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Comparing jsr166/src/test/tck/JSR166TestCase.java (file contents):
Revision 1.203 by jsr166, Thu Sep 15 03:46:19 2016 UTC vs.
Revision 1.232 by jsr166, Mon May 29 19:15:02 2017 UTC

# Line 1 | Line 1
1   /*
2 < * Written by Doug Lea with assistance from members of JCP JSR-166
3 < * Expert Group and released to the public domain, as explained at
2 > * Written by Doug Lea and Martin Buchholz with assistance from
3 > * members of JCP JSR-166 Expert Group and released to the public
4 > * domain, as explained at
5   * http://creativecommons.org/publicdomain/zero/1.0/
6   * Other contributors include Andrew Wright, Jeffrey Hayes,
7   * Pat Fisher, Mike Judd.
# Line 8 | Line 9
9  
10   /*
11   * @test
12 < * @summary JSR-166 tck tests
13 < * @modules java.management
12 > * @summary JSR-166 tck tests, in a number of variations.
13 > *          The first is the conformance testing variant,
14 > *          while others also test implementation details.
15   * @build *
16 < * @run junit/othervm/timeout=1000 -Djsr166.testImplementationDetails=true JSR166TestCase
17 < * @run junit/othervm/timeout=1000 -Djava.util.concurrent.ForkJoinPool.common.parallelism=0 -Djsr166.testImplementationDetails=true JSR166TestCase
18 < * @run junit/othervm/timeout=1000 -Djava.util.concurrent.ForkJoinPool.common.parallelism=1 -Djava.util.secureRandomSeed=true JSR166TestCase
16 > * @modules java.management
17 > * @run junit/othervm/timeout=1000 JSR166TestCase
18 > * @run junit/othervm/timeout=1000
19 > *      --add-opens java.base/java.util.concurrent=ALL-UNNAMED
20 > *      --add-opens java.base/java.lang=ALL-UNNAMED
21 > *      -Djsr166.testImplementationDetails=true
22 > *      JSR166TestCase
23 > * @run junit/othervm/timeout=1000
24 > *      --add-opens java.base/java.util.concurrent=ALL-UNNAMED
25 > *      --add-opens java.base/java.lang=ALL-UNNAMED
26 > *      -Djsr166.testImplementationDetails=true
27 > *      -Djava.util.concurrent.ForkJoinPool.common.parallelism=0
28 > *      JSR166TestCase
29 > * @run junit/othervm/timeout=1000
30 > *      --add-opens java.base/java.util.concurrent=ALL-UNNAMED
31 > *      --add-opens java.base/java.lang=ALL-UNNAMED
32 > *      -Djsr166.testImplementationDetails=true
33 > *      -Djava.util.concurrent.ForkJoinPool.common.parallelism=1
34 > *      -Djava.util.secureRandomSeed=true
35 > *      JSR166TestCase
36 > * @run junit/othervm/timeout=1000/policy=tck.policy
37 > *      --add-opens java.base/java.util.concurrent=ALL-UNNAMED
38 > *      --add-opens java.base/java.lang=ALL-UNNAMED
39 > *      -Djsr166.testImplementationDetails=true
40 > *      JSR166TestCase
41   */
42  
43   import static java.util.concurrent.TimeUnit.MILLISECONDS;
# Line 30 | Line 54 | import java.lang.management.ThreadMXBean
54   import java.lang.reflect.Constructor;
55   import java.lang.reflect.Method;
56   import java.lang.reflect.Modifier;
33 import java.nio.file.Files;
34 import java.nio.file.Paths;
57   import java.security.CodeSource;
58   import java.security.Permission;
59   import java.security.PermissionCollection;
# Line 41 | Line 63 | import java.security.ProtectionDomain;
63   import java.security.SecurityPermission;
64   import java.util.ArrayList;
65   import java.util.Arrays;
66 + import java.util.Collection;
67   import java.util.Collections;
68   import java.util.Date;
69   import java.util.Enumeration;
# Line 65 | Line 88 | import java.util.concurrent.SynchronousQ
88   import java.util.concurrent.ThreadFactory;
89   import java.util.concurrent.ThreadLocalRandom;
90   import java.util.concurrent.ThreadPoolExecutor;
91 + import java.util.concurrent.TimeUnit;
92   import java.util.concurrent.TimeoutException;
93   import java.util.concurrent.atomic.AtomicBoolean;
94   import java.util.concurrent.atomic.AtomicReference;
71 import java.util.regex.Matcher;
95   import java.util.regex.Pattern;
96  
97   import junit.framework.AssertionFailedError;
# Line 278 | Line 301 | public class JSR166TestCase extends Test
301  
302   //     public static String cpuModel() {
303   //         try {
304 < //             Matcher matcher = Pattern.compile("model name\\s*: (.*)")
304 > //             java.util.regex.Matcher matcher
305 > //               = Pattern.compile("model name\\s*: (.*)")
306   //                 .matcher(new String(
307 < //                      Files.readAllBytes(Paths.get("/proc/cpuinfo")), "UTF-8"));
307 > //                     java.nio.file.Files.readAllBytes(
308 > //                         java.nio.file.Paths.get("/proc/cpuinfo")), "UTF-8"));
309   //             matcher.find();
310   //             return matcher.group(1);
311   //         } catch (Exception ex) { return null; }
# Line 447 | Line 472 | public class JSR166TestCase extends Test
472              AbstractQueuedLongSynchronizerTest.suite(),
473              ArrayBlockingQueueTest.suite(),
474              ArrayDequeTest.suite(),
475 +            ArrayListTest.suite(),
476              AtomicBooleanTest.suite(),
477              AtomicIntegerArrayTest.suite(),
478              AtomicIntegerFieldUpdaterTest.suite(),
# Line 469 | Line 495 | public class JSR166TestCase extends Test
495              CopyOnWriteArrayListTest.suite(),
496              CopyOnWriteArraySetTest.suite(),
497              CountDownLatchTest.suite(),
498 +            CountedCompleterTest.suite(),
499              CyclicBarrierTest.suite(),
500              DelayQueueTest.suite(),
501              EntryTest.suite(),
# Line 497 | Line 524 | public class JSR166TestCase extends Test
524              TreeMapTest.suite(),
525              TreeSetTest.suite(),
526              TreeSubMapTest.suite(),
527 <            TreeSubSetTest.suite());
527 >            TreeSubSetTest.suite(),
528 >            VectorTest.suite());
529  
530          // Java8+ test classes
531          if (atLeastJava8()) {
532              String[] java8TestClassNames = {
533 +                "ArrayDeque8Test",
534                  "Atomic8Test",
535                  "CompletableFutureTest",
536                  "ConcurrentHashMap8Test",
537 <                "CountedCompleterTest",
537 >                "CountedCompleter8Test",
538                  "DoubleAccumulatorTest",
539                  "DoubleAdderTest",
540                  "ForkJoinPool8Test",
541                  "ForkJoinTask8Test",
542 +                "LinkedBlockingDeque8Test",
543 +                "LinkedBlockingQueue8Test",
544                  "LongAccumulatorTest",
545                  "LongAdderTest",
546                  "SplittableRandomTest",
# Line 532 | Line 563 | public class JSR166TestCase extends Test
563                  "AtomicReference9Test",
564                  "AtomicReferenceArray9Test",
565                  "ExecutorCompletionService9Test",
566 +                "ForkJoinPool9Test",
567              };
568              addNamedTestClasses(suite, java9TestClassNames);
569          }
# Line 542 | Line 574 | public class JSR166TestCase extends Test
574      /** Returns list of junit-style test method names in given class. */
575      public static ArrayList<String> testMethodNames(Class<?> testClass) {
576          Method[] methods = testClass.getDeclaredMethods();
577 <        ArrayList<String> names = new ArrayList<String>(methods.length);
577 >        ArrayList<String> names = new ArrayList<>(methods.length);
578          for (Method method : methods) {
579              if (method.getName().startsWith("test")
580                  && Modifier.isPublic(method.getModifiers())
# Line 607 | Line 639 | public class JSR166TestCase extends Test
639      public static long MEDIUM_DELAY_MS;
640      public static long LONG_DELAY_MS;
641  
642 +    private static final long RANDOM_TIMEOUT;
643 +    private static final long RANDOM_EXPIRED_TIMEOUT;
644 +    private static final TimeUnit RANDOM_TIMEUNIT;
645 +    static {
646 +        ThreadLocalRandom rnd = ThreadLocalRandom.current();
647 +        long[] timeouts = { Long.MIN_VALUE, -1, 0, 1, Long.MAX_VALUE };
648 +        RANDOM_TIMEOUT = timeouts[rnd.nextInt(timeouts.length)];
649 +        RANDOM_EXPIRED_TIMEOUT = timeouts[rnd.nextInt(3)];
650 +        TimeUnit[] timeUnits = TimeUnit.values();
651 +        RANDOM_TIMEUNIT = timeUnits[rnd.nextInt(timeUnits.length)];
652 +    }
653 +
654 +    /**
655 +     * Returns a timeout for use when any value at all will do.
656 +     */
657 +    static long randomTimeout() { return RANDOM_TIMEOUT; }
658 +
659 +    /**
660 +     * Returns a timeout that means "no waiting", i.e. not positive.
661 +     */
662 +    static long randomExpiredTimeout() { return RANDOM_EXPIRED_TIMEOUT; }
663 +
664 +    /**
665 +     * Returns a random non-null TimeUnit.
666 +     */
667 +    static TimeUnit randomTimeUnit() { return RANDOM_TIMEUNIT; }
668 +
669      /**
670       * Returns the shortest timed delay. This can be scaled up for
671       * slow machines using the jsr166.delay.factor system property,
# Line 627 | Line 686 | public class JSR166TestCase extends Test
686          LONG_DELAY_MS   = SHORT_DELAY_MS * 200;
687      }
688  
689 +    private static final long TIMEOUT_DELAY_MS
690 +        = (long) (12.0 * Math.cbrt(delayFactor));
691 +
692      /**
693 <     * Returns a timeout in milliseconds to be used in tests that
694 <     * verify that operations block or time out.
693 >     * Returns a timeout in milliseconds to be used in tests that verify
694 >     * that operations block or time out.  We want this to be longer
695 >     * than the OS scheduling quantum, but not too long, so don't scale
696 >     * linearly with delayFactor; we use "crazy" cube root instead.
697       */
698 <    long timeoutMillis() {
699 <        return SHORT_DELAY_MS / 4;
698 >    static long timeoutMillis() {
699 >        return TIMEOUT_DELAY_MS;
700      }
701  
702      /**
# Line 648 | Line 712 | public class JSR166TestCase extends Test
712       * The first exception encountered if any threadAssertXXX method fails.
713       */
714      private final AtomicReference<Throwable> threadFailure
715 <        = new AtomicReference<Throwable>(null);
715 >        = new AtomicReference<>(null);
716  
717      /**
718       * Records an exception so that it can be rethrown later in the test
# Line 1027 | Line 1091 | public class JSR166TestCase extends Test
1091      }
1092  
1093      /**
1094 +     * Checks that thread eventually enters the expected blocked thread state.
1095 +     */
1096 +    void assertThreadBlocks(Thread thread, Thread.State expected) {
1097 +        // always sleep at least 1 ms, with high probability avoiding
1098 +        // transitory states
1099 +        for (long retries = LONG_DELAY_MS * 3 / 4; retries-->0; ) {
1100 +            try { delay(1); }
1101 +            catch (InterruptedException fail) {
1102 +                fail("Unexpected InterruptedException");
1103 +            }
1104 +            Thread.State s = thread.getState();
1105 +            if (s == expected)
1106 +                return;
1107 +            else if (s == Thread.State.TERMINATED)
1108 +                fail("Unexpected thread termination");
1109 +        }
1110 +        fail("timed out waiting for thread to enter thread state " + expected);
1111 +    }
1112 +
1113 +    /**
1114       * Checks that thread does not terminate within the default
1115       * millisecond delay of {@code timeoutMillis()}.
1116 +     * TODO: REMOVEME
1117       */
1118      void assertThreadStaysAlive(Thread thread) {
1119          assertThreadStaysAlive(thread, timeoutMillis());
# Line 1036 | Line 1121 | public class JSR166TestCase extends Test
1121  
1122      /**
1123       * Checks that thread does not terminate within the given millisecond delay.
1124 +     * TODO: REMOVEME
1125       */
1126      void assertThreadStaysAlive(Thread thread, long millis) {
1127          try {
# Line 1050 | Line 1136 | public class JSR166TestCase extends Test
1136      /**
1137       * Checks that the threads do not terminate within the default
1138       * millisecond delay of {@code timeoutMillis()}.
1139 +     * TODO: REMOVEME
1140       */
1141      void assertThreadsStayAlive(Thread... threads) {
1142          assertThreadsStayAlive(timeoutMillis(), threads);
# Line 1057 | Line 1144 | public class JSR166TestCase extends Test
1144  
1145      /**
1146       * Checks that the threads do not terminate within the given millisecond delay.
1147 +     * TODO: REMOVEME
1148       */
1149      void assertThreadsStayAlive(long millis, Thread... threads) {
1150          try {
# Line 1107 | Line 1195 | public class JSR166TestCase extends Test
1195      }
1196  
1197      /**
1198 +     * The maximum number of consecutive spurious wakeups we should
1199 +     * tolerate (from APIs like LockSupport.park) before failing a test.
1200 +     */
1201 +    static final int MAX_SPURIOUS_WAKEUPS = 10;
1202 +
1203 +    /**
1204       * The number of elements to place in collections, arrays, etc.
1205       */
1206      public static final int SIZE = 20;
# Line 1210 | Line 1304 | public class JSR166TestCase extends Test
1304          }
1305          public void refresh() {}
1306          public String toString() {
1307 <            List<Permission> ps = new ArrayList<Permission>();
1307 >            List<Permission> ps = new ArrayList<>();
1308              for (Enumeration<Permission> e = perms.elements(); e.hasMoreElements();)
1309                  ps.add(e.nextElement());
1310              return "AdjustablePolicy with permissions " + ps;
# Line 1269 | Line 1363 | public class JSR166TestCase extends Test
1363                  startTime = System.nanoTime();
1364              else if (millisElapsedSince(startTime) > timeoutMillis) {
1365                  threadAssertTrue(thread.isAlive());
1366 <                return;
1366 >                fail("timed out waiting for thread to enter wait state");
1367 >            }
1368 >            Thread.yield();
1369 >        }
1370 >    }
1371 >
1372 >    /**
1373 >     * Spin-waits up to the specified number of milliseconds for the given
1374 >     * thread to enter a wait state: BLOCKED, WAITING, or TIMED_WAITING,
1375 >     * and additionally satisfy the given condition.
1376 >     */
1377 >    void waitForThreadToEnterWaitState(
1378 >        Thread thread, long timeoutMillis, Callable<Boolean> waitingForGodot) {
1379 >        long startTime = 0L;
1380 >        for (;;) {
1381 >            Thread.State s = thread.getState();
1382 >            if (s == Thread.State.BLOCKED ||
1383 >                s == Thread.State.WAITING ||
1384 >                s == Thread.State.TIMED_WAITING) {
1385 >                try {
1386 >                    if (waitingForGodot.call())
1387 >                        return;
1388 >                } catch (Throwable fail) { threadUnexpectedException(fail); }
1389 >            }
1390 >            else if (s == Thread.State.TERMINATED)
1391 >                fail("Unexpected thread termination");
1392 >            else if (startTime == 0L)
1393 >                startTime = System.nanoTime();
1394 >            else if (millisElapsedSince(startTime) > timeoutMillis) {
1395 >                threadAssertTrue(thread.isAlive());
1396 >                fail("timed out waiting for thread to enter wait state");
1397              }
1398              Thread.yield();
1399          }
1400      }
1401  
1402      /**
1403 <     * Waits up to LONG_DELAY_MS for the given thread to enter a wait
1404 <     * state: BLOCKED, WAITING, or TIMED_WAITING.
1403 >     * Spin-waits up to LONG_DELAY_MS milliseconds for the given thread to
1404 >     * enter a wait state: BLOCKED, WAITING, or TIMED_WAITING.
1405       */
1406      void waitForThreadToEnterWaitState(Thread thread) {
1407          waitForThreadToEnterWaitState(thread, LONG_DELAY_MS);
1408      }
1409  
1410      /**
1411 +     * Spin-waits up to LONG_DELAY_MS milliseconds for the given thread to
1412 +     * enter a wait state: BLOCKED, WAITING, or TIMED_WAITING,
1413 +     * and additionally satisfy the given condition.
1414 +     */
1415 +    void waitForThreadToEnterWaitState(
1416 +        Thread thread, Callable<Boolean> waitingForGodot) {
1417 +        waitForThreadToEnterWaitState(thread, LONG_DELAY_MS, waitingForGodot);
1418 +    }
1419 +
1420 +    /**
1421       * Returns the number of milliseconds since time given by
1422       * startNanoTime, which must have been previously returned from a
1423       * call to {@link System#nanoTime()}.
# Line 1535 | Line 1669 | public class JSR166TestCase extends Test
1669          }
1670      }
1671  
1672 +    public void await(CyclicBarrier barrier) {
1673 +        try {
1674 +            barrier.await(LONG_DELAY_MS, MILLISECONDS);
1675 +        } catch (Throwable fail) {
1676 +            threadUnexpectedException(fail);
1677 +        }
1678 +    }
1679 +
1680   //     /**
1681   //      * Spin-waits up to LONG_DELAY_MS until flag becomes true.
1682   //      */
# Line 1558 | Line 1700 | public class JSR166TestCase extends Test
1700          public String call() { throw new NullPointerException(); }
1701      }
1702  
1561    public static class CallableOne implements Callable<Integer> {
1562        public Integer call() { return one; }
1563    }
1564
1565    public class ShortRunnable extends CheckedRunnable {
1566        protected void realRun() throws Throwable {
1567            delay(SHORT_DELAY_MS);
1568        }
1569    }
1570
1571    public class ShortInterruptedRunnable extends CheckedInterruptedRunnable {
1572        protected void realRun() throws InterruptedException {
1573            delay(SHORT_DELAY_MS);
1574        }
1575    }
1576
1577    public class SmallRunnable extends CheckedRunnable {
1578        protected void realRun() throws Throwable {
1579            delay(SMALL_DELAY_MS);
1580        }
1581    }
1582
1703      public class SmallPossiblyInterruptedRunnable extends CheckedRunnable {
1704          protected void realRun() {
1705              try {
# Line 1588 | Line 1708 | public class JSR166TestCase extends Test
1708          }
1709      }
1710  
1591    public class SmallCallable extends CheckedCallable {
1592        protected Object realCall() throws InterruptedException {
1593            delay(SMALL_DELAY_MS);
1594            return Boolean.TRUE;
1595        }
1596    }
1597
1598    public class MediumRunnable extends CheckedRunnable {
1599        protected void realRun() throws Throwable {
1600            delay(MEDIUM_DELAY_MS);
1601        }
1602    }
1603
1604    public class MediumInterruptedRunnable extends CheckedInterruptedRunnable {
1605        protected void realRun() throws InterruptedException {
1606            delay(MEDIUM_DELAY_MS);
1607        }
1608    }
1609
1711      public Runnable possiblyInterruptedRunnable(final long timeoutMillis) {
1712          return new CheckedRunnable() {
1713              protected void realRun() {
# Line 1616 | Line 1717 | public class JSR166TestCase extends Test
1717              }};
1718      }
1719  
1619    public class MediumPossiblyInterruptedRunnable extends CheckedRunnable {
1620        protected void realRun() {
1621            try {
1622                delay(MEDIUM_DELAY_MS);
1623            } catch (InterruptedException ok) {}
1624        }
1625    }
1626
1627    public class LongPossiblyInterruptedRunnable extends CheckedRunnable {
1628        protected void realRun() {
1629            try {
1630                delay(LONG_DELAY_MS);
1631            } catch (InterruptedException ok) {}
1632        }
1633    }
1634
1720      /**
1721       * For use as ThreadFactory in constructors
1722       */
# Line 1645 | Line 1730 | public class JSR166TestCase extends Test
1730          boolean isDone();
1731      }
1732  
1648    public static TrackedRunnable trackedRunnable(final long timeoutMillis) {
1649        return new TrackedRunnable() {
1650                private volatile boolean done = false;
1651                public boolean isDone() { return done; }
1652                public void run() {
1653                    try {
1654                        delay(timeoutMillis);
1655                        done = true;
1656                    } catch (InterruptedException ok) {}
1657                }
1658            };
1659    }
1660
1661    public static class TrackedShortRunnable implements Runnable {
1662        public volatile boolean done = false;
1663        public void run() {
1664            try {
1665                delay(SHORT_DELAY_MS);
1666                done = true;
1667            } catch (InterruptedException ok) {}
1668        }
1669    }
1670
1671    public static class TrackedSmallRunnable implements Runnable {
1672        public volatile boolean done = false;
1673        public void run() {
1674            try {
1675                delay(SMALL_DELAY_MS);
1676                done = true;
1677            } catch (InterruptedException ok) {}
1678        }
1679    }
1680
1681    public static class TrackedMediumRunnable implements Runnable {
1682        public volatile boolean done = false;
1683        public void run() {
1684            try {
1685                delay(MEDIUM_DELAY_MS);
1686                done = true;
1687            } catch (InterruptedException ok) {}
1688        }
1689    }
1690
1691    public static class TrackedLongRunnable implements Runnable {
1692        public volatile boolean done = false;
1693        public void run() {
1694            try {
1695                delay(LONG_DELAY_MS);
1696                done = true;
1697            } catch (InterruptedException ok) {}
1698        }
1699    }
1700
1733      public static class TrackedNoOpRunnable implements Runnable {
1734          public volatile boolean done = false;
1735          public void run() {
# Line 1705 | Line 1737 | public class JSR166TestCase extends Test
1737          }
1738      }
1739  
1708    public static class TrackedCallable implements Callable {
1709        public volatile boolean done = false;
1710        public Object call() {
1711            try {
1712                delay(SMALL_DELAY_MS);
1713                done = true;
1714            } catch (InterruptedException ok) {}
1715            return Boolean.TRUE;
1716        }
1717    }
1718
1740      /**
1741       * Analog of CheckedRunnable for RecursiveAction
1742       */
# Line 1782 | Line 1803 | public class JSR166TestCase extends Test
1803              assertEquals(0, q.size());
1804              assertNull(q.peek());
1805              assertNull(q.poll());
1806 <            assertNull(q.poll(0, MILLISECONDS));
1806 >            assertNull(q.poll(randomExpiredTimeout(), randomTimeUnit()));
1807              assertEquals(q.toString(), "[]");
1808              assertTrue(Arrays.equals(q.toArray(), new Object[0]));
1809              assertFalse(q.iterator().hasNext());
# Line 1823 | Line 1844 | public class JSR166TestCase extends Test
1844          }
1845      }
1846  
1847 +    void assertImmutable(final Object o) {
1848 +        if (o instanceof Collection) {
1849 +            assertThrows(
1850 +                UnsupportedOperationException.class,
1851 +                new Runnable() { public void run() {
1852 +                        ((Collection) o).add(null);}});
1853 +        }
1854 +    }
1855 +
1856      @SuppressWarnings("unchecked")
1857      <T> T serialClone(T o) {
1858          try {
1859              ObjectInputStream ois = new ObjectInputStream
1860                  (new ByteArrayInputStream(serialBytes(o)));
1861              T clone = (T) ois.readObject();
1862 +            if (o == clone) assertImmutable(o);
1863              assertSame(o.getClass(), clone.getClass());
1864              return clone;
1865          } catch (Throwable fail) {
# Line 1837 | Line 1868 | public class JSR166TestCase extends Test
1868          }
1869      }
1870  
1871 +    /**
1872 +     * A version of serialClone that leaves error handling (for
1873 +     * e.g. NotSerializableException) up to the caller.
1874 +     */
1875 +    @SuppressWarnings("unchecked")
1876 +    <T> T serialClonePossiblyFailing(T o)
1877 +        throws ReflectiveOperationException, java.io.IOException {
1878 +        ByteArrayOutputStream bos = new ByteArrayOutputStream();
1879 +        ObjectOutputStream oos = new ObjectOutputStream(bos);
1880 +        oos.writeObject(o);
1881 +        oos.flush();
1882 +        oos.close();
1883 +        ObjectInputStream ois = new ObjectInputStream
1884 +            (new ByteArrayInputStream(bos.toByteArray()));
1885 +        T clone = (T) ois.readObject();
1886 +        if (o == clone) assertImmutable(o);
1887 +        assertSame(o.getClass(), clone.getClass());
1888 +        return clone;
1889 +    }
1890 +
1891 +    /**
1892 +     * If o implements Cloneable and has a public clone method,
1893 +     * returns a clone of o, else null.
1894 +     */
1895 +    @SuppressWarnings("unchecked")
1896 +    <T> T cloneableClone(T o) {
1897 +        if (!(o instanceof Cloneable)) return null;
1898 +        final T clone;
1899 +        try {
1900 +            clone = (T) o.getClass().getMethod("clone").invoke(o);
1901 +        } catch (NoSuchMethodException ok) {
1902 +            return null;
1903 +        } catch (ReflectiveOperationException unexpected) {
1904 +            throw new Error(unexpected);
1905 +        }
1906 +        assertNotSame(o, clone); // not 100% guaranteed by spec
1907 +        assertSame(o.getClass(), clone.getClass());
1908 +        return clone;
1909 +    }
1910 +
1911      public void assertThrows(Class<? extends Throwable> expectedExceptionClass,
1912                               Runnable... throwingActions) {
1913          for (Runnable throwingAction : throwingActions) {

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