jdk/test/java/util/concurrent/tck/TreeSetTest.java
changeset 35394 282c3cb6a0c1
child 41131 87edc8451f8a
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/util/concurrent/tck/TreeSetTest.java	Fri Jan 29 11:44:19 2016 -0800
@@ -0,0 +1,1008 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * 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/publicdomain/zero/1.0/
+ */
+
+import java.util.Arrays;
+import java.util.BitSet;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.NavigableSet;
+import java.util.NoSuchElementException;
+import java.util.Random;
+import java.util.Set;
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+import junit.framework.Test;
+import junit.framework.TestSuite;
+
+public class TreeSetTest extends JSR166TestCase {
+    public static void main(String[] args) {
+        main(suite(), args);
+    }
+    public static Test suite() {
+        return new TestSuite(TreeSetTest.class);
+    }
+
+    static class MyReverseComparator implements Comparator {
+        public int compare(Object x, Object y) {
+            return ((Comparable)y).compareTo(x);
+        }
+    }
+
+    /**
+     * The number of elements to place in collections, arrays, etc.
+     */
+    static final int SIZE = 20;
+
+    /**
+     * Returns a new set of given size containing consecutive
+     * Integers 0 ... n.
+     */
+    private TreeSet<Integer> populatedSet(int n) {
+        TreeSet<Integer> q = new TreeSet<Integer>();
+        assertTrue(q.isEmpty());
+        for (int i = n - 1; i >= 0; i -= 2)
+            assertTrue(q.add(new Integer(i)));
+        for (int i = (n & 1); i < n; i += 2)
+            assertTrue(q.add(new Integer(i)));
+        assertFalse(q.isEmpty());
+        assertEquals(n, q.size());
+        return q;
+    }
+
+    /**
+     * Returns a new set of first 5 ints.
+     */
+    private TreeSet set5() {
+        TreeSet q = new TreeSet();
+        assertTrue(q.isEmpty());
+        q.add(one);
+        q.add(two);
+        q.add(three);
+        q.add(four);
+        q.add(five);
+        assertEquals(5, q.size());
+        return q;
+    }
+
+    /**
+     * A new set has unbounded capacity
+     */
+    public void testConstructor1() {
+        assertEquals(0, new TreeSet().size());
+    }
+
+    /**
+     * Initializing from null Collection throws NPE
+     */
+    public void testConstructor3() {
+        try {
+            new TreeSet((Collection)null);
+            shouldThrow();
+        } catch (NullPointerException success) {}
+    }
+
+    /**
+     * Initializing from Collection of null elements throws NPE
+     */
+    public void testConstructor4() {
+        try {
+            new TreeSet(Arrays.asList(new Integer[SIZE]));
+            shouldThrow();
+        } catch (NullPointerException success) {}
+    }
+
+    /**
+     * Initializing from Collection with some null elements throws NPE
+     */
+    public void testConstructor5() {
+        Integer[] ints = new Integer[SIZE];
+        for (int i = 0; i < SIZE - 1; ++i)
+            ints[i] = new Integer(i);
+        try {
+            new TreeSet(Arrays.asList(ints));
+            shouldThrow();
+        } catch (NullPointerException success) {}
+    }
+
+    /**
+     * Set contains all elements of collection used to initialize
+     */
+    public void testConstructor6() {
+        Integer[] ints = new Integer[SIZE];
+        for (int i = 0; i < SIZE; ++i)
+            ints[i] = new Integer(i);
+        TreeSet q = new TreeSet(Arrays.asList(ints));
+        for (int i = 0; i < SIZE; ++i)
+            assertEquals(ints[i], q.pollFirst());
+    }
+
+    /**
+     * The comparator used in constructor is used
+     */
+    public void testConstructor7() {
+        MyReverseComparator cmp = new MyReverseComparator();
+        TreeSet q = new TreeSet(cmp);
+        assertEquals(cmp, q.comparator());
+        Integer[] ints = new Integer[SIZE];
+        for (int i = 0; i < SIZE; ++i)
+            ints[i] = new Integer(i);
+        q.addAll(Arrays.asList(ints));
+        for (int i = SIZE - 1; i >= 0; --i)
+            assertEquals(ints[i], q.pollFirst());
+    }
+
+    /**
+     * isEmpty is true before add, false after
+     */
+    public void testEmpty() {
+        TreeSet q = new TreeSet();
+        assertTrue(q.isEmpty());
+        q.add(new Integer(1));
+        assertFalse(q.isEmpty());
+        q.add(new Integer(2));
+        q.pollFirst();
+        q.pollFirst();
+        assertTrue(q.isEmpty());
+    }
+
+    /**
+     * size changes when elements added and removed
+     */
+    public void testSize() {
+        TreeSet q = populatedSet(SIZE);
+        for (int i = 0; i < SIZE; ++i) {
+            assertEquals(SIZE - i, q.size());
+            q.pollFirst();
+        }
+        for (int i = 0; i < SIZE; ++i) {
+            assertEquals(i, q.size());
+            q.add(new Integer(i));
+        }
+    }
+
+    /**
+     * add(null) throws NPE if nonempty
+     */
+    public void testAddNull() {
+        TreeSet q = populatedSet(SIZE);
+        try {
+            q.add(null);
+            shouldThrow();
+        } catch (NullPointerException success) {}
+    }
+
+    /**
+     * Add of comparable element succeeds
+     */
+    public void testAdd() {
+        TreeSet q = new TreeSet();
+        assertTrue(q.add(zero));
+        assertTrue(q.add(one));
+    }
+
+    /**
+     * Add of duplicate element fails
+     */
+    public void testAddDup() {
+        TreeSet q = new TreeSet();
+        assertTrue(q.add(zero));
+        assertFalse(q.add(zero));
+    }
+
+    /**
+     * Add of non-Comparable throws CCE
+     */
+    public void testAddNonComparable() {
+        TreeSet q = new TreeSet();
+        try {
+            q.add(new Object());
+            q.add(new Object());
+            shouldThrow();
+        } catch (ClassCastException success) {}
+    }
+
+    /**
+     * addAll(null) throws NPE
+     */
+    public void testAddAll1() {
+        TreeSet q = new TreeSet();
+        try {
+            q.addAll(null);
+            shouldThrow();
+        } catch (NullPointerException success) {}
+    }
+
+    /**
+     * addAll of a collection with null elements throws NPE
+     */
+    public void testAddAll2() {
+        TreeSet q = new TreeSet();
+        Integer[] ints = new Integer[SIZE];
+        try {
+            q.addAll(Arrays.asList(ints));
+            shouldThrow();
+        } catch (NullPointerException success) {}
+    }
+
+    /**
+     * addAll of a collection with any null elements throws NPE after
+     * possibly adding some elements
+     */
+    public void testAddAll3() {
+        TreeSet q = new TreeSet();
+        Integer[] ints = new Integer[SIZE];
+        for (int i = 0; i < SIZE - 1; ++i)
+            ints[i] = new Integer(i);
+        try {
+            q.addAll(Arrays.asList(ints));
+            shouldThrow();
+        } catch (NullPointerException success) {}
+    }
+
+    /**
+     * Set contains all elements of successful addAll
+     */
+    public void testAddAll5() {
+        Integer[] empty = new Integer[0];
+        Integer[] ints = new Integer[SIZE];
+        for (int i = 0; i < SIZE; ++i)
+            ints[i] = new Integer(SIZE - 1 - i);
+        TreeSet q = new TreeSet();
+        assertFalse(q.addAll(Arrays.asList(empty)));
+        assertTrue(q.addAll(Arrays.asList(ints)));
+        for (int i = 0; i < SIZE; ++i)
+            assertEquals(new Integer(i), q.pollFirst());
+    }
+
+    /**
+     * pollFirst succeeds unless empty
+     */
+    public void testPollFirst() {
+        TreeSet q = populatedSet(SIZE);
+        for (int i = 0; i < SIZE; ++i) {
+            assertEquals(i, q.pollFirst());
+        }
+        assertNull(q.pollFirst());
+    }
+
+    /**
+     * pollLast succeeds unless empty
+     */
+    public void testPollLast() {
+        TreeSet q = populatedSet(SIZE);
+        for (int i = SIZE - 1; i >= 0; --i) {
+            assertEquals(i, q.pollLast());
+        }
+        assertNull(q.pollFirst());
+    }
+
+    /**
+     * remove(x) removes x and returns true if present
+     */
+    public void testRemoveElement() {
+        TreeSet q = populatedSet(SIZE);
+        for (int i = 1; i < SIZE; i += 2) {
+            assertTrue(q.contains(i));
+            assertTrue(q.remove(i));
+            assertFalse(q.contains(i));
+            assertTrue(q.contains(i - 1));
+        }
+        for (int i = 0; i < SIZE; i += 2) {
+            assertTrue(q.contains(i));
+            assertTrue(q.remove(i));
+            assertFalse(q.contains(i));
+            assertFalse(q.remove(i + 1));
+            assertFalse(q.contains(i + 1));
+        }
+        assertTrue(q.isEmpty());
+    }
+
+    /**
+     * contains(x) reports true when elements added but not yet removed
+     */
+    public void testContains() {
+        TreeSet q = populatedSet(SIZE);
+        for (int i = 0; i < SIZE; ++i) {
+            assertTrue(q.contains(new Integer(i)));
+            q.pollFirst();
+            assertFalse(q.contains(new Integer(i)));
+        }
+    }
+
+    /**
+     * clear removes all elements
+     */
+    public void testClear() {
+        TreeSet q = populatedSet(SIZE);
+        q.clear();
+        assertTrue(q.isEmpty());
+        assertEquals(0, q.size());
+        q.add(new Integer(1));
+        assertFalse(q.isEmpty());
+        q.clear();
+        assertTrue(q.isEmpty());
+    }
+
+    /**
+     * containsAll(c) is true when c contains a subset of elements
+     */
+    public void testContainsAll() {
+        TreeSet q = populatedSet(SIZE);
+        TreeSet p = new TreeSet();
+        for (int i = 0; i < SIZE; ++i) {
+            assertTrue(q.containsAll(p));
+            assertFalse(p.containsAll(q));
+            p.add(new Integer(i));
+        }
+        assertTrue(p.containsAll(q));
+    }
+
+    /**
+     * retainAll(c) retains only those elements of c and reports true if changed
+     */
+    public void testRetainAll() {
+        TreeSet q = populatedSet(SIZE);
+        TreeSet p = populatedSet(SIZE);
+        for (int i = 0; i < SIZE; ++i) {
+            boolean changed = q.retainAll(p);
+            if (i == 0)
+                assertFalse(changed);
+            else
+                assertTrue(changed);
+
+            assertTrue(q.containsAll(p));
+            assertEquals(SIZE - i, q.size());
+            p.pollFirst();
+        }
+    }
+
+    /**
+     * removeAll(c) removes only those elements of c and reports true if changed
+     */
+    public void testRemoveAll() {
+        for (int i = 1; i < SIZE; ++i) {
+            TreeSet q = populatedSet(SIZE);
+            TreeSet p = populatedSet(i);
+            assertTrue(q.removeAll(p));
+            assertEquals(SIZE - i, q.size());
+            for (int j = 0; j < i; ++j) {
+                Integer x = (Integer)(p.pollFirst());
+                assertFalse(q.contains(x));
+            }
+        }
+    }
+
+    /**
+     * lower returns preceding element
+     */
+    public void testLower() {
+        TreeSet q = set5();
+        Object e1 = q.lower(three);
+        assertEquals(two, e1);
+
+        Object e2 = q.lower(six);
+        assertEquals(five, e2);
+
+        Object e3 = q.lower(one);
+        assertNull(e3);
+
+        Object e4 = q.lower(zero);
+        assertNull(e4);
+    }
+
+    /**
+     * higher returns next element
+     */
+    public void testHigher() {
+        TreeSet q = set5();
+        Object e1 = q.higher(three);
+        assertEquals(four, e1);
+
+        Object e2 = q.higher(zero);
+        assertEquals(one, e2);
+
+        Object e3 = q.higher(five);
+        assertNull(e3);
+
+        Object e4 = q.higher(six);
+        assertNull(e4);
+    }
+
+    /**
+     * floor returns preceding element
+     */
+    public void testFloor() {
+        TreeSet q = set5();
+        Object e1 = q.floor(three);
+        assertEquals(three, e1);
+
+        Object e2 = q.floor(six);
+        assertEquals(five, e2);
+
+        Object e3 = q.floor(one);
+        assertEquals(one, e3);
+
+        Object e4 = q.floor(zero);
+        assertNull(e4);
+    }
+
+    /**
+     * ceiling returns next element
+     */
+    public void testCeiling() {
+        TreeSet q = set5();
+        Object e1 = q.ceiling(three);
+        assertEquals(three, e1);
+
+        Object e2 = q.ceiling(zero);
+        assertEquals(one, e2);
+
+        Object e3 = q.ceiling(five);
+        assertEquals(five, e3);
+
+        Object e4 = q.ceiling(six);
+        assertNull(e4);
+    }
+
+    /**
+     * toArray contains all elements in sorted order
+     */
+    public void testToArray() {
+        TreeSet q = populatedSet(SIZE);
+        Object[] o = q.toArray();
+        for (int i = 0; i < o.length; i++)
+            assertSame(o[i], q.pollFirst());
+    }
+
+    /**
+     * toArray(a) contains all elements in sorted order
+     */
+    public void testToArray2() {
+        TreeSet<Integer> q = populatedSet(SIZE);
+        Integer[] ints = new Integer[SIZE];
+        Integer[] array = q.toArray(ints);
+        assertSame(ints, array);
+        for (int i = 0; i < ints.length; i++)
+            assertSame(ints[i], q.pollFirst());
+    }
+
+    /**
+     * iterator iterates through all elements
+     */
+    public void testIterator() {
+        TreeSet q = populatedSet(SIZE);
+        Iterator it = q.iterator();
+        int i;
+        for (i = 0; it.hasNext(); i++)
+            assertTrue(q.contains(it.next()));
+        assertEquals(i, SIZE);
+        assertIteratorExhausted(it);
+    }
+
+    /**
+     * iterator of empty set has no elements
+     */
+    public void testEmptyIterator() {
+        assertIteratorExhausted(new TreeSet().iterator());
+    }
+
+    /**
+     * iterator.remove removes current element
+     */
+    public void testIteratorRemove() {
+        final TreeSet q = new TreeSet();
+        q.add(new Integer(2));
+        q.add(new Integer(1));
+        q.add(new Integer(3));
+
+        Iterator it = q.iterator();
+        it.next();
+        it.remove();
+
+        it = q.iterator();
+        assertEquals(it.next(), new Integer(2));
+        assertEquals(it.next(), new Integer(3));
+        assertFalse(it.hasNext());
+    }
+
+    /**
+     * toString contains toStrings of elements
+     */
+    public void testToString() {
+        TreeSet q = populatedSet(SIZE);
+        String s = q.toString();
+        for (int i = 0; i < SIZE; ++i) {
+            assertTrue(s.contains(String.valueOf(i)));
+        }
+    }
+
+    /**
+     * A deserialized serialized set has same elements
+     */
+    public void testSerialization() throws Exception {
+        NavigableSet x = populatedSet(SIZE);
+        NavigableSet y = serialClone(x);
+
+        assertNotSame(x, y);
+        assertEquals(x.size(), y.size());
+        assertEquals(x, y);
+        assertEquals(y, x);
+        while (!x.isEmpty()) {
+            assertFalse(y.isEmpty());
+            assertEquals(x.pollFirst(), y.pollFirst());
+        }
+        assertTrue(y.isEmpty());
+    }
+
+    /**
+     * subSet returns set with keys in requested range
+     */
+    public void testSubSetContents() {
+        TreeSet set = set5();
+        SortedSet sm = set.subSet(two, four);
+        assertEquals(two, sm.first());
+        assertEquals(three, sm.last());
+        assertEquals(2, sm.size());
+        assertFalse(sm.contains(one));
+        assertTrue(sm.contains(two));
+        assertTrue(sm.contains(three));
+        assertFalse(sm.contains(four));
+        assertFalse(sm.contains(five));
+        Iterator i = sm.iterator();
+        Object k;
+        k = (Integer)(i.next());
+        assertEquals(two, k);
+        k = (Integer)(i.next());
+        assertEquals(three, k);
+        assertFalse(i.hasNext());
+        Iterator j = sm.iterator();
+        j.next();
+        j.remove();
+        assertFalse(set.contains(two));
+        assertEquals(4, set.size());
+        assertEquals(1, sm.size());
+        assertEquals(three, sm.first());
+        assertEquals(three, sm.last());
+        assertTrue(sm.remove(three));
+        assertTrue(sm.isEmpty());
+        assertEquals(3, set.size());
+    }
+
+    public void testSubSetContents2() {
+        TreeSet set = set5();
+        SortedSet sm = set.subSet(two, three);
+        assertEquals(1, sm.size());
+        assertEquals(two, sm.first());
+        assertEquals(two, sm.last());
+        assertFalse(sm.contains(one));
+        assertTrue(sm.contains(two));
+        assertFalse(sm.contains(three));
+        assertFalse(sm.contains(four));
+        assertFalse(sm.contains(five));
+        Iterator i = sm.iterator();
+        Object k;
+        k = (Integer)(i.next());
+        assertEquals(two, k);
+        assertFalse(i.hasNext());
+        Iterator j = sm.iterator();
+        j.next();
+        j.remove();
+        assertFalse(set.contains(two));
+        assertEquals(4, set.size());
+        assertEquals(0, sm.size());
+        assertTrue(sm.isEmpty());
+        assertFalse(sm.remove(three));
+        assertEquals(4, set.size());
+    }
+
+    /**
+     * headSet returns set with keys in requested range
+     */
+    public void testHeadSetContents() {
+        TreeSet set = set5();
+        SortedSet sm = set.headSet(four);
+        assertTrue(sm.contains(one));
+        assertTrue(sm.contains(two));
+        assertTrue(sm.contains(three));
+        assertFalse(sm.contains(four));
+        assertFalse(sm.contains(five));
+        Iterator i = sm.iterator();
+        Object k;
+        k = (Integer)(i.next());
+        assertEquals(one, k);
+        k = (Integer)(i.next());
+        assertEquals(two, k);
+        k = (Integer)(i.next());
+        assertEquals(three, k);
+        assertFalse(i.hasNext());
+        sm.clear();
+        assertTrue(sm.isEmpty());
+        assertEquals(2, set.size());
+        assertEquals(four, set.first());
+    }
+
+    /**
+     * tailSet returns set with keys in requested range
+     */
+    public void testTailSetContents() {
+        TreeSet set = set5();
+        SortedSet sm = set.tailSet(two);
+        assertFalse(sm.contains(one));
+        assertTrue(sm.contains(two));
+        assertTrue(sm.contains(three));
+        assertTrue(sm.contains(four));
+        assertTrue(sm.contains(five));
+        Iterator i = sm.iterator();
+        Object k;
+        k = (Integer)(i.next());
+        assertEquals(two, k);
+        k = (Integer)(i.next());
+        assertEquals(three, k);
+        k = (Integer)(i.next());
+        assertEquals(four, k);
+        k = (Integer)(i.next());
+        assertEquals(five, k);
+        assertFalse(i.hasNext());
+
+        SortedSet ssm = sm.tailSet(four);
+        assertEquals(four, ssm.first());
+        assertEquals(five, ssm.last());
+        assertTrue(ssm.remove(four));
+        assertEquals(1, ssm.size());
+        assertEquals(3, sm.size());
+        assertEquals(4, set.size());
+    }
+
+    Random rnd = new Random(666);
+    BitSet bs;
+
+    /**
+     * Subsets of subsets subdivide correctly
+     */
+    public void testRecursiveSubSets() throws Exception {
+        int setSize = expensiveTests ? 1000 : 100;
+        Class cl = TreeSet.class;
+
+        NavigableSet<Integer> set = newSet(cl);
+        bs = new BitSet(setSize);
+
+        populate(set, setSize);
+        check(set,                 0, setSize - 1, true);
+        check(set.descendingSet(), 0, setSize - 1, false);
+
+        mutateSet(set, 0, setSize - 1);
+        check(set,                 0, setSize - 1, true);
+        check(set.descendingSet(), 0, setSize - 1, false);
+
+        bashSubSet(set.subSet(0, true, setSize, false),
+                   0, setSize - 1, true);
+    }
+
+    /**
+     * addAll is idempotent
+     */
+    public void testAddAll_idempotent() throws Exception {
+        Set x = populatedSet(SIZE);
+        Set y = new TreeSet(x);
+        y.addAll(x);
+        assertEquals(x, y);
+        assertEquals(y, x);
+    }
+
+    static NavigableSet<Integer> newSet(Class cl) throws Exception {
+        NavigableSet<Integer> result = (NavigableSet<Integer>) cl.newInstance();
+        assertEquals(0, result.size());
+        assertFalse(result.iterator().hasNext());
+        return result;
+    }
+
+    void populate(NavigableSet<Integer> set, int limit) {
+        for (int i = 0, n = 2 * limit / 3; i < n; i++) {
+            int element = rnd.nextInt(limit);
+            put(set, element);
+        }
+    }
+
+    void mutateSet(NavigableSet<Integer> set, int min, int max) {
+        int size = set.size();
+        int rangeSize = max - min + 1;
+
+        // Remove a bunch of entries directly
+        for (int i = 0, n = rangeSize / 2; i < n; i++) {
+            remove(set, min - 5 + rnd.nextInt(rangeSize + 10));
+        }
+
+        // Remove a bunch of entries with iterator
+        for (Iterator<Integer> it = set.iterator(); it.hasNext(); ) {
+            if (rnd.nextBoolean()) {
+                bs.clear(it.next());
+                it.remove();
+            }
+        }
+
+        // Add entries till we're back to original size
+        while (set.size() < size) {
+            int element = min + rnd.nextInt(rangeSize);
+            assertTrue(element >= min && element <= max);
+            put(set, element);
+        }
+    }
+
+    void mutateSubSet(NavigableSet<Integer> set, int min, int max) {
+        int size = set.size();
+        int rangeSize = max - min + 1;
+
+        // Remove a bunch of entries directly
+        for (int i = 0, n = rangeSize / 2; i < n; i++) {
+            remove(set, min - 5 + rnd.nextInt(rangeSize + 10));
+        }
+
+        // Remove a bunch of entries with iterator
+        for (Iterator<Integer> it = set.iterator(); it.hasNext(); ) {
+            if (rnd.nextBoolean()) {
+                bs.clear(it.next());
+                it.remove();
+            }
+        }
+
+        // Add entries till we're back to original size
+        while (set.size() < size) {
+            int element = min - 5 + rnd.nextInt(rangeSize + 10);
+            if (element >= min && element <= max) {
+                put(set, element);
+            } else {
+                try {
+                    set.add(element);
+                    shouldThrow();
+                } catch (IllegalArgumentException success) {}
+            }
+        }
+    }
+
+    void put(NavigableSet<Integer> set, int element) {
+        if (set.add(element))
+            bs.set(element);
+    }
+
+    void remove(NavigableSet<Integer> set, int element) {
+        if (set.remove(element))
+            bs.clear(element);
+    }
+
+    void bashSubSet(NavigableSet<Integer> set,
+                    int min, int max, boolean ascending) {
+        check(set, min, max, ascending);
+        check(set.descendingSet(), min, max, !ascending);
+
+        mutateSubSet(set, min, max);
+        check(set, min, max, ascending);
+        check(set.descendingSet(), min, max, !ascending);
+
+        // Recurse
+        if (max - min < 2)
+            return;
+        int midPoint = (min + max) / 2;
+
+        // headSet - pick direction and endpoint inclusion randomly
+        boolean incl = rnd.nextBoolean();
+        NavigableSet<Integer> hm = set.headSet(midPoint, incl);
+        if (ascending) {
+            if (rnd.nextBoolean())
+                bashSubSet(hm, min, midPoint - (incl ? 0 : 1), true);
+            else
+                bashSubSet(hm.descendingSet(), min, midPoint - (incl ? 0 : 1),
+                           false);
+        } else {
+            if (rnd.nextBoolean())
+                bashSubSet(hm, midPoint + (incl ? 0 : 1), max, false);
+            else
+                bashSubSet(hm.descendingSet(), midPoint + (incl ? 0 : 1), max,
+                           true);
+        }
+
+        // tailSet - pick direction and endpoint inclusion randomly
+        incl = rnd.nextBoolean();
+        NavigableSet<Integer> tm = set.tailSet(midPoint,incl);
+        if (ascending) {
+            if (rnd.nextBoolean())
+                bashSubSet(tm, midPoint + (incl ? 0 : 1), max, true);
+            else
+                bashSubSet(tm.descendingSet(), midPoint + (incl ? 0 : 1), max,
+                           false);
+        } else {
+            if (rnd.nextBoolean()) {
+                bashSubSet(tm, min, midPoint - (incl ? 0 : 1), false);
+            } else {
+                bashSubSet(tm.descendingSet(), min, midPoint - (incl ? 0 : 1),
+                           true);
+            }
+        }
+
+        // subSet - pick direction and endpoint inclusion randomly
+        int rangeSize = max - min + 1;
+        int[] endpoints = new int[2];
+        endpoints[0] = min + rnd.nextInt(rangeSize);
+        endpoints[1] = min + rnd.nextInt(rangeSize);
+        Arrays.sort(endpoints);
+        boolean lowIncl = rnd.nextBoolean();
+        boolean highIncl = rnd.nextBoolean();
+        if (ascending) {
+            NavigableSet<Integer> sm = set.subSet(
+                endpoints[0], lowIncl, endpoints[1], highIncl);
+            if (rnd.nextBoolean())
+                bashSubSet(sm, endpoints[0] + (lowIncl ? 0 : 1),
+                           endpoints[1] - (highIncl ? 0 : 1), true);
+            else
+                bashSubSet(sm.descendingSet(), endpoints[0] + (lowIncl ? 0 : 1),
+                           endpoints[1] - (highIncl ? 0 : 1), false);
+        } else {
+            NavigableSet<Integer> sm = set.subSet(
+                endpoints[1], highIncl, endpoints[0], lowIncl);
+            if (rnd.nextBoolean())
+                bashSubSet(sm, endpoints[0] + (lowIncl ? 0 : 1),
+                           endpoints[1] - (highIncl ? 0 : 1), false);
+            else
+                bashSubSet(sm.descendingSet(), endpoints[0] + (lowIncl ? 0 : 1),
+                           endpoints[1] - (highIncl ? 0 : 1), true);
+        }
+    }
+
+    /**
+     * min and max are both inclusive.  If max < min, interval is empty.
+     */
+    void check(NavigableSet<Integer> set,
+                      final int min, final int max, final boolean ascending) {
+        class ReferenceSet {
+            int lower(int element) {
+                return ascending ?
+                    lowerAscending(element) : higherAscending(element);
+            }
+            int floor(int element) {
+                return ascending ?
+                    floorAscending(element) : ceilingAscending(element);
+            }
+            int ceiling(int element) {
+                return ascending ?
+                    ceilingAscending(element) : floorAscending(element);
+            }
+            int higher(int element) {
+                return ascending ?
+                    higherAscending(element) : lowerAscending(element);
+            }
+            int first() {
+                return ascending ? firstAscending() : lastAscending();
+            }
+            int last() {
+                return ascending ? lastAscending() : firstAscending();
+            }
+            int lowerAscending(int element) {
+                return floorAscending(element - 1);
+            }
+            int floorAscending(int element) {
+                if (element < min)
+                    return -1;
+                else if (element > max)
+                    element = max;
+
+                // BitSet should support this! Test would run much faster
+                while (element >= min) {
+                    if (bs.get(element))
+                        return element;
+                    element--;
+                }
+                return -1;
+            }
+            int ceilingAscending(int element) {
+                if (element < min)
+                    element = min;
+                else if (element > max)
+                    return -1;
+                int result = bs.nextSetBit(element);
+                return (result > max) ? -1 : result;
+            }
+            int higherAscending(int element) {
+                return ceilingAscending(element + 1);
+            }
+            private int firstAscending() {
+                int result = ceilingAscending(min);
+                return (result > max) ? -1 : result;
+            }
+            private int lastAscending() {
+                int result = floorAscending(max);
+                return (result < min) ? -1 : result;
+            }
+        }
+        ReferenceSet rs = new ReferenceSet();
+
+        // Test contents using containsElement
+        int size = 0;
+        for (int i = min; i <= max; i++) {
+            boolean bsContainsI = bs.get(i);
+            assertEquals(bsContainsI, set.contains(i));
+            if (bsContainsI)
+                size++;
+        }
+        assertEquals(size, set.size());
+
+        // Test contents using contains elementSet iterator
+        int size2 = 0;
+        int previousElement = -1;
+        for (int element : set) {
+            assertTrue(bs.get(element));
+            size2++;
+            assertTrue(previousElement < 0 || (ascending ?
+                element - previousElement > 0 : element - previousElement < 0));
+            previousElement = element;
+        }
+        assertEquals(size2, size);
+
+        // Test navigation ops
+        for (int element = min - 1; element <= max + 1; element++) {
+            assertEq(set.lower(element), rs.lower(element));
+            assertEq(set.floor(element), rs.floor(element));
+            assertEq(set.higher(element), rs.higher(element));
+            assertEq(set.ceiling(element), rs.ceiling(element));
+        }
+
+        // Test extrema
+        if (set.size() != 0) {
+            assertEq(set.first(), rs.first());
+            assertEq(set.last(), rs.last());
+        } else {
+            assertEq(rs.first(), -1);
+            assertEq(rs.last(),  -1);
+            try {
+                set.first();
+                shouldThrow();
+            } catch (NoSuchElementException success) {}
+            try {
+                set.last();
+                shouldThrow();
+            } catch (NoSuchElementException success) {}
+        }
+    }
+
+    static void assertEq(Integer i, int j) {
+        if (i == null)
+            assertEquals(j, -1);
+        else
+            assertEquals((int) i, j);
+    }
+
+    static boolean eq(Integer i, int j) {
+        return (i == null) ? j == -1 : i == j;
+    }
+
+}