feat(router): enforce convention of CamelCase names in route aliases

Closes #4083

modules/angular2/src/router/route_recognizer.ts

@@ -44,6 +44,12 @@ export class RouteRecognizer {
   config(config: RouteDefinition): boolean {
     var handler;
 
+    if (isPresent(config.as) && config.as[0].toUpperCase() != config.as[0]) {
+      var suggestedAlias = config.as[0].toUpperCase() + config.as.substring(1);
+      throw new BaseException(
+          `Route '${config.path}' with alias '${config.as}' does not begin with an uppercase letter. Route aliases should be CamelCase like '${suggestedAlias}'.`);
+    }
+
     if (config instanceof AuxRoute) {
       handler = new SyncRouteHandler(config.component, config.data);
       let path = config.path.startsWith('/') ? config.path.substring(1) : config.path;

modules/angular2/test/router/route_config_spec.ts

@@ -144,6 +144,20 @@ export function main() {
                      async.done();
                      return null;
                    })}));
+
+    it('should throw if a config has an invalid alias name',
+       inject(
+           [AsyncTestCompleter],
+           (async) => {
+               bootstrap(BadAliasCmp,
+                         [bind(ROUTER_PRIMARY_COMPONENT).toValue(BadAliasCmp), testBindings])
+                   .catch((e) => {
+                     expect(e.originalException)
+                         .toContainError(
+                             `Route '/child' with alias 'child' does not begin with an uppercase letter. Route aliases should be CamelCase like 'Child'.`);
+                     async.done();
+                     return null;
+                   })}));
   });
 }
 
@@ -201,6 +215,12 @@ class HierarchyAppCmp {
 class WrongConfigCmp {
 }
 
+@Component({selector: 'app-cmp'})
+@View({template: `root { <router-outlet></router-outlet> }`, directives: ROUTER_DIRECTIVES})
+@RouteConfig([{path: '/child', component: HelloCmp, as: 'child'}])
+class BadAliasCmp {
+}
+
 @Component({selector: 'app-cmp'})
 @View({template: `root { <router-outlet></router-outlet> }`, directives: ROUTER_DIRECTIVES})
 @RouteConfig([

modules/angular2/test/router/route_recognizer_spec.ts

@@ -127,6 +127,14 @@ export function main() {
     });
 
 
+    it('should throw if the route alias is not CamelCase', () => {
+      expect(() => recognizer.config(
+                 new Route({path: 'app/user/:name', component: DummyCmpA, as: 'user'})))
+          .toThrowError(
+              `Route 'app/user/:name' with alias 'user' does not begin with an uppercase letter. Route aliases should be CamelCase like 'User'.`);
+    });
+
+
     describe('params', () => {
       it('should recognize parameters within the URL path', () => {
         recognizer.config(new Route({path: 'profile/:name', component: DummyCmpA, as: 'User'}));