@Override
    public String toString(Charset charset) {
        return toString(readerIndex, readableBytes(), charset);
    }
@Test
    public void testToString() {
        ByteBuf copied = copiedBuffer("Hello, World!", CharsetUtil.ISO_8859_1);
        buffer.clear();
        buffer.writeBytes(copied);
        assertEquals("Hello, World!", buffer.toString(CharsetUtil.ISO_8859_1));
        copied.release();
    }