Refactor $browser's lazy start polling

+ unit tests

src/AngularPublic.js

@@ -12,12 +12,6 @@ angularService('$browser', function($log){
   if (!browserSingleton) {
     browserSingleton = new Browser(window, jqLite(window.document), jqLite(window.document.body),
                                    XHR, $log);
-    var addPollFn = browserSingleton.addPollFn;
-    browserSingleton.addPollFn = function(){
-      browserSingleton.addPollFn = addPollFn;
-      browserSingleton.startPoller(100, function(delay, fn){setTimeout(delay,fn);});
-      return addPollFn.apply(browserSingleton, arguments);
-    };
     browserSingleton.bind();
   }
   return browserSingleton;

src/Browser.js

@@ -141,7 +141,8 @@ function Browser(window, document, body, XHR, $log) {
   //////////////////////////////////////////////////////////////
   // Poll Watcher API
   //////////////////////////////////////////////////////////////
-  var pollFns = [];
+  var pollFns = [],
+      pollTimeout;
 
   /**
    * @workInProgress
@@ -162,11 +163,13 @@ function Browser(window, document, body, XHR, $log) {
    * @param {function()} fn Poll function to add
    *
    * @description
-   * Adds a function to the list of functions that poller periodically executes
+   * Adds a function to the list of functions that poller periodically executes,
+   * and starts polling if not started yet.
    *
    * @returns {function()} the added function
    */
   self.addPollFn = function(fn) {
+    if (!pollTimeout) self.startPoller(100, setTimeout);
     pollFns.push(fn);
     return fn;
   };
@@ -187,7 +190,7 @@ function Browser(window, document, body, XHR, $log) {
   self.startPoller = function(interval, setTimeout) {
     (function check(){
       self.poll();
-      setTimeout(check, interval);
+      pollTimeout = setTimeout(check, interval);
     })();
   };
 

test/BrowserSpecs.js

@@ -4,6 +4,7 @@ describe('browser', function(){
 
   function fakeSetTimeout(fn) {
     setTimeoutQueue.push(fn);
+    return Math.random();
   }
 
   fakeSetTimeout.flush = function() {
@@ -384,6 +385,10 @@ describe('browser', function(){
   });
 
   describe('poller', function(){
+    beforeEach(function() {
+      spyOn(browser, 'startPoller');
+    });
+
     it('should call all fns on poll', function(){
       var log = '';
       browser.addPollFn(function(){log+='a';});
@@ -399,6 +404,7 @@ describe('browser', function(){
       var log = '';
       var setTimeoutSpy = jasmine.createSpy('setTimeout');
       browser.addPollFn(function(){log+='.';});
+      browser.startPoller.andCallThrough();
       browser.startPoller(50, setTimeoutSpy);
       expect(log).toEqual('.');
       expect(setTimeoutSpy.mostRecentCall.args[1]).toEqual(50);
@@ -411,6 +417,22 @@ describe('browser', function(){
       var returnedFn = browser.addPollFn(fn);
       expect(returnedFn).toBe(fn);
     });
+
+    it('should auto start poller when first fn registered', function() {
+      browser.addPollFn(function() {});
+
+      expect(browser.startPoller).toHaveBeenCalled();
+      expect(browser.startPoller.callCount).toBe(1);
+    });
+
+    it('should auto start poller only when first fn registered', function() {
+      browser.startPoller.andCallThrough();
+      browser.addPollFn(function() {});
+      browser.addPollFn(function() {});
+      browser.addPollFn(function() {});
+
+      expect(browser.startPoller.callCount).toBe(1);
+    });
   });
 
 
@@ -424,6 +446,7 @@ describe('browser', function(){
       };
 
       browser = new Browser(fakeWindow, {}, {});
+      browser.startPoller = function() {};
 
       var events = [];