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, Integer.toString(MediaTypeEnum.XML.getCode()));
        WebResponse response = runner.getResponse(request);
        // we are really testing an xml output?
        assertEquals("Expected a different content type.", "text/xml", response.getContentType());
        assertEquals("Wrong or missing disposition/filename.", "attachment; filename=\"file.txt\"", response
            .getHeaderField("CONTENT-DISPOSITION"));
}

Test for content disposition and filename.

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