public void getInstance() throws Exception {
ServletRunner servletRunner = new ServletRunner();
servletRunner.registerServlet("/app1/*", HttpServlet.class.getName());
ServletUnitClient client = servletRunner.newClient();
request = client.newInvocation("http://localhost/app1").getRequest();
assertNull(request.getAttribute("_webx_errorHandlerHelper_"));
helper = ErrorHandlerHelper.getInstance(request);
assertSame(helper, ErrorHandlerHelper.getInstance(request));
assertSame(helper, request.getAttribute("_webx_errorHandlerHelper_"));