) < SMALL_DELAY_MS);
                 }
-            }
-        });
-        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();
-        }
+                try {
+                    q.poll(MEDIUM_DELAY_MS, MILLISECONDS);
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+            }});
+
+        awaitTermination(t, MEDIUM_DELAY_MS);
+        checkEmpty(q);
     }
 
     /**
      * peek returns next element, or null if empty
      */
-    public void testPeek() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
+    public void testPeek() throws InterruptedException {
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, ((Integer) q.peek()).intValue());
-            q.poll();
+            assertEquals(i, (int) q.peek());
+            assertEquals(i, (int) q.poll());
             assertTrue(q.peek() == null ||
-                    i != ((Integer) q.peek()).intValue());
+                       i != (int) q.peek());
         }
         assertNull(q.peek());
+        checkEmpty(q);
     }
 
     /**
-     * element returns next element, or throws NSEE if empty
+     * element returns next element, or throws NoSuchElementException if empty
      */
-    public void testElement() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
+    public void testElement() throws InterruptedException {
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, ((Integer) q.element()).intValue());
-            q.poll();
+            assertEquals(i, (int) q.element());
+            assertEquals(i, (int) q.poll());
         }
         try {
             q.element();
             shouldThrow();
-        } catch (NoSuchElementException success) {
-        }
+        } catch (NoSuchElementException success) {}
+        checkEmpty(q);
     }
 
     /**
-     * remove removes next element, or throws NSEE if empty
+     * remove removes next element, or throws NoSuchElementException if empty
      */
-    public void testRemove() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
+    public void testRemove() throws InterruptedException {
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(i, ((Integer) q.remove()).intValue());
+            assertEquals(i, (int) q.remove());
         }
         try {
             q.remove();
             shouldThrow();
-        } catch (NoSuchElementException success) {
-        }
-    }
-
-    /**
-     * remove(x) removes x and returns true if present
-     */
-    public void testRemoveElement() {
-        LinkedTransferQueue 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());
+        } catch (NoSuchElementException success) {}
+        checkEmpty(q);
     }
 
     /**
      * An add following remove(x) succeeds
      */
-    public void testRemoveElementAndAdd() {
-        try {
-            LinkedTransferQueue q = new LinkedTransferQueue();
-            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);
-        } catch (Exception e) {
-            unexpectedException();
-        }
+    public void testRemoveElementAndAdd() throws InterruptedException {
+        LinkedTransferQueue q = new LinkedTransferQueue();
+        assertTrue(q.add(one));
+        assertTrue(q.add(two));
+        assertTrue(q.remove(one));
+        assertTrue(q.remove(two));
+        assertTrue(q.add(three));
+        assertSame(q.take(), three);
     }
 
     /**
      * contains(x) reports true when elements added but not yet removed
      */
     public void testContains() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
         for (int i = 0; i < SIZE; ++i) {
-            assertTrue(q.contains(new Integer(i)));
-            q.poll();
-            assertFalse(q.contains(new Integer(i)));
+            assertTrue(q.contains(i));
+            assertEquals(i, (int) q.poll());
+            assertFalse(q.contains(i));
         }
     }
 
     /**
      * clear removes all elements
      */
-    public void testClear() {
+    public void testClear() throws InterruptedException {
         LinkedTransferQueue q = populatedQueue(SIZE);
-        int remainingCapacity = q.remainingCapacity();
         q.clear();
-        assertTrue(q.isEmpty());
-        assertEquals(0, q.size());
-        assertEquals(remainingCapacity, q.remainingCapacity());
+        checkEmpty(q);
+        assertEquals(Integer.MAX_VALUE, q.remainingCapacity());
         q.add(one);
         assertFalse(q.isEmpty());
+        assertEquals(1, q.size());
         assertTrue(q.contains(one));
         q.clear();
-        assertTrue(q.isEmpty());
+        checkEmpty(q);
     }
 
     /**
      * containsAll(c) is true when c contains a subset of elements
      */
     public void testContainsAll() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
-        LinkedTransferQueue p = new LinkedTransferQueue();
+        LinkedTransferQueue<Integer> q = populatedQueue(SIZE);
+        LinkedTransferQueue<Integer> p = new LinkedTransferQueue<Integer>();
         for (int i = 0; i < SIZE; ++i) {
             assertTrue(q.containsAll(p));
             assertFalse(p.containsAll(q));
-            p.add(new Integer(i));
+            p.add(i);
         }
         assertTrue(p.containsAll(q));
     }
 
     /**
-     * retainAll(c) retains only those elements of c and reports true if changed
+     * retainAll(c) retains only those elements of c and reports true
+     * if changed
      */
     public void testRetainAll() {
         LinkedTransferQueue q = populatedQueue(SIZE);
@@ -546,7 +444,8 @@ public class LinkedTransferQueueTest ext
     }
 
     /**
-     * removeAll(c) removes only those elements of c and reports true if changed
+     * removeAll(c) removes only those elements of c and reports true
+     * if changed
      */
     public void testRemoveAll() {
         for (int i = 1; i < SIZE; ++i) {
@@ -555,84 +454,74 @@ public class LinkedTransferQueueTest ext
             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));
+                assertFalse(q.contains(p.remove()));
             }
         }
     }
 
     /**
-     * toArray contains all elements
+     * toArray() contains all elements in FIFO order
      */
     public void testToArray() {
         LinkedTransferQueue 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();
+        for (int i = 0; i < o.length; i++) {
+            assertSame(o[i], q.poll());
         }
     }
 
     /**
-     * toArray(a) contains all elements
+     * toArray(a) contains all elements in FIFO order
      */
     public void testToArray2() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
+        LinkedTransferQueue<Integer> 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();
-        }
-    }
-
-    /**
-     * toArray(null) throws NPE
-     */
-    public void testToArray_BadArg() {
-        try {
-            LinkedTransferQueue q = populatedQueue(SIZE);
-            Object o[] = q.toArray(null);
-            shouldThrow();
-        } catch (NullPointerException success) {
+        Integer[] array = q.toArray(ints);
+        assertSame(ints, array);
+        for (int i = 0; i < ints.length; i++) {
+            assertSame(ints[i], q.poll());
         }
     }
 
     /**
-     * toArray with incompatible array type throws CCE
+     * toArray(incompatible array type) throws ArrayStoreException
      */
     public void testToArray1_BadArg() {
+        LinkedTransferQueue q = populatedQueue(SIZE);
         try {
-            LinkedTransferQueue q = populatedQueue(SIZE);
-            Object o[] = q.toArray(new String[10]);
+            q.toArray(new String[10]);
             shouldThrow();
-        } catch (ArrayStoreException success) {
-        }
+        } catch (ArrayStoreException success) {}
     }
 
     /**
      * iterator iterates through all elements
      */
-    public void testIterator() {
+    public void testIterator() throws InterruptedException {
         LinkedTransferQueue q = populatedQueue(SIZE);
         Iterator it = q.iterator();
-        try {
-            while (it.hasNext()) {
-                assertEquals(it.next(), q.take());
-            }
-        } catch (InterruptedException e) {
-            unexpectedException();
-        }
+        int i;
+        for (i = 0; it.hasNext(); i++)
+            assertTrue(q.contains(it.next()));
+        assertEquals(i, SIZE);
+        assertIteratorExhausted(it);
+
+        it = q.iterator();
+        for (i = 0; it.hasNext(); i++)
+            assertEquals(it.next(), q.take());
+        assertEquals(i, SIZE);
+        assertIteratorExhausted(it);
+    }
+
+    /**
+     * iterator of empty collection has no elements
+     */
+    public void testEmptyIterator() {
+        assertIteratorExhausted(new LinkedTransferQueue().iterator());
     }
 
     /**
-     * iterator.remove removes current element
+     * iterator.remove() removes current element
      */
     public void testIteratorRemove() {
         final LinkedTransferQueue q = new LinkedTransferQueue();
@@ -645,8 +534,8 @@ public class LinkedTransferQueueTest ext
         it.remove();
 
         it = q.iterator();
-        assertEquals(it.next(), one);
-        assertEquals(it.next(), three);
+        assertSame(it.next(), one);
+        assertSame(it.next(), three);
         assertFalse(it.hasNext());
     }
 
@@ -654,16 +543,16 @@ public class LinkedTransferQueueTest ext
      * iterator ordering is FIFO
      */
     public void testIteratorOrdering() {
-        final LinkedTransferQueue q = new LinkedTransferQueue();
-        int remainingCapacity = q.remainingCapacity();
+        final LinkedTransferQueue<Integer> q
+            = new LinkedTransferQueue<Integer>();
+        assertEquals(Integer.MAX_VALUE, q.remainingCapacity());
         q.add(one);
         q.add(two);
         q.add(three);
-        assertEquals(remainingCapacity, q.remainingCapacity());
+        assertEquals(Integer.MAX_VALUE, q.remainingCapacity());
         int k = 0;
-        for (Iterator it = q.iterator(); it.hasNext();) {
-            int i = ((Integer) (it.next())).intValue();
-            assertEquals(++k, i);
+        for (Integer n : q) {
+            assertEquals(++k, (int) n);
         }
         assertEquals(3, k);
     }
@@ -676,13 +565,9 @@ public class LinkedTransferQueueTest ext
         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();
+        for (Iterator it = q.iterator(); it.hasNext();) {
+            q.remove();
+            it.next();
         }
         assertEquals(0, q.size());
     }
@@ -694,7 +579,7 @@ public class LinkedTransferQueueTest ext
         LinkedTransferQueue 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)));
         }
     }
 
@@ -703,65 +588,46 @@ public class LinkedTransferQueueTest ext
      */
     public void testOfferInExecutor() {
         final LinkedTransferQueue q = new LinkedTransferQueue();
-        q.add(one);
-        q.add(two);
+        final CheckedBarrier threadsStarted = new CheckedBarrier(2);
         ExecutorService executor = Executors.newFixedThreadPool(2);
-        executor.execute(new Runnable() {
 
-            public void run() {
-                try {
-                    threadAssertTrue(q.offer(three, MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS));
-                } catch (Exception e) {
-                    threadUnexpectedException();
-                }
-            }
-        });
-
-        executor.execute(new Runnable() {
-
-            public void run() {
-                try {
-                    Thread.sleep(SMALL_DELAY_MS);
-                    threadAssertEquals(one, q.take());
-                } catch (InterruptedException e) {
-                    threadUnexpectedException();
-                }
-            }
-        });
+        executor.execute(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                threadsStarted.await();
+                assertTrue(q.offer(one, LONG_DELAY_MS, MILLISECONDS));
+            }});
+
+        executor.execute(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                threadsStarted.await();
+                assertSame(one, q.take());
+                checkEmpty(q);
+            }});
 
         joinPool(executor);
     }
 
     /**
-     * poll retrieves elements across Executor threads
+     * timed poll retrieves elements across Executor threads
      */
     public void testPollInExecutor() {
         final LinkedTransferQueue q = new LinkedTransferQueue();
+        final CheckedBarrier threadsStarted = new CheckedBarrier(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();
-                }
-            }
-        });
+        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);
+            }});
 
         joinPool(executor);
     }
@@ -769,50 +635,19 @@ public class LinkedTransferQueueTest ext
     /**
      * A deserialized serialized queue has same elements in same order
      */
-    public void testSerialization() {
-        LinkedTransferQueue 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));
-            LinkedTransferQueue r = (LinkedTransferQueue) in.readObject();
-
-            assertEquals(q.size(), r.size());
-            while (!q.isEmpty()) {
-                assertEquals(q.remove(), r.remove());
-            }
-        } catch (Exception e) {
-            unexpectedException();
-        }
-    }
-
-    /**
-     * drainTo(null) throws NPE
-     */
-    public void testDrainToNull() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
-        try {
-            q.drainTo(null);
-            shouldThrow();
-        } catch (NullPointerException success) {
-        }
-    }
-
-    /**
-     * drainTo(this) throws IAE
-     */
-    public void testDrainToSelf() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
-        try {
-            q.drainTo(q);
-            shouldThrow();
-        } catch (IllegalArgumentException success) {
+    public void testSerialization() throws Exception {
+        Queue x = populatedQueue(SIZE);
+        Queue y = serialClone(x);
+
+        assertNotSame(y, x);
+        assertEquals(x.size(), y.size());
+        assertEquals(x.toString(), y.toString());
+        assertTrue(Arrays.equals(x.toArray(), y.toArray()));
+        while (!x.isEmpty()) {
+            assertFalse(y.isEmpty());
+            assertEquals(x.remove(), y.remove());
         }
+        assertTrue(y.isEmpty());
     }
 
     /**
@@ -822,10 +657,10 @@ public class LinkedTransferQueueTest ext
         LinkedTransferQueue q = populatedQueue(SIZE);
         ArrayList l = new ArrayList();
         q.drainTo(l);
-        assertEquals(q.size(), 0);
-        assertEquals(l.size(), SIZE);
+        assertEquals(0, q.size());
+        assertEquals(SIZE, l.size());
         for (int i = 0; i < SIZE; ++i) {
-            assertEquals(l.get(i), new Integer(i));
+            assertEquals(i, l.get(i));
         }
         q.add(zero);
         q.add(one);
@@ -834,414 +669,376 @@ public class LinkedTransferQueueTest ext
         assertTrue(q.contains(one));
         l.clear();
         q.drainTo(l);
-        assertEquals(q.size(), 0);
-        assertEquals(l.size(), 2);
+        assertEquals(0, q.size());
+        assertEquals(2, l.size());
         for (int i = 0; i < 2; ++i) {
-            assertEquals(l.get(i), new Integer(i));
+            assertEquals(i, l.get(i));
         }
     }
 
     /**
-     * drainTo empties full queue, unblocking a waiting put.
+     * drainTo(c) empties full queue, unblocking a waiting put.
      */
-    public void testDrainToWithActivePut() {
+    public void testDrainToWithActivePut() throws InterruptedException {
         final LinkedTransferQueue q = populatedQueue(SIZE);
-        Thread t = new Thread(new Runnable() {
-
-            public void run() {
-                try {
-                    q.put(new Integer(SIZE + 1));
-                } catch (Exception 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();
-        }
-    }
-
-    /**
-     * drainTo(null, n) throws NPE
-     */
-    public void testDrainToNullN() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
-        try {
-            q.drainTo(null, 0);
-            shouldThrow();
-        } catch (NullPointerException success) {
-        }
-    }
-
-    /**
-     * drainTo(this, n) throws IAE
-     */
-    public void testDrainToSelfN() {
-        LinkedTransferQueue q = populatedQueue(SIZE);
-        try {
-            q.drainTo(q, 0);
-            shouldThrow();
-        } catch (IllegalArgumentException success) {
-        }
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() {
+                q.put(SIZE + 1);
+            }});
+        ArrayList l = new ArrayList();
+        q.drainTo(l);
+        assertTrue(l.size() >= SIZE);
+        for (int i = 0; i < SIZE; ++i)
+            assertEquals(i, l.get(i));
+        awaitTermination(t, MEDIUM_DELAY_MS);
+        assertTrue(q.size() + l.size() >= SIZE);
     }
 
     /**
-     * drainTo(c, n) empties first max {n, size} elements of queue into c
+     * drainTo(c, n) empties first min(n, size) elements of queue into c
      */
     public void testDrainToN() {
         LinkedTransferQueue q = new LinkedTransferQueue();
         for (int i = 0; i < SIZE + 2; ++i) {
             for (int j = 0; j < SIZE; j++) {
-                assertTrue(q.offer(new Integer(j)));
+                assertTrue(q.offer(j));
             }
             ArrayList l = new ArrayList();
             q.drainTo(l, i);
             int k = (i < SIZE) ? i : SIZE;
-            assertEquals(l.size(), k);
-            assertEquals(q.size(), SIZE - k);
-            for (int j = 0; j < k; ++j) {
-                assertEquals(l.get(j), new Integer(j));
-            }
-            while (q.poll() != null);
+            assertEquals(k, l.size());
+            assertEquals(SIZE - k, q.size());
+            for (int j = 0; j < k; ++j)
+                assertEquals(j, l.get(j));
+            do {} while (q.poll() != null);
         }
     }
 
-    /*
-     * poll and take should decrement the waiting consumer count
+    /**
+     * timed poll() or take() increments the waiting consumer count;
+     * offer(e) decrements the waiting consumer count
      */
-    public void testWaitingConsumer() {
-        try {
-            final LinkedTransferQueue q = new LinkedTransferQueue();
-            final ConsumerObserver waiting = new ConsumerObserver();
-            new Thread(new Runnable() {
+    public void testWaitingConsumer() throws InterruptedException {
+        final LinkedTransferQueue q = new LinkedTransferQueue();
+        assertEquals(0, q.getWaitingConsumerCount());
+        assertFalse(q.hasWaitingConsumer());
+        final CountDownLatch threadStarted = new CountDownLatch(1);
 
-                public void run() {
-                    try {
-                        threadAssertTrue(q.hasWaitingConsumer());
-                        waiting.setWaitingConsumer(q.getWaitingConsumerCount());
-                        threadAssertTrue(q.offer(new Object()));
-                    } catch (Exception ex) {
-                        threadUnexpectedException();
-                    }
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                threadStarted.countDown();
+                assertSame(one, q.poll(LONG_DELAY_MS, MILLISECONDS));
+                assertEquals(0, q.getWaitingConsumerCount());
+                assertFalse(q.hasWaitingConsumer());
+            }});
 
-                }
-            }).start();
-            assertTrue(q.poll(LONG_DELAY_MS, TimeUnit.MILLISECONDS) != null);
-            assertTrue(q.getWaitingConsumerCount() < waiting.getWaitingConsumers());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+        threadStarted.await();
+        waitForThreadToEnterWaitState(t, SMALL_DELAY_MS);
+        assertEquals(1, q.getWaitingConsumerCount());
+        assertTrue(q.hasWaitingConsumer());
+
+        assertTrue(q.offer(one));
+        assertEquals(0, q.getWaitingConsumerCount());
+        assertFalse(q.hasWaitingConsumer());
+
+        awaitTermination(t, MEDIUM_DELAY_MS);
     }
-    /*
-     * Inserts null into transfer throws NPE
-     */
 
-    public void testTransfer1() {
+    /**
+     * transfer(null) throws NullPointerException
+     */
+    public void testTransfer1() throws InterruptedException {
         try {
             LinkedTransferQueue q = new LinkedTransferQueue();
             q.transfer(null);
             shouldThrow();
-        } catch (NullPointerException ex) {
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+        } catch (NullPointerException success) {}
     }
 
-    /*
-     * transfer attempts to insert into the queue then wait until that 
-     * object is removed via take or poll. 
+    /**
+     * transfer waits until a poll occurs. The transfered element
+     * is returned by this associated poll.
      */
-    public void testTransfer2() {
-        final LinkedTransferQueue<Integer> q = new LinkedTransferQueue<Integer>();
-        new Thread(new Runnable() {
+    public void testTransfer2() throws InterruptedException {
+        final LinkedTransferQueue<Integer> q
+            = new LinkedTransferQueue<Integer>();
+        final CountDownLatch threadStarted = new CountDownLatch(1);
 
-            public void run() {
-                try {
-                    q.transfer(new Integer(SIZE));
-                    threadAssertTrue(q.isEmpty());
-                } catch (Exception ex) {
-                    threadUnexpectedException();
-                }
-            }
-        }).start();
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                threadStarted.countDown();
+                q.transfer(five);
+                checkEmpty(q);
+            }});
 
-        try {
-            Thread.sleep(SHORT_DELAY_MS);
-            assertEquals(1, q.size());
-            q.poll();
-            assertTrue(q.isEmpty());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
-    }
-    /*
-     * transfer will attempt to transfer in fifo order and continue waiting if 
-     * the element being transfered is not polled or taken 
-     */
-
-    public void testTransfer3() {
-        final LinkedTransferQueue<Integer> q = new LinkedTransferQueue<Integer>();
-        new Thread(new Runnable() {
-                public void run() {
-                    try {
-                        Integer i;
-                        q.transfer((i = new Integer(SIZE + 1)));
-                        threadAssertTrue(!q.contains(i));
-                        threadAssertEquals(1, q.size());
-                    } catch (Exception ex) {
-                        threadUnexpectedException();
-                    }
-                }
-            }).start();
-        Thread interruptedThread = 
-            new Thread(new Runnable() {
-                    public void run() {
-                        try {
-                            q.transfer(new Integer(SIZE));
-                            threadShouldThrow();
-                        } catch (InterruptedException ex) {
-                        }
-                    }
-                });
-        interruptedThread.start();
-        try {
-            Thread.sleep(LONG_DELAY_MS);
-            assertEquals(2, q.size());
-            q.poll();
-            Thread.sleep(LONG_DELAY_MS);
-            interruptedThread.interrupt();
-            assertEquals(1, q.size());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+        threadStarted.await();
+        waitForThreadToEnterWaitState(t, SMALL_DELAY_MS);
+        assertEquals(1, q.size());
+        assertSame(five, q.poll());
+        checkEmpty(q);
+        awaitTermination(t, MEDIUM_DELAY_MS);
+    }
+
+    /**
+     * transfer waits until a poll occurs, and then transfers in fifo order
+     */
+    public void testTransfer3() throws InterruptedException {
+        final LinkedTransferQueue<Integer> q
+            = new LinkedTransferQueue<Integer>();
+
+        Thread first = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                q.transfer(four);
+                assertTrue(!q.contains(four));
+                assertEquals(1, q.size());
+            }});
+
+        Thread interruptedThread = newStartedThread(
+            new CheckedInterruptedRunnable() {
+                public void realRun() throws InterruptedException {
+                    while (q.isEmpty())
+                        Thread.yield();
+                    q.transfer(five);
+                }});
+
+        while (q.size() < 2)
+            Thread.yield();
+        assertEquals(2, q.size());
+        assertSame(four, q.poll());
+        first.join();
+        assertEquals(1, q.size());
+        interruptedThread.interrupt();
+        interruptedThread.join();
+        checkEmpty(q);
     }
 
     /**
-     * transfer will wait as long as a poll or take occurs if one does occur
-     * the waiting is finished and the thread that tries to poll/take 
-     * wins in retrieving the element
+     * transfer waits until a poll occurs, at which point the polling
+     * thread returns the element
      */
-    public void testTransfer4() {
+    public void testTransfer4() throws InterruptedException {
         final LinkedTransferQueue q = new LinkedTransferQueue();
-        new Thread(new Runnable() {
 
-            public void run() {
-                try {
-                    q.transfer(new Integer(four));
-                    threadAssertFalse(q.contains(new Integer(four)));
-                    threadAssertEquals(new Integer(three), q.poll());
-                } catch (Exception ex) {
-                    threadUnexpectedException();
-                }
-            }
-        }).start();
-        try {
-            Thread.sleep(MEDIUM_DELAY_MS);
-            assertTrue(q.offer(three));
-            assertEquals(new Integer(four), q.poll());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                q.transfer(four);
+                assertFalse(q.contains(four));
+                assertSame(three, q.poll());
+            }});
+
+        while (q.isEmpty())
+            Thread.yield();
+        assertFalse(q.isEmpty());
+        assertEquals(1, q.size());
+        assertTrue(q.offer(three));
+        assertSame(four, q.poll());
+        awaitTermination(t, MEDIUM_DELAY_MS);
     }
-    /*
-     * Insert null into trTransfer throws NPE
+
+    /**
+     * transfer waits until a take occurs. The transfered element
+     * is returned by this associated take.
      */
+    public void testTransfer5() throws InterruptedException {
+        final LinkedTransferQueue<Integer> q
+            = new LinkedTransferQueue<Integer>();
 
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                q.transfer(four);
+                checkEmpty(q);
+            }});
+
+        while (q.isEmpty())
+            Thread.yield();
+        assertFalse(q.isEmpty());
+        assertEquals(1, q.size());
+        assertSame(four, q.take());
+        checkEmpty(q);
+        awaitTermination(t, MEDIUM_DELAY_MS);
+    }
+
+    /**
+     * tryTransfer(null) throws NullPointerException
+     */
     public void testTryTransfer1() {
         try {
             final LinkedTransferQueue q = new LinkedTransferQueue();
             q.tryTransfer(null);
-            this.shouldThrow();
-        } catch (NullPointerException ex) {
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+            shouldThrow();
+        } catch (NullPointerException success) {}
     }
-    /*
-     * tryTransfer returns false and does not enqueue if there are no consumers
-     * waiting to poll or take.
-     */
 
-    public void testTryTransfer2() {
-        try {
-            final LinkedTransferQueue q = new LinkedTransferQueue();
-            assertFalse(q.tryTransfer(new Object()));
-            assertEquals(0, q.size());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+    /**
+     * tryTransfer returns false and does not enqueue if there are no
+     * consumers waiting to poll or take.
+     */
+    public void testTryTransfer2() throws InterruptedException {
+        final LinkedTransferQueue q = new LinkedTransferQueue();
+        assertFalse(q.tryTransfer(new Object()));
+        assertFalse(q.hasWaitingConsumer());
+        checkEmpty(q);
     }
-    /*
-     * if there is a consumer waiting poll or take tryTransfer returns
-     * true while enqueueing object
+
+    /**
+     * If there is a consumer waiting in timed poll, tryTransfer
+     * returns true while successfully transfering object.
      */
+    public void testTryTransfer3() throws InterruptedException {
+        final Object hotPotato = new Object();
+        final LinkedTransferQueue q = new LinkedTransferQueue();
 
-    public void testTryTransfer3() {
-        try {
-            final LinkedTransferQueue q = new LinkedTransferQueue();
-            new Thread(new Runnable() {
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() {
+                while (! q.hasWaitingConsumer())
+                    Thread.yield();
+                assertTrue(q.hasWaitingConsumer());
+                checkEmpty(q);
+                assertTrue(q.tryTransfer(hotPotato));
+            }});
+
+        assertSame(hotPotato, q.poll(MEDIUM_DELAY_MS, MILLISECONDS));
+        checkEmpty(q);
+        awaitTermination(t, MEDIUM_DELAY_MS);
+    }
 
-                public void run() {
-                    try {
-                        threadAssertTrue(q.hasWaitingConsumer());
-                        threadAssertTrue(q.tryTransfer(new Object()));
-                    } catch (Exception ex) {
-                        threadUnexpectedException();
-                    }
+    /**
+     * If there is a consumer waiting in take, tryTransfer returns
+     * true while successfully transfering object.
+     */
+    public void testTryTransfer4() throws InterruptedException {
+        final Object hotPotato = new Object();
+        final LinkedTransferQueue q = new LinkedTransferQueue();
 
-                }
-            }).start();
-            assertTrue(q.poll(LONG_DELAY_MS, TimeUnit.MILLISECONDS) != null);
-            assertTrue(q.isEmpty());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() {
+                while (! q.hasWaitingConsumer())
+                    Thread.yield();
+                assertTrue(q.hasWaitingConsumer());
+                checkEmpty(q);
+                assertTrue(q.tryTransfer(hotPotato));
+            }});
+
+        assertSame(q.take(), hotPotato);
+        checkEmpty(q);
+        awaitTermination(t, MEDIUM_DELAY_MS);
     }
 
-    /*
-     * tryTransfer waits the amount given if interrupted, show an
-     * interrupted exception
+    /**
+     * tryTransfer blocks interruptibly if no takers
      */
-    public void testTryTransfer4() {
+    public void testTryTransfer5() throws InterruptedException {
         final LinkedTransferQueue q = new LinkedTransferQueue();
-        Thread toInterrupt = new Thread(new Runnable() {
+        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
+        assertTrue(q.isEmpty());
 
-            public void run() {
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                Thread.currentThread().interrupt();
                 try {
-                    q.tryTransfer(new Object(), LONG_DELAY_MS, TimeUnit.MILLISECONDS);
-                    threadShouldThrow();
-                } catch (InterruptedException ex) {
-                }
-            }
-        });
-        try {
-            toInterrupt.start();
-            Thread.sleep(SMALL_DELAY_MS);
-            toInterrupt.interrupt();
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+                    q.tryTransfer(new Object(), LONG_DELAY_MS, MILLISECONDS);
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
+
+                pleaseInterrupt.countDown();
+                try {
+                    q.tryTransfer(new Object(), LONG_DELAY_MS, MILLISECONDS);
+                    shouldThrow();
+                } catch (InterruptedException success) {}
+                assertFalse(Thread.interrupted());
+            }});
+
+        await(pleaseInterrupt);
+        assertThreadStaysAlive(t);
+        t.interrupt();
+        awaitTermination(t);
+        checkEmpty(q);
     }
 
-    /*
-     * tryTransfer gives up after the timeout and return false
+    /**
+     * tryTransfer gives up after the timeout and returns false
      */
-    public void testTryTransfer5() {
+    public void testTryTransfer6() throws InterruptedException {
         final LinkedTransferQueue q = new LinkedTransferQueue();
-        try {
-            new Thread(new Runnable() {
 
-                public void run() {
-                    try {
-                        threadAssertFalse(q.tryTransfer(new Object(), SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
-                    } catch (InterruptedException ex) {
-                        threadUnexpectedException();
-                    }
-                }
-            }).start();
-            Thread.sleep(LONG_DELAY_MS);
-            assertTrue(q.isEmpty());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                long t0 = System.nanoTime();
+                assertFalse(q.tryTransfer(new Object(),
+                                          timeoutMillis(), MILLISECONDS));
+                assertTrue(millisElapsedSince(t0) >= timeoutMillis());
+                checkEmpty(q);
+            }});
+
+        awaitTermination(t);
+        checkEmpty(q);
     }
 
-    /*
+    /**
      * tryTransfer waits for any elements previously in to be removed
      * before transfering to a poll or take
      */
-    public void testTryTransfer6() {
+    public void testTryTransfer7() throws InterruptedException {
         final LinkedTransferQueue q = new LinkedTransferQueue();
-        q.offer(new Integer(four));
-        new Thread(new Runnable() {
+        assertTrue(q.offer(four));
 
-            public void run() {
-                try {
-                    threadAssertTrue(q.tryTransfer(new Integer(five), LONG_DELAY_MS, TimeUnit.MILLISECONDS));
-                    threadAssertTrue(q.isEmpty());
-                } catch (InterruptedException ex) {
-                    threadUnexpectedException();
-                }
-            }
-        }).start();
-        try {
-            Thread.sleep(SHORT_DELAY_MS);
-            assertEquals(2, q.size());
-            assertEquals(new Integer(four), q.poll());
-            assertEquals(new Integer(five), q.poll());
-            assertTrue(q.isEmpty());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+        Thread t = newStartedThread(new CheckedRunnable() {
+            public void realRun() throws InterruptedException {
+                assertTrue(q.tryTransfer(five, MEDIUM_DELAY_MS, MILLISECONDS));
+                checkEmpty(q);
+            }});
+
+        while (q.size() != 2)
+            Thread.yield();
+        assertEquals(2, q.size());
+        assertSame(four, q.poll());
+        assertSame(five, q.poll());
+        checkEmpty(q);
+        awaitTermination(t, MEDIUM_DELAY_MS);
     }
 
-    /*
-     * tryTransfer attempts to enqueue into the q and fails returning false not 
-     * enqueueing and the successing poll is null
+    /**
+     * tryTransfer attempts to enqueue into the queue and fails
+     * returning false not enqueueing and the successive poll is null
      */
-    public void testTryTransfer7() {
+    public void testTryTransfer8() throws InterruptedException {
         final LinkedTransferQueue q = new LinkedTransferQueue();
-        q.offer(new Integer(four));
-        new Thread(new Runnable() {
-
-            public void run() {
-                try {
-                    threadAssertFalse(q.tryTransfer(new Integer(five), SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
-                    threadAssertTrue(q.isEmpty());
-                } catch (InterruptedException ex) {
-                    threadUnexpectedException();
-                }
-            }
-        }).start();
-        try {
-            assertEquals(1, q.size());
-            assertEquals(new Integer(four), q.poll());
-            Thread.sleep(MEDIUM_DELAY_MS);
-            assertNull(q.poll());
-        } catch (Exception ex) {
-            this.unexpectedException();
-        }
+        assertTrue(q.offer(four));
+        assertEquals(1, q.size());
+        long t0 = System.nanoTime();
+        assertFalse(q.tryTransfer(five, timeoutMillis(), MILLISECONDS));
+        assertTrue(millisElapsedSince(t0) >= timeoutMillis());
+        assertEquals(1, q.size());
+        assertSame(four, q.poll());
+        assertNull(q.poll());
+        checkEmpty(q);
     }
 
-    private LinkedTransferQueue populatedQueue(
-            int n) {
-        LinkedTransferQueue q = new LinkedTransferQueue();
-        assertTrue(q.isEmpty());
-        int remainingCapacity = q.remainingCapacity();
-        for (int i = 0; i <
-                n; i++) {
+    private LinkedTransferQueue<Integer> populatedQueue(int n) {
+        LinkedTransferQueue<Integer> q = new LinkedTransferQueue<Integer>();
+        checkEmpty(q);
+        for (int i = 0; i < n; i++) {
+            assertEquals(i, q.size());
             assertTrue(q.offer(i));
+            assertEquals(Integer.MAX_VALUE, q.remainingCapacity());
         }
-
         assertFalse(q.isEmpty());
-        assertEquals(remainingCapacity, q.remainingCapacity());
-        assertEquals(n, q.size());
         return q;
     }
 
-    private static class ConsumerObserver {
-
-        private int waitingConsumers;
-
-        private ConsumerObserver() {
-        }
-
-        private void setWaitingConsumer(int i) {
-            this.waitingConsumers = i;
-        }
-
-        private int getWaitingConsumers() {
-            return waitingConsumers;
+    /**
+     * remove(null), contains(null) always return false
+     */
+    public void testNeverContainsNull() {
+        Collection<?>[] qs = {
+            new LinkedTransferQueue<Object>(),
+            populatedQueue(2),
+        };
+
+        for (Collection<?> q : qs) {
+            assertFalse(q.contains(null));
+            assertFalse(q.remove(null));
         }
     }
 }