@Override
        public void write(char[] cbuf, int off, int len) throws IOException {
            written.append(String.copyValueOf(cbuf, off, len));
        }
Completeness check for GenericWriter.

@author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
vespajlib/src/test/java/com/yahoo/text/GenericWriterTestCase.java