/**
* Simulate uploading a file so that it will trick a form handler to think a file upload failed
* @param string $varname the form name expected
* @param string $filename the file name expected
* @param string $mimetype the mime type the file is expcted to be
*/
function UploadInvalidFile($varname, $filename, $mimetype = "text/plain")
{
// set request to testmode so we can fake an upload
RequestUtil::$TestMode = true;
$_FILES[$varname] = $this->GetUploadStructure($varname, $filename, $mimetype, 4);
}