test/jdk/java/lang/CharSequence/GetChars.java

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import org.testng.Assert;
import org.testng.annotations.Test;

/**
 * @test
 * @bug 8343110
 * @summary Check for expected behavior of default implementation of
 *          CharSequence.getChars().
 * @run testng GetChars
 */
public class GetChars {
    private static CharSequence CS = new CharSequence() {
        @Override
        public int length() {
            return 4;
        }

        @Override
        public char charAt(int index) {
            return "Test".charAt(index);
        }

        @Override
        public CharSequence subSequence(int start, int end) {
            throw new UnsupportedOperationException();
        }
    };

    @Test
    public void testExactCopy() {
        var dst = new char[4];
        CS.getChars(0, 4, dst, 0);
        Assert.assertEquals(dst, new char[] {'T', 'e', 's', 't'});
    }

    @Test
    public void testPartialCopy() {
        var dst = new char[2];
        CS.getChars(1, 3, dst, 0);
        Assert.assertEquals(dst, new char[] {'e', 's'});
    }

    @Test
    public void testPositionedCopy() {
        var dst = new char[] {1, 2, 3, 4, 5, 6};
        CS.getChars(0, 4, dst, 1);
        Assert.assertEquals(dst, new char[] {1, 'T', 'e', 's', 't', 6});
    }

    @Test
    public void testSrcBeginIsNegative() {
        Assert.assertThrows(IndexOutOfBoundsException.class,
                () -> CS.getChars(-1, 3, new char[4], 0));
    }

    @Test
    public void testDstBeginIsNegative() {
        Assert.assertThrows(IndexOutOfBoundsException.class,
                () -> CS.getChars(0, 4, new char[4], -1));
    }

    @Test
    public void testSrcBeginIsGreaterThanSrcEnd() {
        Assert.assertThrows(IndexOutOfBoundsException.class,
                () -> CS.getChars(4, 0, new char[4], 0));
    }

    @Test
    public void testSrcEndIsGreaterThanSequenceLength() {
        Assert.assertThrows(IndexOutOfBoundsException.class,
                () -> CS.getChars(0, 5, new char[4], 0));
    }

    @Test
    public void testRequestedLengthIsGreaterThanDstLength() {
        Assert.assertThrows(IndexOutOfBoundsException.class,
                () -> CS.getChars(0, 4, new char[3], 0));
    }

    @Test
    public void testDstIsNull() {
        Assert.assertThrows(NullPointerException.class,
                () -> CS.getChars(0, 4, null, 0));
    }

}