jdk-24/test/jdk/java/util/StringJoiner/MergeTest.java

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/**
 * @test
 * @bug 8017231 8020977 8054221
 * @summary test  StringJoiner::merge
 * @modules java.base/jdk.internal.util
 * @requires vm.bits == "64" & os.maxMemory > 4G
 * @run testng/othervm -Xmx4g -XX:+CompactStrings MergeTest
 */

import java.util.StringJoiner;
import java.util.stream.Stream;
import org.testng.annotations.Test;
import static jdk.internal.util.ArraysSupport.SOFT_MAX_ARRAY_LENGTH;
import static org.testng.Assert.assertEquals;
import static org.testng.Assert.fail;

@Test
public class MergeTest {
    private static final String[] PREFIXES = {"", "{", "@#$%"};
    private static final String[] SUFFIXES = {"", "}", "*&%$"};

    private static class Fixes {
        public String pre0, suf0;
        public String pre1, suf1;
        public Fixes(String prefix0, String suffix0,
                     String prefix1, String suffix1) {
            this.pre0 = prefix0;
            this.suf0 = suffix0;
            this.pre1 = prefix1;
            this.suf1 = suffix1;
        }
    }

    private static Stream<Fixes> fixesStream() {
        Stream.Builder<Fixes> builder = Stream.builder();
        for (final String prefix0 : PREFIXES) {
            for (final String suffix0 : SUFFIXES) {
                for (final String prefix1 : PREFIXES) {
                    for (final String suffix1 : SUFFIXES) {
                        builder.accept(new Fixes(prefix0, suffix0,
                                                 prefix1, suffix1));
                    }
                }
            }
        }
        return builder.build();
    }

    @Test(expectedExceptions = {NullPointerException.class})
    public void testNull() {
        StringJoiner sj = new StringJoiner(",", "{", "}");
        sj.merge(null);
    }

    public void testSimple() {
        fixesStream().forEach(fixes -> {
            StringJoiner sj = new StringJoiner(",", fixes.pre0, fixes.suf0);
            StringJoiner other = new StringJoiner(",", fixes.pre1, fixes.suf1);
            Stream.of("a", "b", "c").forEachOrdered(sj::add);
            Stream.of("d", "e", "f").forEachOrdered(other::add);

            sj.merge(other);
            assertEquals(sj.toString(), fixes.pre0 + "a,b,c,d,e,f" + fixes.suf0);
        });
    }

    public void testEmptyOther() {
        fixesStream().forEach(fixes -> {
            StringJoiner sj = new StringJoiner(",", fixes.pre0, fixes.suf0);
            StringJoiner other = new StringJoiner(",", fixes.pre1, fixes.suf1);
            Stream.of("a", "b", "c").forEachOrdered(sj::add);

            sj.merge(other);
            assertEquals(sj.toString(), fixes.pre0 + "a,b,c" + fixes.suf0);

            other.setEmptyValue("EMPTY");
            sj.merge(other);
            assertEquals(sj.toString(), fixes.pre0 + "a,b,c" + fixes.suf0);
        });
    }

    public void testEmptyThis() {
        fixesStream().forEach(fixes -> {
            StringJoiner sj = new StringJoiner(",", fixes.pre0, fixes.suf0);
            StringJoiner other = new StringJoiner(":", fixes.pre1, fixes.suf1);
            Stream.of("d", "e", "f").forEachOrdered(other::add);

            sj.merge(other);
            assertEquals(sj.toString(), fixes.pre0 + "d:e:f" + fixes.suf0);

            sj = new StringJoiner(",", fixes.pre0, fixes.suf0).setEmptyValue("EMPTY");
            assertEquals(sj.toString(), "EMPTY");
            sj.merge(other);
            assertEquals(sj.toString(), fixes.pre0 + "d:e:f" + fixes.suf0);
        });
    }

    public void testEmptyBoth() {
        fixesStream().forEach(fixes -> {
            StringJoiner sj = new StringJoiner(",", fixes.pre0, fixes.suf0);
            StringJoiner other = new StringJoiner(":", fixes.pre1, fixes.suf1);

            sj.merge(other);
            assertEquals(sj.toString(), fixes.pre0 + fixes.suf0);

            other.setEmptyValue("NOTHING");
            sj.merge(other);
            assertEquals(sj.toString(), fixes.pre0 + fixes.suf0);

            sj = new StringJoiner(",", fixes.pre0, fixes.suf0).setEmptyValue("EMPTY");
            assertEquals(sj.toString(), "EMPTY");
            sj.merge(other);
            assertEquals(sj.toString(), "EMPTY");
        });
    }

    public void testCascadeEmpty() {
        fixesStream().forEach(fixes -> {
            StringJoiner sj = new StringJoiner(",", fixes.pre0, fixes.suf0);
            StringJoiner o1 = new StringJoiner(":", fixes.pre1, fixes.suf1).setEmptyValue("Empty1");
            StringJoiner o2 = new StringJoiner(",", "<", ">").setEmptyValue("Empty2");

            o1.merge(o2);
            assertEquals(o1.toString(), "Empty1");

            sj.merge(o1);
            assertEquals(sj.toString(), fixes.pre0 + fixes.suf0);
        });
    }

    public void testDelimiter() {
        fixesStream().forEach(fixes -> {
            StringJoiner sj = new StringJoiner(",", fixes.pre0, fixes.suf0);
            StringJoiner other = new StringJoiner(":", fixes.pre1, fixes.suf1);
            Stream.of("a", "b", "c").forEachOrdered(sj::add);
            Stream.of("d", "e", "f").forEachOrdered(other::add);

            sj.merge(other);
            assertEquals(sj.toString(), fixes.pre0 + "a,b,c,d:e:f" + fixes.suf0);
        });
    }

    public void testMergeSelf() {
        fixesStream().forEach(fixes -> {
            final StringJoiner sj = new StringJoiner(",", fixes.pre0, fixes.suf0).add("a").add("b");
            assertEquals(sj.merge(sj).toString(), fixes.pre0 + "a,b,a,b" + fixes.suf0);
            assertEquals(sj.merge(sj).toString(), fixes.pre0 + "a,b,a,b,a,b,a,b" + fixes.suf0);
        });
    }

    public void OOM() {
        String maxString = "*".repeat(SOFT_MAX_ARRAY_LENGTH);

        try {
            StringJoiner sj1 = new StringJoiner("", "", "");
            sj1.add(maxString);
            StringJoiner sj2 = new StringJoiner("", "", "");
            sj2.add(maxString);
            sj1.merge(sj2);
            fail("Should have thrown OutOfMemoryError");
        } catch (OutOfMemoryError ex) {
            // okay
        }
    }
}