The Tor Browser / file revision

 const Cu = Components.utils;

 const { Services } = Cu.import("resource://gre/modules/Services.jsm");

 // Load a duplicated copy of the jsm to prevent messing with the currently running one

 let scope = {};

 Services.scriptloader.loadSubScript("resource://gre/modules/SystemAppProxy.jsm", scope);

 const { SystemAppProxy } = scope;

 let frame;

 let index = -1;

 function next() {

   index++;

   if (index >= steps.length) {

     assert.ok(false, "Shouldn't get here!");

     return;

   }

   try {

     steps[index]();

   } catch(ex) {

     assert.ok(false, "Caught exception: " + ex);

   }

 }

 // Listen for events received by the system app document

 // to ensure that we receive all of them, in an expected order and time

 let isLoaded = false;

 let n = 0;

 function listener(event) {

   if (!isLoaded) {

     assert.ok(false, "Received event before the iframe is ready");

     return;

   }

   n++;

   if (n == 1) {

     assert.equal(event.type, "mozChromeEvent");

     assert.equal(event.detail.name, "first");

   } else if (n == 2) {

     assert.equal(event.type, "custom");

     assert.equal(event.detail.name, "second");

     next(); // call checkEventDispatching

   } else if (n == 3) {

     assert.equal(event.type, "custom");

     assert.equal(event.detail.name, "third");

   } else if (n == 4) {

     assert.equal(event.type, "mozChromeEvent");

     assert.equal(event.detail.name, "fourth");

     next(); // call checkEventListening();

   } else {

     assert.ok(false, "Unexpected event of type " + event.type);

   }

 }

 let steps = [

   function waitForWebapps() {

     // We are using webapps API later in this test and we need to ensure

     // it is fully initialized before trying to use it

     let { DOMApplicationRegistry } =  Cu.import('resource://gre/modules/Webapps.jsm', {});

     DOMApplicationRegistry.registryReady.then(function () {

       next();

     });

   },

   function earlyEvents() {

     // Immediately try to send events

     SystemAppProxy.dispatchEvent({ name: "first" });

     SystemAppProxy._sendCustomEvent("custom", { name: "second" });

     next();

   },

   function createFrame() {

     // Create a fake system app frame

     let win = Services.wm.getMostRecentWindow("navigator:browser");

     let doc = win.document;

     frame = doc.createElement("iframe");

     doc.documentElement.appendChild(frame);

     // Ensure that events are correctly sent to the frame.

     // `listener` is going to call next()

     frame.contentWindow.addEventListener("mozChromeEvent", listener);

     frame.contentWindow.addEventListener("custom", listener);

     // Ensure that listener being registered before the system app is ready

     // are correctly removed from the pending list

     function removedListener() {

       assert(false, "Listener isn't correctly removed from the pending list");

     }

     SystemAppProxy.addEventListener("mozChromeEvent", removedListener);

     SystemAppProxy.removeEventListener("mozChromeEvent", removedListener);

     // Register it to the JSM

     SystemAppProxy.registerFrame(frame);

     assert.ok(true, "Frame created and registered");

     frame.contentWindow.addEventListener("load", function onload() {

       frame.contentWindow.removeEventListener("load", onload);

       assert.ok(true, "Frame document loaded");

       // Declare that the iframe is now loaded.

       // That should dispatch early events

       isLoaded = true;

       SystemAppProxy.setIsReady();

       assert.ok(true, "Frame declared as loaded");

       // Once pending events are received,

       // we will run checkEventDispatching from `listener` function

     });

     frame.setAttribute("src", "data:text/html,system app");

   },

   function checkEventDispatching() {

     // Send events after the iframe is ready,

     // they should be dispatched right away

     SystemAppProxy._sendCustomEvent("custom", { name: "third" });

     SystemAppProxy.dispatchEvent({ name: "fourth" });

     // Once this 4th event is received, we will run checkEventListening

   },

   function checkEventListening() {

     SystemAppProxy.addEventListener("mozContentEvent", function onContentEvent(event) {

       assert.equal(event.detail.name, "first-content", "received a system app event");

       SystemAppProxy.removeEventListener("mozContentEvent", onContentEvent);

       next();

     });

     let win = frame.contentWindow;

     win.dispatchEvent(new win.CustomEvent("mozContentEvent", { detail: {name: "first-content"} }));

   },

   function endOfTest() {

     frame.remove();

     sendAsyncMessage("finish");

   }

 ];

 next();