Add the ability to get the Javascript console errors in Firefox in the test output when tests fail.

tools/testing/extensions/firefox/ConsoleCollector/chrome/content/console.js

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+

[Emily Fortuna, 2012/10/04 21:13:48]

Can you add an overall explanatory comment at the top of this file giving
context for how it's used?
Thanks!

+var ConsoleCollector = {};
+ 
+(function() {
+  // An arry for collecting the messages.

[Emily Fortuna, 2012/10/04 21:13:48]

typo: array

+  var messages = [];
+
+  // Add a console message to the collection.
+  this.add = function(message) {
+    messages.push(message);
+  };
+
+  // Read the message collection. As a side effect we clear the message list.
+  this.read = function(type) {
+    var rtn = [];
+    for (var i = 0; i < messages.length; i++) {
+      var message = messages[i];
+      rtn.push({ 'time' : message.timeStamp,
+                 'source' : message.sourceName,
+                 'line': message.lineNumber,
+                 'column': message.columnNumber,
+                 'category': message.category,
+                 'message' : message.errorMessage });
+    }
+    messages = [];
+    return rtn;
+  };
+
+  // Clear the message list.
+  this.clear = function() {
+    messages = [];
+  };
+}).apply(ConsoleCollector);
+
+// A Console Listener.
+// See https://developer.mozilla.org/en-US/docs/Console_service for
+// details.
+(function() {
+
+  var consoleService;
+
+  var consoleListener = {
+    observe: function(e) {
+      try {
+        var message = e.QueryInterface(Components.interfaces.nsIScriptError);
+        ConsoleCollector.add(message);
+      } catch (exception) {
+        ConsoleCollector.add(e);
+      }      
+    },
+
+    QueryInterface: function (iid) {
+      if (!iid.equals(Components.interfaces.nsIConsoleListener) &&
+      !iid.equals(Components.interfaces.nsISupports)) {
+        throw Components.results.NS_ERROR_NO_INTERFACE;
+      }
+      return this;
+    }
+  };
+  
+  // Start collecting console messages.
+  function initialize(event) {
+    consoleService = Components.classes['@mozilla.org/consoleservice;1']
+                   .getService(Components.interfaces.nsIConsoleService);
+    if (consoleService) {
+      consoleService.registerListener(consoleListener); 
+    }                              
+  }
+
+  // Stop collecting console messages.
+  function shutdown(event) {
+    consoleService.unregisterListener(consoleListener);   
+  }
+  
+  // Hook the ConsoleCollector into the DOM as window.ConsoleCollector.
+  var onPageLoad = function(e) {
+    var win = e.originalTarget.defaultView;
+    if (win) {
+      win.wrappedJSObject.ConsoleCollector = ConsoleCollector;
+    }
+  };
+
+  // Add the handler for hooking in to each page's DOM. This handler
+  // is for each "gBrowser", representing a tab/window.
+  window.getBrowser().addEventListener("load", onPageLoad, true);
+  // Add the handlers to initialize the add-on and shut it down.
+  // These handlers are for the application as a whole.
+  window.addEventListener('load', initialize, false);
+  window.addEventListener('unload', shutdown, false);
+}());
+
+
+