Expose $urlRouterUpdateStart event to allow deferrable update()

src/urlRouter.js

@@ -92,7 +92,8 @@ function $UrlRouterProvider(  $urlMatcherFactory) {
     [        '$location', '$rootScope', '$injector',
     function ($location,   $rootScope,   $injector) {
       // TODO: Optimize groups of rules with non-empty prefix into some sort of decision tree
-      function update() {
+      function update(evt) {
+        if (evt && evt.defaultPrevented) return;
         function check(rule) {
           var handled = rule($injector, $location);
           if (handled) {
@@ -110,7 +111,12 @@ function $UrlRouterProvider(  $urlMatcherFactory) {
       }
 
       $rootScope.$on('$locationChangeSuccess', update);
-      return {};
+
+      return {
+        sync: function () {
+          update();
+        }
+      };
     }];
 }
 

test/urlRouterSpec.js

@@ -80,6 +80,32 @@ describe("UrlRouter", function () {
       expect(custom.url.format).not.toHaveBeenCalled();
       expect(custom.handler).toHaveBeenCalled();
     });
+
+    it('can be cancelled by preventDefault() in $locationChangeSuccess', inject(function () {
+      var called;
+      location.path("/baz");
+      scope.$on('$locationChangeSuccess', function (ev) {
+        ev.preventDefault();
+        called = true;
+      });
+      scope.$emit("$locationChangeSuccess");
+      expect(called).toBeTruthy();
+      expect(location.path()).toBe("/baz");
+    }));
+
+    it('can be deferred and updated in $locationChangeSuccess', inject(function ($urlRouter, $timeout) {
+      var called;
+      location.path("/baz");
+      scope.$on('$locationChangeSuccess', function (ev) {
+        ev.preventDefault();
+        called = true;
+        $timeout($urlRouter.sync, 2000);
+      });
+      scope.$emit("$locationChangeSuccess");
+      $timeout.flush();
+      expect(called).toBeTruthy();
+      expect(location.path()).toBe("/b4z");
+    }));
   });
 
 });