test/tck/LinkedListTest.java

/*
 * 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/
 * Other contributors include Andrew Wright, Jeffrey Hayes,
 * Pat Fisher, Mike Judd.
 */

import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.concurrent.ThreadLocalRandom;

import junit.framework.Test;

public class LinkedListTest extends JSR166TestCase {
    public static void main(String[] args) {
        main(suite(), args);
    }

    public static Test suite() {
        class Implementation implements CollectionImplementation {
            public Class<?> klazz() { return LinkedList.class; }
            public List emptyCollection() { return new LinkedList(); }
            public Object makeElement(int i) { return i; }
            public boolean isConcurrent() { return false; }
            public boolean permitsNulls() { return true; }
        }
        class SubListImplementation extends Implementation {
            public List emptyCollection() {
                List list = super.emptyCollection();
                ThreadLocalRandom rnd = ThreadLocalRandom.current();
                if (rnd.nextBoolean())
                    list.add(makeElement(rnd.nextInt()));
                int i = rnd.nextInt(list.size() + 1);
                return list.subList(i, i);
            }
        }
        return newTestSuite(
                LinkedListTest.class,
                CollectionTest.testSuite(new Implementation()),
                CollectionTest.testSuite(new SubListImplementation()));
    }

    /**
     * Returns a new queue of given size containing consecutive
     * Integers 0 ... n - 1.
     */
    private static LinkedList<Integer> populatedQueue(int n) {
        LinkedList<Integer> q = new LinkedList<>();
        assertTrue(q.isEmpty());
        for (int i = 0; i < n; ++i)
            assertTrue(q.offer(new Integer(i)));
        assertFalse(q.isEmpty());
        assertEquals(n, q.size());
        assertEquals((Integer) 0, q.peekFirst());
        assertEquals((Integer) (n - 1), q.peekLast());
        return q;
    }

    /**
     * new queue is empty
     */
    public void testConstructor1() {
        assertEquals(0, new LinkedList().size());
    }

    /**
     * Initializing from null Collection throws NPE
     */
    public void testConstructor3() {
        try {
            new LinkedList((Collection)null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * Queue contains all elements of collection used to initialize
     */
    public void testConstructor6() {
        Integer[] ints = new Integer[SIZE];
        for (int i = 0; i < SIZE; ++i)
            ints[i] = i;
        LinkedList q = new LinkedList(Arrays.asList(ints));
        for (int i = 0; i < SIZE; ++i)
            assertEquals(ints[i], q.poll());
    }

    /**
     * isEmpty is true before add, false after
     */
    public void testEmpty() {
        LinkedList q = new LinkedList();
        assertTrue(q.isEmpty());
        q.add(new Integer(1));
        assertFalse(q.isEmpty());
        q.add(new Integer(2));
        q.remove();
        q.remove();
        assertTrue(q.isEmpty());
    }

    /**
     * size changes when elements added and removed
     */
    public void testSize() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(SIZE - i, q.size());
            q.remove();
        }
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.size());
            q.add(new Integer(i));
        }
    }

    /**
     * offer(null) succeeds
     */
    public void testOfferNull() {
        LinkedList q = new LinkedList();
        q.offer(null);
        assertNull(q.get(0));
        assertTrue(q.contains(null));
    }

    /**
     * Offer succeeds
     */
    public void testOffer() {
        LinkedList q = new LinkedList();
        assertTrue(q.offer(new Integer(0)));
        assertTrue(q.offer(new Integer(1)));
    }

    /**
     * add succeeds
     */
    public void testAdd() {
        LinkedList q = new LinkedList();
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.size());
            assertTrue(q.add(new Integer(i)));
        }
    }

    /**
     * addAll(null) throws NPE
     */
    public void testAddAll1() {
        LinkedList q = new LinkedList();
        try {
            q.addAll(null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * Queue contains all elements, in traversal order, of successful addAll
     */
    public void testAddAll5() {
        Integer[] empty = new Integer[0];
        Integer[] ints = new Integer[SIZE];
        for (int i = 0; i < SIZE; ++i)
            ints[i] = i;
        LinkedList q = new LinkedList();
        assertFalse(q.addAll(Arrays.asList(empty)));
        assertTrue(q.addAll(Arrays.asList(ints)));
        for (int i = 0; i < SIZE; ++i)
            assertEquals(ints[i], q.poll());
    }

    /**
     * addAll with too large an index throws IOOBE
     */
    public void testAddAll2_IndexOutOfBoundsException() {
        LinkedList l = new LinkedList();
        l.add(new Object());
        LinkedList m = new LinkedList();
        m.add(new Object());
        try {
            l.addAll(4,m);
            shouldThrow();
        } catch (IndexOutOfBoundsException success) {}
    }

    /**
     * addAll with negative index throws IOOBE
     */
    public void testAddAll4_BadIndex() {
        LinkedList l = new LinkedList();
        l.add(new Object());
        LinkedList m = new LinkedList();
        m.add(new Object());
        try {
            l.addAll(-1,m);
            shouldThrow();
        } catch (IndexOutOfBoundsException success) {}
    }

    /**
     * poll succeeds unless empty
     */
    public void testPoll() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.poll());
        }
        assertNull(q.poll());
    }

    /**
     * peek returns next element, or null if empty
     */
    public void testPeek() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.peek());
            assertEquals(i, q.poll());
            assertTrue(q.peek() == null ||
                       !q.peek().equals(i));
        }
        assertNull(q.peek());
    }

    /**
     * element returns next element, or throws NSEE if empty
     */
    public void testElement() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.element());
            assertEquals(i, q.poll());
        }
        try {
            q.element();
            shouldThrow();
        } catch (NoSuchElementException success) {}
    }

    /**
     * remove removes next element, or throws NSEE if empty
     */
    public void testRemove() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.remove());
        }
        try {
            q.remove();
            shouldThrow();
        } catch (NoSuchElementException success) {}
    }

    /**
     * remove(x) removes x and returns true if present
     */
    public void testRemoveElement() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 1; i < SIZE; i += 2) {
            assertTrue(q.contains(i));
            assertTrue(q.remove((Integer)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((Integer)i));
            assertFalse(q.contains(i));
            assertFalse(q.remove((Integer)(i + 1)));
            assertFalse(q.contains(i + 1));
        }
        assertTrue(q.isEmpty());
    }

    /**
     * contains(x) reports true when elements added but not yet removed
     */
    public void testContains() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(q.contains(new Integer(i)));
            q.poll();
            assertFalse(q.contains(new Integer(i)));
        }
    }

    /**
     * clear removes all elements
     */
    public void testClear() {
        LinkedList q = populatedQueue(SIZE);
        q.clear();
        assertTrue(q.isEmpty());
        assertEquals(0, q.size());
        assertTrue(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() {
        LinkedList q = populatedQueue(SIZE);
        LinkedList p = new LinkedList();
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(q.containsAll(p));
            assertFalse(p.containsAll(q));
            assertTrue(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() {
        LinkedList q = populatedQueue(SIZE);
        LinkedList p = populatedQueue(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.remove();
        }
    }

    /**
     * removeAll(c) removes only those elements of c and reports true if changed
     */
    public void testRemoveAll() {
        for (int i = 1; i < SIZE; ++i) {
            LinkedList q = populatedQueue(SIZE);
            LinkedList p = populatedQueue(i);
            assertTrue(q.removeAll(p));
            assertEquals(SIZE - i, q.size());
            for (int j = 0; j < i; ++j) {
                Integer x = (Integer)(p.remove());
                assertFalse(q.contains(x));
            }
        }
    }

    /**
     * toArray contains all elements in FIFO order
     */
    public void testToArray() {
        LinkedList q = populatedQueue(SIZE);
        Object[] a = q.toArray();
        assertSame(Object[].class, a.getClass());
        for (Object o : a)
            assertSame(o, q.poll());
        assertTrue(q.isEmpty());
    }

    /**
     * toArray(a) contains all elements in FIFO order
     */
    public void testToArray2() {
        LinkedList<Integer> q = populatedQueue(SIZE);
        Integer[] ints = new Integer[SIZE];
        Integer[] array = q.toArray(ints);
        assertSame(ints, array);
        for (Integer o : ints)
            assertSame(o, q.poll());
        assertTrue(q.isEmpty());
    }

    /**
     * toArray(null) throws NullPointerException
     */
    public void testToArray_NullArg() {
        LinkedList l = new LinkedList();
        l.add(new Object());
        try {
            l.toArray((Object[])null);
            shouldThrow();
        } catch (NullPointerException success) {}
    }

    /**
     * toArray(incompatible array type) throws ArrayStoreException
     */
    public void testToArray1_BadArg() {
        LinkedList l = new LinkedList();
        l.add(new Integer(5));
        try {
            l.toArray(new String[10]);
            shouldThrow();
        } catch (ArrayStoreException success) {}
    }

    /**
     * iterator iterates through all elements
     */
    public void testIterator() {
        LinkedList q = populatedQueue(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 collection has no elements
     */
    public void testEmptyIterator() {
        assertIteratorExhausted(new LinkedList().iterator());
    }

    /**
     * iterator ordering is FIFO
     */
    public void testIteratorOrdering() {
        final LinkedList q = new LinkedList();
        q.add(new Integer(1));
        q.add(new Integer(2));
        q.add(new Integer(3));
        int k = 0;
        for (Iterator it = q.iterator(); it.hasNext();) {
            assertEquals(++k, it.next());
        }

        assertEquals(3, k);
    }

    /**
     * iterator.remove removes current element
     */
    public void testIteratorRemove() {
        final LinkedList q = new LinkedList();
        q.add(new Integer(1));
        q.add(new Integer(2));
        q.add(new Integer(3));
        Iterator it = q.iterator();
        assertEquals(1, it.next());
        it.remove();
        it = q.iterator();
        assertEquals(2, it.next());
        assertEquals(3, it.next());
        assertFalse(it.hasNext());
    }

    /**
     * Descending iterator iterates through all elements
     */
    public void testDescendingIterator() {
        LinkedList q = populatedQueue(SIZE);
        int i = 0;
        Iterator it = q.descendingIterator();
        while (it.hasNext()) {
            assertTrue(q.contains(it.next()));
            ++i;
        }
        assertEquals(i, SIZE);
        assertFalse(it.hasNext());
        try {
            it.next();
            shouldThrow();
        } catch (NoSuchElementException success) {}
    }

    /**
     * Descending iterator ordering is reverse FIFO
     */
    public void testDescendingIteratorOrdering() {
        final LinkedList q = new LinkedList();
        q.add(new Integer(3));
        q.add(new Integer(2));
        q.add(new Integer(1));
        int k = 0;
        for (Iterator it = q.descendingIterator(); it.hasNext();) {
            assertEquals(++k, it.next());
        }

        assertEquals(3, k);
    }

    /**
     * descendingIterator.remove removes current element
     */
    public void testDescendingIteratorRemove() {
        final LinkedList q = new LinkedList();
        q.add(three);
        q.add(two);
        q.add(one);
        Iterator it = q.descendingIterator();
        it.next();
        it.remove();
        it = q.descendingIterator();
        assertSame(it.next(), two);
        assertSame(it.next(), three);
        assertFalse(it.hasNext());
    }

    /**
     * toString contains toStrings of elements
     */
    public void testToString() {
        LinkedList q = populatedQueue(SIZE);
        String s = q.toString();
        for (int i = 0; i < SIZE; ++i) {
            assertTrue(s.contains(String.valueOf(i)));
        }
    }

    /**
     * peek returns element inserted with addFirst
     */
    public void testAddFirst() {
        LinkedList q = populatedQueue(3);
        q.addFirst(four);
        assertSame(four, q.peek());
    }

    /**
     * peekFirst returns element inserted with push
     */
    public void testPush() {
        LinkedList q = populatedQueue(3);
        q.push(four);
        assertSame(four, q.peekFirst());
    }

    /**
     * pop removes next element, or throws NSEE if empty
     */
    public void testPop() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.pop());
        }
        try {
            q.pop();
            shouldThrow();
        } catch (NoSuchElementException success) {}
    }

    /**
     * OfferFirst succeeds
     */
    public void testOfferFirst() {
        LinkedList q = new LinkedList();
        assertTrue(q.offerFirst(new Integer(0)));
        assertTrue(q.offerFirst(new Integer(1)));
    }

    /**
     * OfferLast succeeds
     */
    public void testOfferLast() {
        LinkedList q = new LinkedList();
        assertTrue(q.offerLast(new Integer(0)));
        assertTrue(q.offerLast(new Integer(1)));
    }

    /**
     * pollLast succeeds unless empty
     */
    public void testPollLast() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = SIZE - 1; i >= 0; --i) {
            assertEquals(i, q.pollLast());
        }
        assertNull(q.pollLast());
    }

    /**
     * peekFirst returns next element, or null if empty
     */
    public void testPeekFirst() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.peekFirst());
            assertEquals(i, q.pollFirst());
            assertTrue(q.peekFirst() == null ||
                       !q.peekFirst().equals(i));
        }
        assertNull(q.peekFirst());
    }

    /**
     * peekLast returns next element, or null if empty
     */
    public void testPeekLast() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = SIZE - 1; i >= 0; --i) {
            assertEquals(i, q.peekLast());
            assertEquals(i, q.pollLast());
            assertTrue(q.peekLast() == null ||
                       !q.peekLast().equals(i));
        }
        assertNull(q.peekLast());
    }

    public void testFirstElement() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 0; i < SIZE; ++i) {
            assertEquals(i, q.getFirst());
            assertEquals(i, q.pollFirst());
        }
        try {
            q.getFirst();
            shouldThrow();
        } catch (NoSuchElementException success) {}
    }

    /**
     * getLast returns next element, or throws NSEE if empty
     */
    public void testLastElement() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = SIZE - 1; i >= 0; --i) {
            assertEquals(i, q.getLast());
            assertEquals(i, q.pollLast());
        }
        try {
            q.getLast();
            shouldThrow();
        } catch (NoSuchElementException success) {}
        assertNull(q.peekLast());
    }

    /**
     * removeFirstOccurrence(x) removes x and returns true if present
     */
    public void testRemoveFirstOccurrence() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 1; i < SIZE; i += 2) {
            assertTrue(q.removeFirstOccurrence(new Integer(i)));
        }
        for (int i = 0; i < SIZE; i += 2) {
            assertTrue(q.removeFirstOccurrence(new Integer(i)));
            assertFalse(q.removeFirstOccurrence(new Integer(i + 1)));
        }
        assertTrue(q.isEmpty());
    }

    /**
     * removeLastOccurrence(x) removes x and returns true if present
     */
    public void testRemoveLastOccurrence() {
        LinkedList q = populatedQueue(SIZE);
        for (int i = 1; i < SIZE; i += 2) {
            assertTrue(q.removeLastOccurrence(new Integer(i)));
        }
        for (int i = 0; i < SIZE; i += 2) {
            assertTrue(q.removeLastOccurrence(new Integer(i)));
            assertFalse(q.removeLastOccurrence(new Integer(i + 1)));
        }
        assertTrue(q.isEmpty());
    }

}
Revision:	1.49
Committed:	Fri Jun 22 00:04:58 2018 UTC (5 years, 11 months ago) by jsr166
Branch:	MAIN
Changes since 1.48:	+1 -1 lines
Log Message:	sync upstream changes
#	Content
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	* Other contributors include Andrew Wright, Jeffrey Hayes,
6	* Pat Fisher, Mike Judd.
7	*/
8
9	import java.util.Arrays;
10	import java.util.Collection;
11	import java.util.Iterator;
12	import java.util.LinkedList;
13	import java.util.List;
14	import java.util.NoSuchElementException;
15	import java.util.concurrent.ThreadLocalRandom;
16
17	import junit.framework.Test;
18
19	public class LinkedListTest extends JSR166TestCase {
20	public static void main(String[] args) {
21	main(suite(), args);
22	}
23
24	public static Test suite() {
25	class Implementation implements CollectionImplementation {
26	public Class<?> klazz() { return LinkedList.class; }
27	public List emptyCollection() { return new LinkedList(); }
28	public Object makeElement(int i) { return i; }
29	public boolean isConcurrent() { return false; }
30	public boolean permitsNulls() { return true; }
31	}
32	class SubListImplementation extends Implementation {
33	public List emptyCollection() {
34	List list = super.emptyCollection();
35	ThreadLocalRandom rnd = ThreadLocalRandom.current();
36	if (rnd.nextBoolean())
37	list.add(makeElement(rnd.nextInt()));
38	int i = rnd.nextInt(list.size() + 1);
39	return list.subList(i, i);
40	}
41	}
42	return newTestSuite(
43	LinkedListTest.class,
44	CollectionTest.testSuite(new Implementation()),
45	CollectionTest.testSuite(new SubListImplementation()));
46	}
47
48	/**
49	* Returns a new queue of given size containing consecutive
50	* Integers 0 ... n - 1.
51	*/
52	private static LinkedList<Integer> populatedQueue(int n) {
53	LinkedList<Integer> q = new LinkedList<>();
54	assertTrue(q.isEmpty());
55	for (int i = 0; i < n; ++i)
56	assertTrue(q.offer(new Integer(i)));
57	assertFalse(q.isEmpty());
58	assertEquals(n, q.size());
59	assertEquals((Integer) 0, q.peekFirst());
60	assertEquals((Integer) (n - 1), q.peekLast());
61	return q;
62	}
63
64	/**
65	* new queue is empty
66	*/
67	public void testConstructor1() {
68	assertEquals(0, new LinkedList().size());
69	}
70
71	/**
72	* Initializing from null Collection throws NPE
73	*/
74	public void testConstructor3() {
75	try {
76	new LinkedList((Collection)null);
77	shouldThrow();
78	} catch (NullPointerException success) {}
79	}
80
81	/**
82	* Queue contains all elements of collection used to initialize
83	*/
84	public void testConstructor6() {
85	Integer[] ints = new Integer[SIZE];
86	for (int i = 0; i < SIZE; ++i)
87	ints[i] = i;
88	LinkedList q = new LinkedList(Arrays.asList(ints));
89	for (int i = 0; i < SIZE; ++i)
90	assertEquals(ints[i], q.poll());
91	}
92
93	/**
94	* isEmpty is true before add, false after
95	*/
96	public void testEmpty() {
97	LinkedList q = new LinkedList();
98	assertTrue(q.isEmpty());
99	q.add(new Integer(1));
100	assertFalse(q.isEmpty());
101	q.add(new Integer(2));
102	q.remove();
103	q.remove();
104	assertTrue(q.isEmpty());
105	}
106
107	/**
108	* size changes when elements added and removed
109	*/
110	public void testSize() {
111	LinkedList q = populatedQueue(SIZE);
112	for (int i = 0; i < SIZE; ++i) {
113	assertEquals(SIZE - i, q.size());
114	q.remove();
115	}
116	for (int i = 0; i < SIZE; ++i) {
117	assertEquals(i, q.size());
118	q.add(new Integer(i));
119	}
120	}
121
122	/**
123	* offer(null) succeeds
124	*/
125	public void testOfferNull() {
126	LinkedList q = new LinkedList();
127	q.offer(null);
128	assertNull(q.get(0));
129	assertTrue(q.contains(null));
130	}
131
132	/**
133	* Offer succeeds
134	*/
135	public void testOffer() {
136	LinkedList q = new LinkedList();
137	assertTrue(q.offer(new Integer(0)));
138	assertTrue(q.offer(new Integer(1)));
139	}
140
141	/**
142	* add succeeds
143	*/
144	public void testAdd() {
145	LinkedList q = new LinkedList();
146	for (int i = 0; i < SIZE; ++i) {
147	assertEquals(i, q.size());
148	assertTrue(q.add(new Integer(i)));
149	}
150	}
151
152	/**
153	* addAll(null) throws NPE
154	*/
155	public void testAddAll1() {
156	LinkedList q = new LinkedList();
157	try {
158	q.addAll(null);
159	shouldThrow();
160	} catch (NullPointerException success) {}
161	}
162
163	/**
164	* Queue contains all elements, in traversal order, of successful addAll
165	*/
166	public void testAddAll5() {
167	Integer[] empty = new Integer[0];
168	Integer[] ints = new Integer[SIZE];
169	for (int i = 0; i < SIZE; ++i)
170	ints[i] = i;
171	LinkedList q = new LinkedList();
172	assertFalse(q.addAll(Arrays.asList(empty)));
173	assertTrue(q.addAll(Arrays.asList(ints)));
174	for (int i = 0; i < SIZE; ++i)
175	assertEquals(ints[i], q.poll());
176	}
177
178	/**
179	* addAll with too large an index throws IOOBE
180	*/
181	public void testAddAll2_IndexOutOfBoundsException() {
182	LinkedList l = new LinkedList();
183	l.add(new Object());
184	LinkedList m = new LinkedList();
185	m.add(new Object());
186	try {
187	l.addAll(4,m);
188	shouldThrow();
189	} catch (IndexOutOfBoundsException success) {}
190	}
191
192	/**
193	* addAll with negative index throws IOOBE
194	*/
195	public void testAddAll4_BadIndex() {
196	LinkedList l = new LinkedList();
197	l.add(new Object());
198	LinkedList m = new LinkedList();
199	m.add(new Object());
200	try {
201	l.addAll(-1,m);
202	shouldThrow();
203	} catch (IndexOutOfBoundsException success) {}
204	}
205
206	/**
207	* poll succeeds unless empty
208	*/
209	public void testPoll() {
210	LinkedList q = populatedQueue(SIZE);
211	for (int i = 0; i < SIZE; ++i) {
212	assertEquals(i, q.poll());
213	}
214	assertNull(q.poll());
215	}
216
217	/**
218	* peek returns next element, or null if empty
219	*/
220	public void testPeek() {
221	LinkedList q = populatedQueue(SIZE);
222	for (int i = 0; i < SIZE; ++i) {
223	assertEquals(i, q.peek());
224	assertEquals(i, q.poll());
225	assertTrue(q.peek() == null \|\|
226	!q.peek().equals(i));
227	}
228	assertNull(q.peek());
229	}
230
231	/**
232	* element returns next element, or throws NSEE if empty
233	*/
234	public void testElement() {
235	LinkedList q = populatedQueue(SIZE);
236	for (int i = 0; i < SIZE; ++i) {
237	assertEquals(i, q.element());
238	assertEquals(i, q.poll());
239	}
240	try {
241	q.element();
242	shouldThrow();
243	} catch (NoSuchElementException success) {}
244	}
245
246	/**
247	* remove removes next element, or throws NSEE if empty
248	*/
249	public void testRemove() {
250	LinkedList q = populatedQueue(SIZE);
251	for (int i = 0; i < SIZE; ++i) {
252	assertEquals(i, q.remove());
253	}
254	try {
255	q.remove();
256	shouldThrow();
257	} catch (NoSuchElementException success) {}
258	}
259
260	/**
261	* remove(x) removes x and returns true if present
262	*/
263	public void testRemoveElement() {
264	LinkedList q = populatedQueue(SIZE);
265	for (int i = 1; i < SIZE; i += 2) {
266	assertTrue(q.contains(i));
267	assertTrue(q.remove((Integer)i));
268	assertFalse(q.contains(i));
269	assertTrue(q.contains(i - 1));
270	}
271	for (int i = 0; i < SIZE; i += 2) {
272	assertTrue(q.contains(i));
273	assertTrue(q.remove((Integer)i));
274	assertFalse(q.contains(i));
275	assertFalse(q.remove((Integer)(i + 1)));
276	assertFalse(q.contains(i + 1));
277	}
278	assertTrue(q.isEmpty());
279	}
280
281	/**
282	* contains(x) reports true when elements added but not yet removed
283	*/
284	public void testContains() {
285	LinkedList q = populatedQueue(SIZE);
286	for (int i = 0; i < SIZE; ++i) {
287	assertTrue(q.contains(new Integer(i)));
288	q.poll();
289	assertFalse(q.contains(new Integer(i)));
290	}
291	}
292
293	/**
294	* clear removes all elements
295	*/
296	public void testClear() {
297	LinkedList q = populatedQueue(SIZE);
298	q.clear();
299	assertTrue(q.isEmpty());
300	assertEquals(0, q.size());
301	assertTrue(q.add(new Integer(1)));
302	assertFalse(q.isEmpty());
303	q.clear();
304	assertTrue(q.isEmpty());
305	}
306
307	/**
308	* containsAll(c) is true when c contains a subset of elements
309	*/
310	public void testContainsAll() {
311	LinkedList q = populatedQueue(SIZE);
312	LinkedList p = new LinkedList();
313	for (int i = 0; i < SIZE; ++i) {
314	assertTrue(q.containsAll(p));
315	assertFalse(p.containsAll(q));
316	assertTrue(p.add(new Integer(i)));
317	}
318	assertTrue(p.containsAll(q));
319	}
320
321	/**
322	* retainAll(c) retains only those elements of c and reports true if changed
323	*/
324	public void testRetainAll() {
325	LinkedList q = populatedQueue(SIZE);
326	LinkedList p = populatedQueue(SIZE);
327	for (int i = 0; i < SIZE; ++i) {
328	boolean changed = q.retainAll(p);
329	if (i == 0)
330	assertFalse(changed);
331	else
332	assertTrue(changed);
333
334	assertTrue(q.containsAll(p));
335	assertEquals(SIZE - i, q.size());
336	p.remove();
337	}
338	}
339
340	/**
341	* removeAll(c) removes only those elements of c and reports true if changed
342	*/
343	public void testRemoveAll() {
344	for (int i = 1; i < SIZE; ++i) {
345	LinkedList q = populatedQueue(SIZE);
346	LinkedList p = populatedQueue(i);
347	assertTrue(q.removeAll(p));
348	assertEquals(SIZE - i, q.size());
349	for (int j = 0; j < i; ++j) {
350	Integer x = (Integer)(p.remove());
351	assertFalse(q.contains(x));
352	}
353	}
354	}
355
356	/**
357	* toArray contains all elements in FIFO order
358	*/
359	public void testToArray() {
360	LinkedList q = populatedQueue(SIZE);
361	Object[] a = q.toArray();
362	assertSame(Object[].class, a.getClass());
363	for (Object o : a)
364	assertSame(o, q.poll());
365	assertTrue(q.isEmpty());
366	}
367
368	/**
369	* toArray(a) contains all elements in FIFO order
370	*/
371	public void testToArray2() {
372	LinkedList<Integer> q = populatedQueue(SIZE);
373	Integer[] ints = new Integer[SIZE];
374	Integer[] array = q.toArray(ints);
375	assertSame(ints, array);
376	for (Integer o : ints)
377	assertSame(o, q.poll());
378	assertTrue(q.isEmpty());
379	}
380
381	/**
382	* toArray(null) throws NullPointerException
383	*/
384	public void testToArray_NullArg() {
385	LinkedList l = new LinkedList();
386	l.add(new Object());
387	try {
388	l.toArray((Object[])null);
389	shouldThrow();
390	} catch (NullPointerException success) {}
391	}
392
393	/**
394	* toArray(incompatible array type) throws ArrayStoreException
395	*/
396	public void testToArray1_BadArg() {
397	LinkedList l = new LinkedList();
398	l.add(new Integer(5));
399	try {
400	l.toArray(new String[10]);
401	shouldThrow();
402	} catch (ArrayStoreException success) {}
403	}
404
405	/**
406	* iterator iterates through all elements
407	*/
408	public void testIterator() {
409	LinkedList q = populatedQueue(SIZE);
410	Iterator it = q.iterator();
411	int i;
412	for (i = 0; it.hasNext(); i++)
413	assertTrue(q.contains(it.next()));
414	assertEquals(i, SIZE);
415	assertIteratorExhausted(it);
416	}
417
418	/**
419	* iterator of empty collection has no elements
420	*/
421	public void testEmptyIterator() {
422	assertIteratorExhausted(new LinkedList().iterator());
423	}
424
425	/**
426	* iterator ordering is FIFO
427	*/
428	public void testIteratorOrdering() {
429	final LinkedList q = new LinkedList();
430	q.add(new Integer(1));
431	q.add(new Integer(2));
432	q.add(new Integer(3));
433	int k = 0;
434	for (Iterator it = q.iterator(); it.hasNext();) {
435	assertEquals(++k, it.next());
436	}
437
438	assertEquals(3, k);
439	}
440
441	/**
442	* iterator.remove removes current element
443	*/
444	public void testIteratorRemove() {
445	final LinkedList q = new LinkedList();
446	q.add(new Integer(1));
447	q.add(new Integer(2));
448	q.add(new Integer(3));
449	Iterator it = q.iterator();
450	assertEquals(1, it.next());
451	it.remove();
452	it = q.iterator();
453	assertEquals(2, it.next());
454	assertEquals(3, it.next());
455	assertFalse(it.hasNext());
456	}
457
458	/**
459	* Descending iterator iterates through all elements
460	*/
461	public void testDescendingIterator() {
462	LinkedList q = populatedQueue(SIZE);
463	int i = 0;
464	Iterator it = q.descendingIterator();
465	while (it.hasNext()) {
466	assertTrue(q.contains(it.next()));
467	++i;
468	}
469	assertEquals(i, SIZE);
470	assertFalse(it.hasNext());
471	try {
472	it.next();
473	shouldThrow();
474	} catch (NoSuchElementException success) {}
475	}
476
477	/**
478	* Descending iterator ordering is reverse FIFO
479	*/
480	public void testDescendingIteratorOrdering() {
481	final LinkedList q = new LinkedList();
482	q.add(new Integer(3));
483	q.add(new Integer(2));
484	q.add(new Integer(1));
485	int k = 0;
486	for (Iterator it = q.descendingIterator(); it.hasNext();) {
487	assertEquals(++k, it.next());
488	}
489
490	assertEquals(3, k);
491	}
492
493	/**
494	* descendingIterator.remove removes current element
495	*/
496	public void testDescendingIteratorRemove() {
497	final LinkedList q = new LinkedList();
498	q.add(three);
499	q.add(two);
500	q.add(one);
501	Iterator it = q.descendingIterator();
502	it.next();
503	it.remove();
504	it = q.descendingIterator();
505	assertSame(it.next(), two);
506	assertSame(it.next(), three);
507	assertFalse(it.hasNext());
508	}
509
510	/**
511	* toString contains toStrings of elements
512	*/
513	public void testToString() {
514	LinkedList q = populatedQueue(SIZE);
515	String s = q.toString();
516	for (int i = 0; i < SIZE; ++i) {
517	assertTrue(s.contains(String.valueOf(i)));
518	}
519	}
520
521	/**
522	* peek returns element inserted with addFirst
523	*/
524	public void testAddFirst() {
525	LinkedList q = populatedQueue(3);
526	q.addFirst(four);
527	assertSame(four, q.peek());
528	}
529
530	/**
531	* peekFirst returns element inserted with push
532	*/
533	public void testPush() {
534	LinkedList q = populatedQueue(3);
535	q.push(four);
536	assertSame(four, q.peekFirst());
537	}
538
539	/**
540	* pop removes next element, or throws NSEE if empty
541	*/
542	public void testPop() {
543	LinkedList q = populatedQueue(SIZE);
544	for (int i = 0; i < SIZE; ++i) {
545	assertEquals(i, q.pop());
546	}
547	try {
548	q.pop();
549	shouldThrow();
550	} catch (NoSuchElementException success) {}
551	}
552
553	/**
554	* OfferFirst succeeds
555	*/
556	public void testOfferFirst() {
557	LinkedList q = new LinkedList();
558	assertTrue(q.offerFirst(new Integer(0)));
559	assertTrue(q.offerFirst(new Integer(1)));
560	}
561
562	/**
563	* OfferLast succeeds
564	*/
565	public void testOfferLast() {
566	LinkedList q = new LinkedList();
567	assertTrue(q.offerLast(new Integer(0)));
568	assertTrue(q.offerLast(new Integer(1)));
569	}
570
571	/**
572	* pollLast succeeds unless empty
573	*/
574	public void testPollLast() {
575	LinkedList q = populatedQueue(SIZE);
576	for (int i = SIZE - 1; i >= 0; --i) {
577	assertEquals(i, q.pollLast());
578	}
579	assertNull(q.pollLast());
580	}
581
582	/**
583	* peekFirst returns next element, or null if empty
584	*/
585	public void testPeekFirst() {
586	LinkedList q = populatedQueue(SIZE);
587	for (int i = 0; i < SIZE; ++i) {
588	assertEquals(i, q.peekFirst());
589	assertEquals(i, q.pollFirst());
590	assertTrue(q.peekFirst() == null \|\|
591	!q.peekFirst().equals(i));
592	}
593	assertNull(q.peekFirst());
594	}
595
596	/**
597	* peekLast returns next element, or null if empty
598	*/
599	public void testPeekLast() {
600	LinkedList q = populatedQueue(SIZE);
601	for (int i = SIZE - 1; i >= 0; --i) {
602	assertEquals(i, q.peekLast());
603	assertEquals(i, q.pollLast());
604	assertTrue(q.peekLast() == null \|\|
605	!q.peekLast().equals(i));
606	}
607	assertNull(q.peekLast());
608	}
609
610	public void testFirstElement() {
611	LinkedList q = populatedQueue(SIZE);
612	for (int i = 0; i < SIZE; ++i) {
613	assertEquals(i, q.getFirst());
614	assertEquals(i, q.pollFirst());
615	}
616	try {
617	q.getFirst();
618	shouldThrow();
619	} catch (NoSuchElementException success) {}
620	}
621
622	/**
623	* getLast returns next element, or throws NSEE if empty
624	*/
625	public void testLastElement() {
626	LinkedList q = populatedQueue(SIZE);
627	for (int i = SIZE - 1; i >= 0; --i) {
628	assertEquals(i, q.getLast());
629	assertEquals(i, q.pollLast());
630	}
631	try {
632	q.getLast();
633	shouldThrow();
634	} catch (NoSuchElementException success) {}
635	assertNull(q.peekLast());
636	}
637
638	/**
639	* removeFirstOccurrence(x) removes x and returns true if present
640	*/
641	public void testRemoveFirstOccurrence() {
642	LinkedList q = populatedQueue(SIZE);
643	for (int i = 1; i < SIZE; i += 2) {
644	assertTrue(q.removeFirstOccurrence(new Integer(i)));
645	}
646	for (int i = 0; i < SIZE; i += 2) {
647	assertTrue(q.removeFirstOccurrence(new Integer(i)));
648	assertFalse(q.removeFirstOccurrence(new Integer(i + 1)));
649	}
650	assertTrue(q.isEmpty());
651	}
652
653	/**
654	* removeLastOccurrence(x) removes x and returns true if present
655	*/
656	public void testRemoveLastOccurrence() {
657	LinkedList q = populatedQueue(SIZE);
658	for (int i = 1; i < SIZE; i += 2) {
659	assertTrue(q.removeLastOccurrence(new Integer(i)));
660	}
661	for (int i = 0; i < SIZE; i += 2) {
662	assertTrue(q.removeLastOccurrence(new Integer(i)));
663	assertFalse(q.removeLastOccurrence(new Integer(i + 1)));
664	}
665	assertTrue(q.isEmpty());
666	}
667
668	}