feat(router): added vetoable preLeave event

lib/routing/routing.dart

@@ -53,6 +53,11 @@ class RouteViewFactory {
               cfg.preEnter(e);
             }
           },
+          preLeave: (RoutePreLeaveEvent e) {
+            if (cfg.preLeave != null) {
+              cfg.preLeave(e);
+            }
+          },
           leave: cfg.leave,
           mount: (Route mountRoute) {
             if (cfg.mount != null) {
@@ -66,10 +71,10 @@ class RouteViewFactory {
 NgRouteCfg ngRoute({String path, String view, String viewHtml,
     Map<String, NgRouteCfg> mount, modules(), bool defaultRoute: false,
     RoutePreEnterEventHandler preEnter, RouteEnterEventHandler enter,
-    RouteLeaveEventHandler leave}) =>
+    RoutePreLeaveEventHandler preLeave, RouteLeaveEventHandler leave}) =>
         new NgRouteCfg(path: path, view: view, viewHtml: viewHtml, mount: mount,
             modules: modules, defaultRoute: defaultRoute, preEnter: preEnter,
-            enter: enter, leave: leave);
+            preLeave: preLeave, enter: enter, leave: leave);
 
 class NgRouteCfg {
   final String path;
@@ -80,10 +85,11 @@ class NgRouteCfg {
   final bool defaultRoute;
   final RouteEnterEventHandler enter;
   final RoutePreEnterEventHandler preEnter;
+  final RoutePreLeaveEventHandler preLeave;
   final RouteLeaveEventHandler leave;
 
   NgRouteCfg({this.view, this.viewHtml, this.path, this.mount, this.modules,
-      this.defaultRoute, this.enter, this.preEnter, this.leave});
+      this.defaultRoute, this.enter, this.preEnter, this.preLeave, this.leave});
 }
 
 /**

pubspec.lock

@@ -68,7 +68,7 @@ packages:
   route_hierarchical:
     description: route_hierarchical
     source: hosted
-    version: "0.4.20"
+    version: "0.4.21"
   source_maps:
     description: source_maps
     source: hosted

pubspec.yaml

@@ -23,7 +23,7 @@ dependencies:
   html5lib: '>=0.10.0 <0.11.0'
   intl: '>=0.8.7 <0.10.0'
   perf_api: '>=0.0.8 <0.1.0'
-  route_hierarchical: '>=0.4.18 <0.5.0'
+  route_hierarchical: '>=0.4.21 <0.5.0'
   web_components: '>=0.3.3 <0.4.0'
 dev_dependencies:
   benchmark_harness: '>=1.0.0'

test/angular_spec.dart

@@ -264,6 +264,8 @@ main() {
         "route.client.RouteLeaveEventHandler",
         "route.client.RoutePreEnterEvent",
         "route.client.RoutePreEnterEventHandler",
+        "route.client.RoutePreLeaveEvent",
+        "route.client.RoutePreLeaveEventHandler",
         "route.client.Router",
         "route.client.RouteStartEvent",
         "url_matcher.UrlMatch",

test/routing/routing_spec.dart

@@ -169,6 +169,66 @@ main() {
     }));
 
 
+    it('should call preEnter callback and be able to veto', async(() {
+      int preEnterCount = 0;
+      initRouter((Router router, RouteViewFactory views) {
+        views.configure({
+          'foo': ngRoute(
+              path: '/foo',
+              preEnter: (RoutePreEnterEvent e) {
+                preEnterCount++;
+                e.allowEnter(new Future.value(false));
+              },
+              view: 'foo.html'
+          ),
+        });
+      });
+
+      Element root = _.compile('<ng-view></ng-view>');
+      expect(root.text).toEqual('');
+
+      router.route('/foo');
+      microLeap();
+
+      expect(preEnterCount).toBe(1);
+      expect(root.text).toEqual(''); // didn't enter.
+    }));
+
+
+    it('should call preLeave callback and be able to veto', async(() {
+      int preLeaveCount = 0;
+      initRouter((Router router, RouteViewFactory views) {
+        views.configure({
+          'foo': ngRoute(
+              path: '/foo',
+              preLeave: (RoutePreLeaveEvent e) {
+                preLeaveCount++;
+                e.allowLeave(new Future.value(false));
+              },
+              view: 'foo.html'
+          ),
+        });
+      });
+      _.injector.get(TemplateCache)
+          .put('foo.html', new HttpResponse(200, '<h1>Foo</h1>'));
+
+      Element root = _.compile('<ng-view></ng-view>');
+      expect(root.text).toEqual('');
+
+      router.route('/foo');
+      microLeap();
+
+      expect(preLeaveCount).toBe(0);
+      expect(root.text).toEqual('Foo');
+
+      router.route('');
+      microLeap();
+
+      expect(preLeaveCount).toBe(1);
+      expect(root.text).toEqual('Foo'); // didn't leave.
+    }));
+
+
     it('should call preEnter callback and load modules', async(() {
       int preEnterCount = 0;
       int modulesCount = 0;