The Tor Browser / file revision

 /* Any copyright is dedicated to the Public Domain.

  * http://creativecommons.org/publicdomain/zero/1.0/ */

 function test() {

   waitForExplicitFinish();

   Task.spawn(function task() {

     let tab = gBrowser.selectedTab = gBrowser.addTab("about:mozilla");

     yield promiseBrowserLoaded(gBrowser.selectedBrowser);

     let win = gBrowser.replaceTabWithWindow(tab);

     yield promiseDelayedStartupFinished(win);

     yield promiseBrowserHasURL(win.gBrowser.browsers[0], "about:mozilla");

     win.duplicateTabIn(win.gBrowser.selectedTab, "tab");

     let browser = win.gBrowser.browsers[1];

     yield promiseBrowserLoaded(browser);

     is(browser.currentURI.spec, "about:mozilla", "tab was duplicated");

     win.close();

   }).then(finish);

 }

 function promiseDelayedStartupFinished(win) {

   let deferred = Promise.defer();

   whenDelayedStartupFinished(win, deferred.resolve);

   return deferred.promise;

 }

 function promiseBrowserHasURL(browser, url) {

   let promise = Promise.resolve();

   if (browser.contentDocument.readyState === "complete" &&

       browser.currentURI.spec === url) {

     return promise;

   }

   return promise.then(() => promiseBrowserHasURL(browser, url));

 }