public  void doTest(String jspName) throws Exception 
{
        ParamEncoder encoder = new ParamEncoder("table");
        String mediaParameter = encoder.encodeParameterName(TableTagParameters.PARAMETER_EXPORTTYPE);
        WebRequest request = new GetMethodWebRequest(jspName);
        request.setParameter(mediaParameter, "" + MediaTypeEnum.XML.getCode());
        WebResponse response = runner.getResponse(request);
        if (log.isDebugEnabled())
        {
            log.debug(response.getText());
        }
        assertEquals("Expected a different content type.", "text/xml", response.getContentType());
        assertFalse("Export should not be decorated", StringUtils.contains(
            response.getText(),
            (String) new DateColumnDecorator().decorate(KnownTypes.TIME_VALUE, null, null)));
        assertTrue("Export should not be decorated", StringUtils.contains(response.getText(), KnownTypes.TIME_VALUE
            .toString()));
}

Export should not be decorated.

 public String getJspName() 
{
        return "columndecorator.jsp";
}