Cu.import("resource://testing-common/httpd.js"); Cu.import("resource://gre/modules/NetUtil.jsm"); const SERVER_PORT = 8080; const baseURL = "http://localhost:" + SERVER_PORT + "/"; var cookie = ""; for (let i =0; i < 10000; i++) { cookie += " big cookie"; } var listener = { onStartRequest: function (request, ctx) { }, onDataAvailable: function (request, ctx, stream) { }, onStopRequest: function (request, ctx, status) { do_check_eq(status, Components.results.NS_OK); do_test_finished(); }, }; function run_test() { var server = new HttpServer(); server.start(SERVER_PORT); server.registerPathHandler('/', function(metadata, response) { response.setStatusLine(metadata.httpVersion, 200, "OK"); response.setHeader("Set-Cookie", "BigCookie=" + cookie, false); response.write("Hello world"); }); var chan = NetUtil.newChannel({uri: baseURL, loadUsingSystemPrincipal: true}) .QueryInterface(Components.interfaces.nsIHttpChannel); chan.asyncOpen2(listener); do_test_pending(); }