expose unique tab ids to the high-level tabs module

lib/sdk/tabs/tab-fennec.js

@@ -8,7 +8,7 @@ const { Class } = require('../core/heritage');
 const { tabNS } = require('./namespace');
 const { EventTarget } = require('../event/target');
 const { activateTab, getTabTitle, setTabTitle, closeTab, getTabURL,
-        setTabURL, getOwnerWindow, getTabContentType } = require('./utils');
+        setTabURL, getOwnerWindow, getTabContentType, getTabId } = require('./utils');
 const { emit } = require('../event/core');
 const { when: unload } = require('../system/unload');
 
@@ -63,6 +63,10 @@ const Tab = Class({
     return 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAFAAAAAtCAYAAAA5reyyAAAAJElEQVRoge3BAQEAAACCIP+vbkhAAQAAAAAAAAAAAAAAAADXBjhtAAGQ0AF/AAAAAElFTkSuQmCC';
   },
 
+  get id() {
+    return getTabId(tabNS(this).tab);
+  },
+
   /**
    * The index of the tab relative to other tabs in the application window.
    * Changing this property will change order of the actual position of the tab.

lib/sdk/tabs/tab-firefox.js

@@ -10,7 +10,7 @@ const { EVENTS } = require("./events");
 const { getThumbnailURIForWindow } = require("../content/thumbnail");
 const { getFaviconURIForLocation } = require("../io/data");
 const { activateTab, getOwnerWindow, getBrowserForTab, getTabTitle, setTabTitle,
-        getTabURL, setTabURL, getTabContentType } = require('./utils');
+        getTabURL, setTabURL, getTabContentType, getTabId } = require('./utils');
 
 // Array of the inner instances of all the wrapped tabs.
 const TABS = [];
@@ -94,6 +94,11 @@ const TabTrait = Trait.compose(EventEmitter, {
    */
   get _contentWindow() this._browser.contentWindow,
 
+  /**
+   * Unique id for the tab, actually maps to tab.linkedPanel but with some munging.
+   */
+  get id() getTabId(this._tab),
+
   /**
    * The title of the page currently loaded in the tab.
    * Changing this property changes an actual title.

lib/sdk/tabs/utils.js

@@ -150,6 +150,15 @@ function getBrowserForTab(tab) {
 }
 exports.getBrowserForTab = getBrowserForTab;
 
+function getTabId(tab) {
+  if (tab.browser) // fennec
+    return tab.id
+
+  return String.split(tab.linkedPanel, 'panel').pop();
+}
+exports.getTabId = getTabId;
+
+
 function getTabTitle(tab) {
   return getBrowserForTab(tab).contentDocument.title || tab.label || "";
 }

test/tabs/test-fennec-tabs.js

@@ -125,6 +125,7 @@ exports.testTabProperties = function(test) {
       test.assertEqual(tab.style, null, "style of the new tab matches");
       test.assertEqual(tab.index, tabsLen, "index of the new tab matches");
       test.assertNotEqual(tab.getThumbnail(), null, "thumbnail of the new tab matches");
+      test.assertNotEqual(tab.id, null, "a tab object always has an id property");
 
       tab.close(function() {
         loader.unload();
@@ -619,3 +620,44 @@ exports.testActiveTab_getter_alt = function(test) {
     }
   });
 };
+
+exports.testUniqueTabIds = function(test) {
+  test.waitUntilDone();
+  var tabs = require('sdk/tabs');
+  var tabIds = {};
+  var steps = [
+    function (index) {
+      tabs.open({
+        url: "data:text/html;charset=utf-8,foo",
+        onOpen: function(tab) {
+          tabIds['tab1'] = tab.id;
+          next(index);
+        }
+      });
+    },
+    function (index) {
+      tabs.open({
+        url: "data:text/html;charset=utf-8,bar",
+        onOpen: function(tab) {
+          tabIds['tab2'] = tab.id;
+          next(index);
+        }
+      });
+    },
+    function (index) {
+      test.assertNotEqual(tabIds.tab1, tabIds.tab2, "Tab ids should be unique.");
+      test.done();
+    }
+  ];
+
+  function next(index) {
+    if (index === steps.length) {
+      return;
+    }
+    let fn = steps[index];
+    index++;
+    fn(index);
+  }
+
+  next(0);
+}

test/tabs/test-firefox-tabs.js

@@ -177,6 +177,7 @@ exports.testTabProperties = function(test) {
         test.assertEqual(tab.style, null, "style of the new tab matches");
         test.assertEqual(tab.index, 1, "index of the new tab matches");
         test.assertNotEqual(tab.getThumbnail(), null, "thumbnail of the new tab matches");
+        test.assertNotEqual(tab.id, null, "a tab object always has an id property.");
         closeBrowserWindow(window, function() test.done());
       }
     });
@@ -913,6 +914,53 @@ exports['test ready event on new window tab'] = function(test) {
 
   let window = openBrowserWindow(function(){}, uri);
 };
+
+exports['test unique tab ids'] = function(test) {
+  test.waitUntilDone();
+
+  var windows = require('windows').browserWindows,
+    tabIds = {}, win1, win2;
+
+  let steps = [
+    function (index) {
+      win1 = windows.open({
+          url: "data:text/html;charset=utf-8,foo",
+          onOpen: function(window) {
+            tabIds['tab1'] = window.tabs.activeTab.id;
+            next(index);
+          }
+      });
+    },
+    function (index) {
+      win2 = windows.open({
+          url: "data:text/html;charset=utf-8,foo",
+          onOpen: function(window) {
+            tabIds['tab2'] = window.tabs.activeTab.id;
+            next(index);
+          }
+      });
+    },
+    function (index) {
+      test.assertNotEqual(tabIds.tab1, tabIds.tab2, "Tab ids should be unique.");
+      win1.close();
+      win2.close();
+      test.done();
+    }
+  ];
+
+  function next(index) {
+    if (index === steps.length) {
+      return;
+    }
+    let fn = steps[index];
+    index++
+    fn(index);
+  }
+
+  // run!
+  next(0);
+}
+
 /******************* helpers *********************/
 
 // Helper for getting the active window