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      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
      4  * http://creativecommons.org/publicdomain/zero/1.0/
      5  */
      6 
      7 package jsr166;
      8 
      9 import junit.framework.*;
     10 import java.util.Arrays;
     11 import java.util.BitSet;
     12 import java.util.Collection;
     13 import java.util.Comparator;
     14 import java.util.Iterator;
     15 import java.util.NavigableSet;
     16 import java.util.NoSuchElementException;
     17 import java.util.Random;
     18 import java.util.Set;
     19 import java.util.SortedSet;
     20 import java.util.concurrent.ConcurrentSkipListSet;
     21 
     22 public class ConcurrentSkipListSubSetTest extends JSR166TestCase {
     23 
     24     static class MyReverseComparator implements Comparator {
     25         public int compare(Object x, Object y) {
     26             return ((Comparable)y).compareTo(x);
     27         }
     28     }
     29 
     30     /**
     31      * Returns a new set of given size containing consecutive
     32      * Integers 0 ... n.
     33      */
     34     private NavigableSet<Integer> populatedSet(int n) {
     35         ConcurrentSkipListSet<Integer> q =
     36             new ConcurrentSkipListSet<Integer>();
     37         assertTrue(q.isEmpty());
     38 
     39         for (int i = n-1; i >= 0; i-=2)
     40             assertTrue(q.add(new Integer(i)));
     41         for (int i = (n & 1); i < n; i+=2)
     42             assertTrue(q.add(new Integer(i)));
     43         assertTrue(q.add(new Integer(-n)));
     44         assertTrue(q.add(new Integer(n)));
     45         NavigableSet s = q.subSet(new Integer(0), true, new Integer(n), false);
     46         assertFalse(s.isEmpty());
     47         assertEquals(n, s.size());
     48         return s;
     49     }
     50 
     51     /**
     52      * Returns a new set of first 5 ints.
     53      */
     54     private NavigableSet set5() {
     55         ConcurrentSkipListSet q = new ConcurrentSkipListSet();
     56         assertTrue(q.isEmpty());
     57         q.add(one);
     58         q.add(two);
     59         q.add(three);
     60         q.add(four);
     61         q.add(five);
     62         q.add(zero);
     63         q.add(seven);
     64         NavigableSet s = q.subSet(one, true, seven, false);
     65         assertEquals(5, s.size());
     66         return s;
     67     }
     68 
     69     /**
     70      * Returns a new set of first 5 negative ints.
     71      */
     72     private NavigableSet dset5() {
     73         ConcurrentSkipListSet q = new ConcurrentSkipListSet();
     74         assertTrue(q.isEmpty());
     75         q.add(m1);
     76         q.add(m2);
     77         q.add(m3);
     78         q.add(m4);
     79         q.add(m5);
     80         NavigableSet s = q.descendingSet();
     81         assertEquals(5, s.size());
     82         return s;
     83     }
     84 
     85     private static NavigableSet set0() {
     86         ConcurrentSkipListSet set = new ConcurrentSkipListSet();
     87         assertTrue(set.isEmpty());
     88         return set.tailSet(m1, true);
     89     }
     90 
     91     private static NavigableSet dset0() {
     92         ConcurrentSkipListSet set = new ConcurrentSkipListSet();
     93         assertTrue(set.isEmpty());
     94         return set;
     95     }
     96 
     97     /**
     98      * A new set has unbounded capacity
     99      */
    100     public void testConstructor1() {
    101         assertEquals(0, set0().size());
    102     }
    103 
    104     /**
    105      * isEmpty is true before add, false after
    106      */
    107     public void testEmpty() {
    108         NavigableSet q = set0();
    109         assertTrue(q.isEmpty());
    110         q.add(new Integer(1));
    111         assertFalse(q.isEmpty());
    112         q.add(new Integer(2));
    113         q.pollFirst();
    114         q.pollFirst();
    115         assertTrue(q.isEmpty());
    116     }
    117 
    118     /**
    119      * size changes when elements added and removed
    120      */
    121     public void testSize() {
    122         NavigableSet q = populatedSet(SIZE);
    123         for (int i = 0; i < SIZE; ++i) {
    124             assertEquals(SIZE-i, q.size());
    125             q.pollFirst();
    126         }
    127         for (int i = 0; i < SIZE; ++i) {
    128             assertEquals(i, q.size());
    129             q.add(new Integer(i));
    130         }
    131     }
    132 
    133     /**
    134      * add(null) throws NPE
    135      */
    136     public void testAddNull() {
    137         try {
    138             NavigableSet q = set0();
    139             q.add(null);
    140             shouldThrow();
    141         } catch (NullPointerException success) {}
    142     }
    143 
    144     /**
    145      * Add of comparable element succeeds
    146      */
    147     public void testAdd() {
    148         NavigableSet q = set0();
    149         assertTrue(q.add(six));
    150     }
    151 
    152     /**
    153      * Add of duplicate element fails
    154      */
    155     public void testAddDup() {
    156         NavigableSet q = set0();
    157         assertTrue(q.add(six));
    158         assertFalse(q.add(six));
    159     }
    160 
    161     /**
    162      * Add of non-Comparable throws CCE
    163      */
    164     public void testAddNonComparable() {
    165         try {
    166             NavigableSet q = set0();
    167             q.add(new Object());
    168             q.add(new Object());
    169             q.add(new Object());
    170             shouldThrow();
    171         } catch (ClassCastException success) {}
    172     }
    173 
    174     /**
    175      * addAll(null) throws NPE
    176      */
    177     public void testAddAll1() {
    178         try {
    179             NavigableSet q = set0();
    180             q.addAll(null);
    181             shouldThrow();
    182         } catch (NullPointerException success) {}
    183     }
    184 
    185     /**
    186      * addAll of a collection with null elements throws NPE
    187      */
    188     public void testAddAll2() {
    189         try {
    190             NavigableSet q = set0();
    191             Integer[] ints = new Integer[SIZE];
    192             q.addAll(Arrays.asList(ints));
    193             shouldThrow();
    194         } catch (NullPointerException success) {}
    195     }
    196 
    197     /**
    198      * addAll of a collection with any null elements throws NPE after
    199      * possibly adding some elements
    200      */
    201     public void testAddAll3() {
    202         try {
    203             NavigableSet q = set0();
    204             Integer[] ints = new Integer[SIZE];
    205             for (int i = 0; i < SIZE-1; ++i)
    206                 ints[i] = new Integer(i+SIZE);
    207             q.addAll(Arrays.asList(ints));
    208             shouldThrow();
    209         } catch (NullPointerException success) {}
    210     }
    211 
    212     /**
    213      * Set contains all elements of successful addAll
    214      */
    215     public void testAddAll5() {
    216         Integer[] empty = new Integer[0];
    217         Integer[] ints = new Integer[SIZE];
    218         for (int i = 0; i < SIZE; ++i)
    219             ints[i] = new Integer(SIZE-1- i);
    220         NavigableSet q = set0();
    221         assertFalse(q.addAll(Arrays.asList(empty)));
    222         assertTrue(q.addAll(Arrays.asList(ints)));
    223         for (int i = 0; i < SIZE; ++i)
    224             assertEquals(new Integer(i), q.pollFirst());
    225     }
    226 
    227     /**
    228      * poll succeeds unless empty
    229      */
    230     public void testPoll() {
    231         NavigableSet q = populatedSet(SIZE);
    232         for (int i = 0; i < SIZE; ++i) {
    233             assertEquals(i, q.pollFirst());
    234         }
    235         assertNull(q.pollFirst());
    236     }
    237 
    238     /**
    239      * remove(x) removes x and returns true if present
    240      */
    241     public void testRemoveElement() {
    242         NavigableSet q = populatedSet(SIZE);
    243         for (int i = 1; i < SIZE; i+=2) {
    244             assertTrue(q.contains(i));
    245             assertTrue(q.remove(i));
    246             assertFalse(q.contains(i));
    247             assertTrue(q.contains(i-1));
    248         }
    249         for (int i = 0; i < SIZE; i+=2) {
    250             assertTrue(q.contains(i));
    251             assertTrue(q.remove(i));
    252             assertFalse(q.contains(i));
    253             assertFalse(q.remove(i+1));
    254             assertFalse(q.contains(i+1));
    255         }
    256         assertTrue(q.isEmpty());
    257     }
    258 
    259     /**
    260      * contains(x) reports true when elements added but not yet removed
    261      */
    262     public void testContains() {
    263         NavigableSet q = populatedSet(SIZE);
    264         for (int i = 0; i < SIZE; ++i) {
    265             assertTrue(q.contains(new Integer(i)));
    266             q.pollFirst();
    267             assertFalse(q.contains(new Integer(i)));
    268         }
    269     }
    270 
    271     /**
    272      * clear removes all elements
    273      */
    274     public void testClear() {
    275         NavigableSet q = populatedSet(SIZE);
    276         q.clear();
    277         assertTrue(q.isEmpty());
    278         assertEquals(0, q.size());
    279         q.add(new Integer(1));
    280         assertFalse(q.isEmpty());
    281         q.clear();
    282         assertTrue(q.isEmpty());
    283     }
    284 
    285     /**
    286      * containsAll(c) is true when c contains a subset of elements
    287      */
    288     public void testContainsAll() {
    289         NavigableSet q = populatedSet(SIZE);
    290         NavigableSet p = set0();
    291         for (int i = 0; i < SIZE; ++i) {
    292             assertTrue(q.containsAll(p));
    293             assertFalse(p.containsAll(q));
    294             p.add(new Integer(i));
    295         }
    296         assertTrue(p.containsAll(q));
    297     }
    298 
    299     /**
    300      * retainAll(c) retains only those elements of c and reports true if changed
    301      */
    302     public void testRetainAll() {
    303         NavigableSet q = populatedSet(SIZE);
    304         NavigableSet p = populatedSet(SIZE);
    305         for (int i = 0; i < SIZE; ++i) {
    306             boolean changed = q.retainAll(p);
    307             if (i == 0)
    308                 assertFalse(changed);
    309             else
    310                 assertTrue(changed);
    311 
    312             assertTrue(q.containsAll(p));
    313             assertEquals(SIZE-i, q.size());
    314             p.pollFirst();
    315         }
    316     }
    317 
    318     /**
    319      * removeAll(c) removes only those elements of c and reports true if changed
    320      */
    321     public void testRemoveAll() {
    322         for (int i = 1; i < SIZE; ++i) {
    323             NavigableSet q = populatedSet(SIZE);
    324             NavigableSet p = populatedSet(i);
    325             assertTrue(q.removeAll(p));
    326             assertEquals(SIZE-i, q.size());
    327             for (int j = 0; j < i; ++j) {
    328                 Integer I = (Integer)(p.pollFirst());
    329                 assertFalse(q.contains(I));
    330             }
    331         }
    332     }
    333 
    334     /**
    335      * lower returns preceding element
    336      */
    337     public void testLower() {
    338         NavigableSet q = set5();
    339         Object e1 = q.lower(three);
    340         assertEquals(two, e1);
    341 
    342         Object e2 = q.lower(six);
    343         assertEquals(five, e2);
    344 
    345         Object e3 = q.lower(one);
    346         assertNull(e3);
    347 
    348         Object e4 = q.lower(zero);
    349         assertNull(e4);
    350     }
    351 
    352     /**
    353      * higher returns next element
    354      */
    355     public void testHigher() {
    356         NavigableSet q = set5();
    357         Object e1 = q.higher(three);
    358         assertEquals(four, e1);
    359 
    360         Object e2 = q.higher(zero);
    361         assertEquals(one, e2);
    362 
    363         Object e3 = q.higher(five);
    364         assertNull(e3);
    365 
    366         Object e4 = q.higher(six);
    367         assertNull(e4);
    368     }
    369 
    370     /**
    371      * floor returns preceding element
    372      */
    373     public void testFloor() {
    374         NavigableSet q = set5();
    375         Object e1 = q.floor(three);
    376         assertEquals(three, e1);
    377 
    378         Object e2 = q.floor(six);
    379         assertEquals(five, e2);
    380 
    381         Object e3 = q.floor(one);
    382         assertEquals(one, e3);
    383 
    384         Object e4 = q.floor(zero);
    385         assertNull(e4);
    386     }
    387 
    388     /**
    389      * ceiling returns next element
    390      */
    391     public void testCeiling() {
    392         NavigableSet q = set5();
    393         Object e1 = q.ceiling(three);
    394         assertEquals(three, e1);
    395 
    396         Object e2 = q.ceiling(zero);
    397         assertEquals(one, e2);
    398 
    399         Object e3 = q.ceiling(five);
    400         assertEquals(five, e3);
    401 
    402         Object e4 = q.ceiling(six);
    403         assertNull(e4);
    404     }
    405 
    406     /**
    407      * toArray contains all elements in sorted order
    408      */
    409     public void testToArray() {
    410         NavigableSet q = populatedSet(SIZE);
    411         Object[] o = q.toArray();
    412         for (int i = 0; i < o.length; i++)
    413             assertSame(o[i], q.pollFirst());
    414     }
    415 
    416     /**
    417      * toArray(a) contains all elements in sorted order
    418      */
    419     public void testToArray2() {
    420         NavigableSet<Integer> q = populatedSet(SIZE);
    421         Integer[] ints = new Integer[SIZE];
    422         Integer[] array = q.toArray(ints);
    423         assertSame(ints, array);
    424         for (int i = 0; i < ints.length; i++)
    425             assertSame(ints[i], q.pollFirst());
    426     }
    427 
    428     /**
    429      * iterator iterates through all elements
    430      */
    431     public void testIterator() {
    432         NavigableSet q = populatedSet(SIZE);
    433         int i = 0;
    434         Iterator it = q.iterator();
    435         while (it.hasNext()) {
    436             assertTrue(q.contains(it.next()));
    437             ++i;
    438         }
    439         assertEquals(i, SIZE);
    440     }
    441 
    442     /**
    443      * iterator of empty set has no elements
    444      */
    445     public void testEmptyIterator() {
    446         NavigableSet q = set0();
    447         int i = 0;
    448         Iterator it = q.iterator();
    449         while (it.hasNext()) {
    450             assertTrue(q.contains(it.next()));
    451             ++i;
    452         }
    453         assertEquals(0, i);
    454     }
    455 
    456     /**
    457      * iterator.remove removes current element
    458      */
    459     public void testIteratorRemove() {
    460         final NavigableSet q = set0();
    461         q.add(new Integer(2));
    462         q.add(new Integer(1));
    463         q.add(new Integer(3));
    464 
    465         Iterator it = q.iterator();
    466         it.next();
    467         it.remove();
    468 
    469         it = q.iterator();
    470         assertEquals(it.next(), new Integer(2));
    471         assertEquals(it.next(), new Integer(3));
    472         assertFalse(it.hasNext());
    473     }
    474 
    475     /**
    476      * toString contains toStrings of elements
    477      */
    478     public void testToString() {
    479         NavigableSet q = populatedSet(SIZE);
    480         String s = q.toString();
    481         for (int i = 0; i < SIZE; ++i) {
    482             assertTrue(s.contains(String.valueOf(i)));
    483         }
    484     }
    485 
    486     /**
    487      * A deserialized serialized set has same elements
    488      */
    489     public void testSerialization() throws Exception {
    490         NavigableSet x = populatedSet(SIZE);
    491         NavigableSet y = serialClone(x);
    492 
    493         assertNotSame(y, x);
    494         assertEquals(x.size(), y.size());
    495         assertEquals(x, y);
    496         assertEquals(y, x);
    497         while (!x.isEmpty()) {
    498             assertFalse(y.isEmpty());
    499             assertEquals(x.pollFirst(), y.pollFirst());
    500         }
    501         assertTrue(y.isEmpty());
    502     }
    503 
    504     /**
    505      * subSet returns set with keys in requested range
    506      */
    507     public void testSubSetContents() {
    508         NavigableSet set = set5();
    509         SortedSet sm = set.subSet(two, four);
    510         assertEquals(two, sm.first());
    511         assertEquals(three, sm.last());
    512         assertEquals(2, sm.size());
    513         assertFalse(sm.contains(one));
    514         assertTrue(sm.contains(two));
    515         assertTrue(sm.contains(three));
    516         assertFalse(sm.contains(four));
    517         assertFalse(sm.contains(five));
    518         Iterator i = sm.iterator();
    519         Object k;
    520         k = (Integer)(i.next());
    521         assertEquals(two, k);
    522         k = (Integer)(i.next());
    523         assertEquals(three, k);
    524         assertFalse(i.hasNext());
    525         Iterator j = sm.iterator();
    526         j.next();
    527         j.remove();
    528         assertFalse(set.contains(two));
    529         assertEquals(4, set.size());
    530         assertEquals(1, sm.size());
    531         assertEquals(three, sm.first());
    532         assertEquals(three, sm.last());
    533         assertTrue(sm.remove(three));
    534         assertTrue(sm.isEmpty());
    535         assertEquals(3, set.size());
    536     }
    537 
    538     public void testSubSetContents2() {
    539         NavigableSet set = set5();
    540         SortedSet sm = set.subSet(two, three);
    541         assertEquals(1, sm.size());
    542         assertEquals(two, sm.first());
    543         assertEquals(two, sm.last());
    544         assertFalse(sm.contains(one));
    545         assertTrue(sm.contains(two));
    546         assertFalse(sm.contains(three));
    547         assertFalse(sm.contains(four));
    548         assertFalse(sm.contains(five));
    549         Iterator i = sm.iterator();
    550         Object k;
    551         k = (Integer)(i.next());
    552         assertEquals(two, k);
    553         assertFalse(i.hasNext());
    554         Iterator j = sm.iterator();
    555         j.next();
    556         j.remove();
    557         assertFalse(set.contains(two));
    558         assertEquals(4, set.size());
    559         assertEquals(0, sm.size());
    560         assertTrue(sm.isEmpty());
    561         assertFalse(sm.remove(three));
    562         assertEquals(4, set.size());
    563     }
    564 
    565     /**
    566      * headSet returns set with keys in requested range
    567      */
    568     public void testHeadSetContents() {
    569         NavigableSet set = set5();
    570         SortedSet sm = set.headSet(four);
    571         assertTrue(sm.contains(one));
    572         assertTrue(sm.contains(two));
    573         assertTrue(sm.contains(three));
    574         assertFalse(sm.contains(four));
    575         assertFalse(sm.contains(five));
    576         Iterator i = sm.iterator();
    577         Object k;
    578         k = (Integer)(i.next());
    579         assertEquals(one, k);
    580         k = (Integer)(i.next());
    581         assertEquals(two, k);
    582         k = (Integer)(i.next());
    583         assertEquals(three, k);
    584         assertFalse(i.hasNext());
    585         sm.clear();
    586         assertTrue(sm.isEmpty());
    587         assertEquals(2, set.size());
    588         assertEquals(four, set.first());
    589     }
    590 
    591     /**
    592      * tailSet returns set with keys in requested range
    593      */
    594     public void testTailSetContents() {
    595         NavigableSet set = set5();
    596         SortedSet sm = set.tailSet(two);
    597         assertFalse(sm.contains(one));
    598         assertTrue(sm.contains(two));
    599         assertTrue(sm.contains(three));
    600         assertTrue(sm.contains(four));
    601         assertTrue(sm.contains(five));
    602         Iterator i = sm.iterator();
    603         Object k;
    604         k = (Integer)(i.next());
    605         assertEquals(two, k);
    606         k = (Integer)(i.next());
    607         assertEquals(three, k);
    608         k = (Integer)(i.next());
    609         assertEquals(four, k);
    610         k = (Integer)(i.next());
    611         assertEquals(five, k);
    612         assertFalse(i.hasNext());
    613 
    614         SortedSet ssm = sm.tailSet(four);
    615         assertEquals(four, ssm.first());
    616         assertEquals(five, ssm.last());
    617         assertTrue(ssm.remove(four));
    618         assertEquals(1, ssm.size());
    619         assertEquals(3, sm.size());
    620         assertEquals(4, set.size());
    621     }
    622 
    623     /**
    624      * size changes when elements added and removed
    625      */
    626     public void testDescendingSize() {
    627         NavigableSet q = populatedSet(SIZE);
    628         for (int i = 0; i < SIZE; ++i) {
    629             assertEquals(SIZE-i, q.size());
    630             q.pollFirst();
    631         }
    632         for (int i = 0; i < SIZE; ++i) {
    633             assertEquals(i, q.size());
    634             q.add(new Integer(i));
    635         }
    636     }
    637 
    638     /**
    639      * add(null) throws NPE
    640      */
    641     public void testDescendingAddNull() {
    642         try {
    643             NavigableSet q = dset0();
    644             q.add(null);
    645             shouldThrow();
    646         } catch (NullPointerException success) {}
    647     }
    648 
    649     /**
    650      * Add of comparable element succeeds
    651      */
    652     public void testDescendingAdd() {
    653         NavigableSet q = dset0();
    654         assertTrue(q.add(m6));
    655     }
    656 
    657     /**
    658      * Add of duplicate element fails
    659      */
    660     public void testDescendingAddDup() {
    661         NavigableSet q = dset0();
    662         assertTrue(q.add(m6));
    663         assertFalse(q.add(m6));
    664     }
    665 
    666     /**
    667      * Add of non-Comparable throws CCE
    668      */
    669     public void testDescendingAddNonComparable() {
    670         try {
    671             NavigableSet q = dset0();
    672             q.add(new Object());
    673             q.add(new Object());
    674             q.add(new Object());
    675             shouldThrow();
    676         } catch (ClassCastException success) {}
    677     }
    678 
    679     /**
    680      * addAll(null) throws NPE
    681      */
    682     public void testDescendingAddAll1() {
    683         try {
    684             NavigableSet q = dset0();
    685             q.addAll(null);
    686             shouldThrow();
    687         } catch (NullPointerException success) {}
    688     }
    689 
    690     /**
    691      * addAll of a collection with null elements throws NPE
    692      */
    693     public void testDescendingAddAll2() {
    694         try {
    695             NavigableSet q = dset0();
    696             Integer[] ints = new Integer[SIZE];
    697             q.addAll(Arrays.asList(ints));
    698             shouldThrow();
    699         } catch (NullPointerException success) {}
    700     }
    701 
    702     /**
    703      * addAll of a collection with any null elements throws NPE after
    704      * possibly adding some elements
    705      */
    706     public void testDescendingAddAll3() {
    707         try {
    708             NavigableSet q = dset0();
    709             Integer[] ints = new Integer[SIZE];
    710             for (int i = 0; i < SIZE-1; ++i)
    711                 ints[i] = new Integer(i+SIZE);
    712             q.addAll(Arrays.asList(ints));
    713             shouldThrow();
    714         } catch (NullPointerException success) {}
    715     }
    716 
    717     /**
    718      * Set contains all elements of successful addAll
    719      */
    720     public void testDescendingAddAll5() {
    721         Integer[] empty = new Integer[0];
    722         Integer[] ints = new Integer[SIZE];
    723         for (int i = 0; i < SIZE; ++i)
    724             ints[i] = new Integer(SIZE-1- i);
    725         NavigableSet q = dset0();
    726         assertFalse(q.addAll(Arrays.asList(empty)));
    727         assertTrue(q.addAll(Arrays.asList(ints)));
    728         for (int i = 0; i < SIZE; ++i)
    729             assertEquals(new Integer(i), q.pollFirst());
    730     }
    731 
    732     /**
    733      * poll succeeds unless empty
    734      */
    735     public void testDescendingPoll() {
    736         NavigableSet q = populatedSet(SIZE);
    737         for (int i = 0; i < SIZE; ++i) {
    738             assertEquals(i, q.pollFirst());
    739         }
    740         assertNull(q.pollFirst());
    741     }
    742 
    743     /**
    744      * remove(x) removes x and returns true if present
    745      */
    746     public void testDescendingRemoveElement() {
    747         NavigableSet q = populatedSet(SIZE);
    748         for (int i = 1; i < SIZE; i+=2) {
    749             assertTrue(q.remove(new Integer(i)));
    750         }
    751         for (int i = 0; i < SIZE; i+=2) {
    752             assertTrue(q.remove(new Integer(i)));
    753             assertFalse(q.remove(new Integer(i+1)));
    754         }
    755         assertTrue(q.isEmpty());
    756     }
    757 
    758     /**
    759      * contains(x) reports true when elements added but not yet removed
    760      */
    761     public void testDescendingContains() {
    762         NavigableSet q = populatedSet(SIZE);
    763         for (int i = 0; i < SIZE; ++i) {
    764             assertTrue(q.contains(new Integer(i)));
    765             q.pollFirst();
    766             assertFalse(q.contains(new Integer(i)));
    767         }
    768     }
    769 
    770     /**
    771      * clear removes all elements
    772      */
    773     public void testDescendingClear() {
    774         NavigableSet q = populatedSet(SIZE);
    775         q.clear();
    776         assertTrue(q.isEmpty());
    777         assertEquals(0, q.size());
    778         q.add(new Integer(1));
    779         assertFalse(q.isEmpty());
    780         q.clear();
    781         assertTrue(q.isEmpty());
    782     }
    783 
    784     /**
    785      * containsAll(c) is true when c contains a subset of elements
    786      */
    787     public void testDescendingContainsAll() {
    788         NavigableSet q = populatedSet(SIZE);
    789         NavigableSet p = dset0();
    790         for (int i = 0; i < SIZE; ++i) {
    791             assertTrue(q.containsAll(p));
    792             assertFalse(p.containsAll(q));
    793             p.add(new Integer(i));
    794         }
    795         assertTrue(p.containsAll(q));
    796     }
    797 
    798     /**
    799      * retainAll(c) retains only those elements of c and reports true if changed
    800      */
    801     public void testDescendingRetainAll() {
    802         NavigableSet q = populatedSet(SIZE);
    803         NavigableSet p = populatedSet(SIZE);
    804         for (int i = 0; i < SIZE; ++i) {
    805             boolean changed = q.retainAll(p);
    806             if (i == 0)
    807                 assertFalse(changed);
    808             else
    809                 assertTrue(changed);
    810 
    811             assertTrue(q.containsAll(p));
    812             assertEquals(SIZE-i, q.size());
    813             p.pollFirst();
    814         }
    815     }
    816 
    817     /**
    818      * removeAll(c) removes only those elements of c and reports true if changed
    819      */
    820     public void testDescendingRemoveAll() {
    821         for (int i = 1; i < SIZE; ++i) {
    822             NavigableSet q = populatedSet(SIZE);
    823             NavigableSet p = populatedSet(i);
    824             assertTrue(q.removeAll(p));
    825             assertEquals(SIZE-i, q.size());
    826             for (int j = 0; j < i; ++j) {
    827                 Integer I = (Integer)(p.pollFirst());
    828                 assertFalse(q.contains(I));
    829             }
    830         }
    831     }
    832 
    833     /**
    834      * lower returns preceding element
    835      */
    836     public void testDescendingLower() {
    837         NavigableSet q = dset5();
    838         Object e1 = q.lower(m3);
    839         assertEquals(m2, e1);
    840 
    841         Object e2 = q.lower(m6);
    842         assertEquals(m5, e2);
    843 
    844         Object e3 = q.lower(m1);
    845         assertNull(e3);
    846 
    847         Object e4 = q.lower(zero);
    848         assertNull(e4);
    849     }
    850 
    851     /**
    852      * higher returns next element
    853      */
    854     public void testDescendingHigher() {
    855         NavigableSet q = dset5();
    856         Object e1 = q.higher(m3);
    857         assertEquals(m4, e1);
    858 
    859         Object e2 = q.higher(zero);
    860         assertEquals(m1, e2);
    861 
    862         Object e3 = q.higher(m5);
    863         assertNull(e3);
    864 
    865         Object e4 = q.higher(m6);
    866         assertNull(e4);
    867     }
    868 
    869     /**
    870      * floor returns preceding element
    871      */
    872     public void testDescendingFloor() {
    873         NavigableSet q = dset5();
    874         Object e1 = q.floor(m3);
    875         assertEquals(m3, e1);
    876 
    877         Object e2 = q.floor(m6);
    878         assertEquals(m5, e2);
    879 
    880         Object e3 = q.floor(m1);
    881         assertEquals(m1, e3);
    882 
    883         Object e4 = q.floor(zero);
    884         assertNull(e4);
    885     }
    886 
    887     /**
    888      * ceiling returns next element
    889      */
    890     public void testDescendingCeiling() {
    891         NavigableSet q = dset5();
    892         Object e1 = q.ceiling(m3);
    893         assertEquals(m3, e1);
    894 
    895         Object e2 = q.ceiling(zero);
    896         assertEquals(m1, e2);
    897 
    898         Object e3 = q.ceiling(m5);
    899         assertEquals(m5, e3);
    900 
    901         Object e4 = q.ceiling(m6);
    902         assertNull(e4);
    903     }
    904 
    905     /**
    906      * toArray contains all elements
    907      */
    908     public void testDescendingToArray() {
    909         NavigableSet q = populatedSet(SIZE);
    910         Object[] o = q.toArray();
    911         Arrays.sort(o);
    912         for (int i = 0; i < o.length; i++)
    913             assertEquals(o[i], q.pollFirst());
    914     }
    915 
    916     /**
    917      * toArray(a) contains all elements
    918      */
    919     public void testDescendingToArray2() {
    920         NavigableSet q = populatedSet(SIZE);
    921         Integer[] ints = new Integer[SIZE];
    922         assertSame(ints, q.toArray(ints));
    923         Arrays.sort(ints);
    924         for (int i = 0; i < ints.length; i++)
    925             assertEquals(ints[i], q.pollFirst());
    926     }
    927 
    928     /**
    929      * iterator iterates through all elements
    930      */
    931     public void testDescendingIterator() {
    932         NavigableSet q = populatedSet(SIZE);
    933         int i = 0;
    934         Iterator it = q.iterator();
    935         while (it.hasNext()) {
    936             assertTrue(q.contains(it.next()));
    937             ++i;
    938         }
    939         assertEquals(i, SIZE);
    940     }
    941 
    942     /**
    943      * iterator of empty set has no elements
    944      */
    945     public void testDescendingEmptyIterator() {
    946         NavigableSet q = dset0();
    947         int i = 0;
    948         Iterator it = q.iterator();
    949         while (it.hasNext()) {
    950             assertTrue(q.contains(it.next()));
    951             ++i;
    952         }
    953         assertEquals(0, i);
    954     }
    955 
    956     /**
    957      * iterator.remove removes current element
    958      */
    959     public void testDescendingIteratorRemove() {
    960         final NavigableSet q = dset0();
    961         q.add(new Integer(2));
    962         q.add(new Integer(1));
    963         q.add(new Integer(3));
    964 
    965         Iterator it = q.iterator();
    966         it.next();
    967         it.remove();
    968 
    969         it = q.iterator();
    970         assertEquals(it.next(), new Integer(2));
    971         assertEquals(it.next(), new Integer(3));
    972         assertFalse(it.hasNext());
    973     }
    974 
    975     /**
    976      * toString contains toStrings of elements
    977      */
    978     public void testDescendingToString() {
    979         NavigableSet q = populatedSet(SIZE);
    980         String s = q.toString();
    981         for (int i = 0; i < SIZE; ++i) {
    982             assertTrue(s.contains(String.valueOf(i)));
    983         }
    984     }
    985 
    986     /**
    987      * A deserialized serialized set has same elements
    988      */
    989     public void testDescendingSerialization() throws Exception {
    990         NavigableSet x = dset5();
    991         NavigableSet y = serialClone(x);
    992 
    993         assertNotSame(y, x);
    994         assertEquals(x.size(), y.size());
    995         assertEquals(x, y);
    996         assertEquals(y, x);
    997         while (!x.isEmpty()) {
    998             assertFalse(y.isEmpty());
    999             assertEquals(x.pollFirst(), y.pollFirst());
   1000         }
   1001         assertTrue(y.isEmpty());
   1002     }
   1003 
   1004     /**
   1005      * subSet returns set with keys in requested range
   1006      */
   1007     public void testDescendingSubSetContents() {
   1008         NavigableSet set = dset5();
   1009         SortedSet sm = set.subSet(m2, m4);
   1010         assertEquals(m2, sm.first());
   1011         assertEquals(m3, sm.last());
   1012         assertEquals(2, sm.size());
   1013         assertFalse(sm.contains(m1));
   1014         assertTrue(sm.contains(m2));
   1015         assertTrue(sm.contains(m3));
   1016         assertFalse(sm.contains(m4));
   1017         assertFalse(sm.contains(m5));
   1018         Iterator i = sm.iterator();
   1019         Object k;
   1020         k = (Integer)(i.next());
   1021         assertEquals(m2, k);
   1022         k = (Integer)(i.next());
   1023         assertEquals(m3, k);
   1024         assertFalse(i.hasNext());
   1025         Iterator j = sm.iterator();
   1026         j.next();
   1027         j.remove();
   1028         assertFalse(set.contains(m2));
   1029         assertEquals(4, set.size());
   1030         assertEquals(1, sm.size());
   1031         assertEquals(m3, sm.first());
   1032         assertEquals(m3, sm.last());
   1033         assertTrue(sm.remove(m3));
   1034         assertTrue(sm.isEmpty());
   1035         assertEquals(3, set.size());
   1036     }
   1037 
   1038     public void testDescendingSubSetContents2() {
   1039         NavigableSet set = dset5();
   1040         SortedSet sm = set.subSet(m2, m3);
   1041         assertEquals(1, sm.size());
   1042         assertEquals(m2, sm.first());
   1043         assertEquals(m2, sm.last());
   1044         assertFalse(sm.contains(m1));
   1045         assertTrue(sm.contains(m2));
   1046         assertFalse(sm.contains(m3));
   1047         assertFalse(sm.contains(m4));
   1048         assertFalse(sm.contains(m5));
   1049         Iterator i = sm.iterator();
   1050         Object k;
   1051         k = (Integer)(i.next());
   1052         assertEquals(m2, k);
   1053         assertFalse(i.hasNext());
   1054         Iterator j = sm.iterator();
   1055         j.next();
   1056         j.remove();
   1057         assertFalse(set.contains(m2));
   1058         assertEquals(4, set.size());
   1059         assertEquals(0, sm.size());
   1060         assertTrue(sm.isEmpty());
   1061         assertFalse(sm.remove(m3));
   1062         assertEquals(4, set.size());
   1063     }
   1064 
   1065     /**
   1066      * headSet returns set with keys in requested range
   1067      */
   1068     public void testDescendingHeadSetContents() {
   1069         NavigableSet set = dset5();
   1070         SortedSet sm = set.headSet(m4);
   1071         assertTrue(sm.contains(m1));
   1072         assertTrue(sm.contains(m2));
   1073         assertTrue(sm.contains(m3));
   1074         assertFalse(sm.contains(m4));
   1075         assertFalse(sm.contains(m5));
   1076         Iterator i = sm.iterator();
   1077         Object k;
   1078         k = (Integer)(i.next());
   1079         assertEquals(m1, k);
   1080         k = (Integer)(i.next());
   1081         assertEquals(m2, k);
   1082         k = (Integer)(i.next());
   1083         assertEquals(m3, k);
   1084         assertFalse(i.hasNext());
   1085         sm.clear();
   1086         assertTrue(sm.isEmpty());
   1087         assertEquals(2, set.size());
   1088         assertEquals(m4, set.first());
   1089     }
   1090 
   1091     /**
   1092      * tailSet returns set with keys in requested range
   1093      */
   1094     public void testDescendingTailSetContents() {
   1095         NavigableSet set = dset5();
   1096         SortedSet sm = set.tailSet(m2);
   1097         assertFalse(sm.contains(m1));
   1098         assertTrue(sm.contains(m2));
   1099         assertTrue(sm.contains(m3));
   1100         assertTrue(sm.contains(m4));
   1101         assertTrue(sm.contains(m5));
   1102         Iterator i = sm.iterator();
   1103         Object k;
   1104         k = (Integer)(i.next());
   1105         assertEquals(m2, k);
   1106         k = (Integer)(i.next());
   1107         assertEquals(m3, k);
   1108         k = (Integer)(i.next());
   1109         assertEquals(m4, k);
   1110         k = (Integer)(i.next());
   1111         assertEquals(m5, k);
   1112         assertFalse(i.hasNext());
   1113 
   1114         SortedSet ssm = sm.tailSet(m4);
   1115         assertEquals(m4, ssm.first());
   1116         assertEquals(m5, ssm.last());
   1117         assertTrue(ssm.remove(m4));
   1118         assertEquals(1, ssm.size());
   1119         assertEquals(3, sm.size());
   1120         assertEquals(4, set.size());
   1121     }
   1122 
   1123 }
   1124