ListFactories.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * published by the Free Software Foundation.
 *
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.stream.Stream;

import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

import static java.util.Arrays.asList;

import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertFalse;
import static org.testng.Assert.assertNotEquals;
import static org.testng.Assert.assertNotSame;
import static org.testng.Assert.assertSame;
import static org.testng.Assert.assertTrue;
import static org.testng.Assert.fail;

/*
 * @test
 * @bug 8048330 8203184
 * @summary Test convenience static factory methods on List.
 * @run testng ListFactories
 */

public class ListFactories {

    static final int NUM_STRINGS = 20; // should be larger than the largest fixed-arg overload
    static final String[] stringArray;
    static {
        String[] sa = new String[NUM_STRINGS];
        for (int i = 0; i < NUM_STRINGS; i++) {
            sa[i] = String.valueOf((char)('a' + i));
        }
        stringArray = sa;
    }

    // returns array of [actual, expected]
    static Object[] a(List<String> act, List<String> exp) {
        return new Object[] { act, exp };
    }

    @DataProvider(name="empty")
    public Iterator<Object[]> empty() {
        return Collections.singletonList(
            a(List.of(), asList())
        ).iterator();
    }

    @DataProvider(name="nonempty")
    public Iterator<Object[]> nonempty() {
        return asList(
            a(List.of("a"),
               asList("a")),
            a(List.of("a", "b"),
               asList("a", "b")),
            a(List.of("a", "b", "c"),
               asList("a", "b", "c")),
            a(List.of("a", "b", "c", "d"),
               asList("a", "b", "c", "d")),
            a(List.of("a", "b", "c", "d", "e"),
               asList("a", "b", "c", "d", "e")),
            a(List.of("a", "b", "c", "d", "e", "f"),
               asList("a", "b", "c", "d", "e", "f")),
            a(List.of("a", "b", "c", "d", "e", "f", "g"),
               asList("a", "b", "c", "d", "e", "f", "g")),
            a(List.of("a", "b", "c", "d", "e", "f", "g", "h"),
               asList("a", "b", "c", "d", "e", "f", "g", "h")),
            a(List.of("a", "b", "c", "d", "e", "f", "g", "h", "i"),
               asList("a", "b", "c", "d", "e", "f", "g", "h", "i")),
            a(List.of("a", "b", "c", "d", "e", "f", "g", "h", "i", "j"),
               asList("a", "b", "c", "d", "e", "f", "g", "h", "i", "j")),
            a(List.of(stringArray),
               asList(stringArray))
        ).iterator();
    }

    @DataProvider(name="sublists")
    public Iterator<Object[]> sublists() {
        return asList(
            a(List.<String>of().subList(0,0),
               asList()),
            a(List.of("a").subList(0,0),
               asList("a").subList(0,0)),
            a(List.of("a", "b").subList(0,1),
               asList("a", "b").subList(0,1)),
            a(List.of("a", "b", "c").subList(1,3),
               asList("a", "b", "c").subList(1,3)),
            a(List.of("a", "b", "c", "d").subList(0,4),
               asList("a", "b", "c", "d").subList(0,4)),
            a(List.of("a", "b", "c", "d", "e").subList(0,3),
               asList("a", "b", "c", "d", "e").subList(0,3)),
            a(List.of("a", "b", "c", "d", "e", "f").subList(3, 5),
               asList("a", "b", "c", "d", "e", "f").subList(3, 5)),
            a(List.of("a", "b", "c", "d", "e", "f", "g").subList(0, 7),
               asList("a", "b", "c", "d", "e", "f", "g").subList(0, 7)),
            a(List.of("a", "b", "c", "d", "e", "f", "g", "h").subList(0, 0),
               asList("a", "b", "c", "d", "e", "f", "g", "h").subList(0, 0)),
            a(List.of("a", "b", "c", "d", "e", "f", "g", "h", "i").subList(4, 5),
               asList("a", "b", "c", "d", "e", "f", "g", "h", "i").subList(4, 5)),
            a(List.of("a", "b", "c", "d", "e", "f", "g", "h", "i", "j").subList(1,10),
               asList("a", "b", "c", "d", "e", "f", "g", "h", "i", "j").subList(1,10)),
            a(List.of(stringArray).subList(5, NUM_STRINGS),
               asList(Arrays.copyOfRange(stringArray, 5, NUM_STRINGS)))
                ).iterator();
    }

    @DataProvider(name="all")
    public Iterator<Object[]> all() {
        List<Object[]> all = new ArrayList<>();
        empty().forEachRemaining(all::add);
        nonempty().forEachRemaining(all::add);
        sublists().forEachRemaining(all::add);
        return all.iterator();
    }

    @DataProvider(name="nonsublists")
    public Iterator<Object[]> nonsublists() {
        List<Object[]> all = new ArrayList<>();
        empty().forEachRemaining(all::add);
        nonempty().forEachRemaining(all::add);
        return all.iterator();
    }

    @Test(dataProvider="all", expectedExceptions=UnsupportedOperationException.class)
    public void cannotAddLast(List<String> act, List<String> exp) {
        act.add("x");
    }

    @Test(dataProvider="all", expectedExceptions=UnsupportedOperationException.class)
    public void cannotAddFirst(List<String> act, List<String> exp) {
        act.add(0, "x");
    }

    @Test(dataProvider="nonempty", expectedExceptions=UnsupportedOperationException.class)
    public void cannotRemove(List<String> act, List<String> exp) {
        act.remove(0);
    }

    @Test(dataProvider="nonempty", expectedExceptions=UnsupportedOperationException.class)
    public void cannotSet(List<String> act, List<String> exp) {
        act.set(0, "x");
    }

    @Test(dataProvider="all")
    public void contentsMatch(List<String> act, List<String> exp) {
        assertEquals(act, exp);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed1() {
        List.of((Object)null); // force one-arg overload
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed2a() {
        List.of("a", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed2b() {
        List.of(null, "b");
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed3() {
        List.of("a", "b", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed4() {
        List.of("a", "b", "c", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed5() {
        List.of("a", "b", "c", "d", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed6() {
        List.of("a", "b", "c", "d", "e", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed7() {
        List.of("a", "b", "c", "d", "e", "f", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed8() {
        List.of("a", "b", "c", "d", "e", "f", "g", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed9() {
        List.of("a", "b", "c", "d", "e", "f", "g", "h", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowed10() {
        List.of("a", "b", "c", "d", "e", "f", "g", "h", "i", null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullDisallowedN() {
        String[] array = stringArray.clone();
        array[0] = null;
        List.of(array);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void nullArrayDisallowed() {
        List.of((Object[])null);
    }

    @Test
    public void ensureArrayCannotModifyList() {
        String[] array = stringArray.clone();
        List<String> list = List.of(array);
        array[0] = "xyzzy";
        assertEquals(list, Arrays.asList(stringArray));
    }

    @Test(dataProvider="all", expectedExceptions=NullPointerException.class)
    public void containsNullShouldThrowNPE(List<String> act, List<String> exp) {
        act.contains(null);
    }

    @Test(dataProvider="all", expectedExceptions=NullPointerException.class)
    public void indexOfNullShouldThrowNPE(List<String> act, List<String> exp) {
        act.indexOf(null);
    }

    @Test(dataProvider="all", expectedExceptions=NullPointerException.class)
    public void lastIndexOfNullShouldThrowNPE(List<String> act, List<String> exp) {
        act.lastIndexOf(null);
    }

    // List.of().subList views should not be Serializable
    @Test(dataProvider="sublists")
    public void isNotSerializable(List<String> act, List<String> exp) {
        assertFalse(act instanceof Serializable);
    }

    // ... but List.of() should be
    @Test(dataProvider="nonsublists")
    public void serialEquality(List<String> act, List<String> exp) {
        // assume that act.equals(exp) tested elsewhere
        List<String> copy = serialClone(act);
        assertEquals(act, copy);
        assertEquals(copy, exp);
    }

    @SuppressWarnings("unchecked")
    static <T> T serialClone(T obj) {
        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            try (ObjectOutputStream oos = new ObjectOutputStream(baos)) {
                oos.writeObject(obj);
            }
            ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
            ObjectInputStream ois = new ObjectInputStream(bais);
            return (T) ois.readObject();
        } catch (IOException | ClassNotFoundException e) {
            throw new AssertionError(e);
        }
    }

    List<Integer> genList() {
        return new ArrayList<>(Arrays.asList(1, 2, 3));
    }

    @Test
    public void copyOfResultsEqual() {
        List<Integer> orig = genList();
        List<Integer> copy = List.copyOf(orig);

        assertEquals(orig, copy);
        assertEquals(copy, orig);
    }

    @Test
    public void copyOfModifiedUnequal() {
        List<Integer> orig = genList();
        List<Integer> copy = List.copyOf(orig);
        orig.add(4);

        assertNotEquals(orig, copy);
        assertNotEquals(copy, orig);
    }

    @Test
    public void copyOfIdentity() {
        List<Integer> orig = genList();
        List<Integer> copy1 = List.copyOf(orig);
        List<Integer> copy2 = List.copyOf(copy1);

        assertNotSame(orig, copy1);
        assertSame(copy1, copy2);
    }

    @Test
    public void copyOfSubList() {
        List<Integer> orig = List.of(0, 1, 2, 3);
        List<Integer> sub = orig.subList(0, 3);
        List<Integer> copy = List.copyOf(sub);

        assertNotSame(sub, copy);
    }

    @Test
    public void copyOfSubSubList() {
        List<Integer> orig = List.of(0, 1, 2, 3);
        List<Integer> sub = orig.subList(0, 3).subList(0, 2);
        List<Integer> copy = List.copyOf(sub);

        assertNotSame(sub, copy);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void copyOfRejectsNullCollection() {
        List<Integer> list = List.copyOf(null);
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void copyOfRejectsNullElements() {
        List<Integer> list = List.copyOf(Arrays.asList(1, null, 3));
    }

    @Test(expectedExceptions=NullPointerException.class)
    public void copyOfRejectsNullElements2() {
        List<String> list = List.copyOf(Stream.of("a", null, "c").toList());
    }

    @Test
    public void copyOfCopiesNullAllowingList() {
        List<String> orig = Stream.of("a", "b", "c").toList();
        List<String> copy = List.copyOf(orig);

        assertNotSame(orig, copy);
    }

    @Test
    public void iteratorShouldNotBeListIterator() {
        List<Integer> list = List.of(1, 2, 3, 4, 5);
        Iterator<Integer> it = list.iterator();
        it.next();
        try {
            ((ListIterator<Integer>) it).previous();
            fail("ListIterator operation succeeded on Iterator");
        } catch (ClassCastException|UnsupportedOperationException ignore) { }
    }
}