feat($templateRequest): introduce the $templateRequest service

This handy service is designed to download and cache template contents
and to throw an error when a template request fails.

BREAKING CHANGE

Angular will now throw a $compile minErr each a template fails to download
for ngView, directives and ngMessage template requests. This changes the former
behavior of silently ignoring failed HTTP requests--or when the template itself
is empty. Please ensure that all directive, ngView and ngMessage code now properly
addresses this scenario. NgInclude is uneffected from this change.

test/ng/directive/ngIncludeSpec.js

@@ -199,6 +199,7 @@ describe('ngInclude', function() {
     $rootScope.url = 'url2';
     $rootScope.$digest();
     $httpBackend.flush();
+
     expect($rootScope.$$childHead).toBeFalsy();
     expect(element.text()).toBe('');
 

test/ng/templateRequestSpec.js

@@ -0,0 +1,89 @@
+'use strict';
+
+describe('$templateRequest', function() {
+
+  it('should download the provided template file',
+    inject(function($rootScope, $templateRequest, $httpBackend) {
+
+    $httpBackend.expectGET('tpl.html').respond('<div>abc</div>');
+
+    var content;
+    $templateRequest('tpl.html').then(function(html) { content = html; });
+
+    $rootScope.$digest();
+    $httpBackend.flush();
+
+    expect(content).toBe('<div>abc</div>');
+  }));
+
+  it('should cache the request using $templateCache to prevent extra downloads',
+    inject(function($rootScope, $templateRequest, $templateCache) {
+
+    $templateCache.put('tpl.html', 'matias');
+
+    var content;
+    $templateRequest('tpl.html').then(function(html) { content = html; });
+
+    $rootScope.$digest();
+    expect(content).toBe('matias');
+  }));
+
+  it('should throw an error when the template is not found',
+    inject(function($rootScope, $templateRequest, $httpBackend) {
+
+    $httpBackend.expectGET('tpl.html').respond(404);
+
+    $templateRequest('tpl.html');
+
+    $rootScope.$digest();
+
+    expect(function() {
+      $rootScope.$digest();
+      $httpBackend.flush();
+    }).toThrowMinErr('$compile', 'tpload', 'Failed to load template: tpl.html');
+  }));
+
+  it('should throw an error when the template is empty',
+    inject(function($rootScope, $templateRequest, $httpBackend) {
+
+    $httpBackend.expectGET('tpl.html').respond('');
+
+    $templateRequest('tpl.html');
+
+    $rootScope.$digest();
+
+    expect(function() {
+      $rootScope.$digest();
+      $httpBackend.flush();
+    }).toThrowMinErr('$compile', 'tpload', 'Failed to load template: tpl.html');
+  }));
+
+  it('should keep track of how many requests are going on',
+    inject(function($rootScope, $templateRequest, $httpBackend) {
+
+    $httpBackend.expectGET('a.html').respond('a');
+    $httpBackend.expectGET('b.html').respond('c');
+    $templateRequest('a.html');
+    $templateRequest('b.html');
+
+    expect($templateRequest.totalPendingRequests).toBe(2);
+
+    $rootScope.$digest();
+    $httpBackend.flush();
+
+    expect($templateRequest.totalPendingRequests).toBe(0);
+
+    $httpBackend.expectGET('c.html').respond(404);
+    $templateRequest('c.html');
+
+    expect($templateRequest.totalPendingRequests).toBe(1);
+    $rootScope.$digest();
+
+    try {
+      $httpBackend.flush();
+    } catch(e) {}
+
+    expect($templateRequest.totalPendingRequests).toBe(0);
+  }));
+
+});

test/ngRoute/directive/ngViewSpec.js

@@ -56,7 +56,7 @@ describe('ngView', function() {
   });
 
 
-  it('should instantiate controller for empty template', function() {
+  it('should not instantiate the associated controller when an empty template is downloaded', function() {
     var log = [], controllerScope,
         Ctrl = function($scope) {
           controllerScope = $scope;
@@ -70,11 +70,12 @@ describe('ngView', function() {
     inject(function($route, $rootScope, $templateCache, $location) {
       $templateCache.put('/tpl.html', [200, '', {}]);
       $location.path('/some');
-      $rootScope.$digest();
 
-      expect(controllerScope.$parent).toBe($rootScope);
-      expect(controllerScope).toBe($route.current.scope);
-      expect(log).toEqual(['ctrl-init']);
+      expect(function() {
+        $rootScope.$digest();
+      }).toThrowMinErr('$compile', 'tpload', 'Failed to load template: /tpl.html');
+
+      expect(controllerScope).toBeUndefined();
     });
   });
 

test/ngRoute/routeSpec.js

@@ -671,35 +671,36 @@ describe('$route', function() {
     });
 
 
-    it('should drop in progress route change when new route change occurs and old fails', function() {
-      module(function($routeProvider) {
+    it('should throw an error when a template is empty or not found', function() {
+      module(function($routeProvider, $exceptionHandlerProvider) {
+        $exceptionHandlerProvider.mode('log');
         $routeProvider.
           when('/r1', { templateUrl: 'r1.html' }).
-          when('/r2', { templateUrl: 'r2.html' });
+          when('/r2', { templateUrl: 'r2.html' }).
+          when('/r3', { templateUrl: 'r3.html' });
       });
 
-      inject(function($route, $httpBackend, $location, $rootScope) {
-        var log = '';
-        $rootScope.$on('$routeChangeError', function(e, next, last, error) {
-          log += '$failed(' + next.templateUrl + ', ' + error.status + ');';
-        });
-        $rootScope.$on('$routeChangeStart', function(e, next) { log += '$before(' + next.templateUrl + ');'; });
-        $rootScope.$on('$routeChangeSuccess', function(e, next) { log += '$after(' + next.templateUrl + ');'; });
-
+      inject(function($route, $httpBackend, $location, $rootScope, $exceptionHandler) {
         $httpBackend.expectGET('r1.html').respond(404, 'R1');
-        $httpBackend.expectGET('r2.html').respond('R2');
-
         $location.path('/r1');
         $rootScope.$digest();
-        expect(log).toBe('$before(r1.html);');
-
-        $location.path('/r2');
-        $rootScope.$digest();
-        expect(log).toBe('$before(r1.html);$before(r2.html);');
 
         $httpBackend.flush();
-        expect(log).toBe('$before(r1.html);$before(r2.html);$after(r2.html);');
-        expect(log).not.toContain('$after(r1.html);');
+        expect($exceptionHandler.errors.pop().message).toContain("[$compile:tpload] Failed to load template: r1.html");
+
+        $httpBackend.expectGET('r2.html').respond('');
+        $location.path('/r2');
+        $rootScope.$digest();
+
+        $httpBackend.flush();
+        expect($exceptionHandler.errors.pop().message).toContain("[$compile:tpload] Failed to load template: r2.html");
+
+        $httpBackend.expectGET('r3.html').respond('abc');
+        $location.path('/r3');
+        $rootScope.$digest();
+
+        $httpBackend.flush();
+        expect($exceptionHandler.errors.length).toBe(0);
       });
     });