fix(ngMockE2E): ensure that mocked $httpBackend uses correct $browser

The fix from #13124 enabled ngMock and ngMockE2E to work together but
did it in a way that meant that the "real" `$httpBackend` service that
was used in pass-through depended upon a different `$browser` service
to the rest of the app.

This broke Protractor since it watches the `$browser` for outstanding
requests and the pass through requests were being tracked by the wrong
`$browser` instance.

Closes #15593

Author: petebacondarwin

src/ngMock/angular-mocks.js

@@ -1313,9 +1313,8 @@ angular.mock.dump = function(object) {
       });
   ```
  */
-angular.mock.$HttpBackendProvider = function() {
-  this.$get = ['$rootScope', '$timeout', createHttpBackendMock];
-};
+angular.mock.$httpBackendDecorator =
+  ['$rootScope', '$timeout', '$delegate', createHttpBackendMock];
 
 /**
  * General factory function for $httpBackend mock.
@@ -1336,7 +1335,10 @@ function createHttpBackendMock($rootScope, $timeout, $delegate, $browser) {
       expectations = [],
       responses = [],
       responsesPush = angular.bind(responses, responses.push),
-      copy = angular.copy;
+      copy = angular.copy,
+      // We cache the original backend so that if both ngMock and ngMockE2E override the
+      // service the ngMockE2E version can pass through to the real backend
+      originalHttpBackend = $delegate.$$originalHttpBackend || $delegate;
 
   function createResponse(status, data, headers, statusText) {
     if (angular.isFunction(status)) return status;
@@ -1421,7 +1423,7 @@ function createHttpBackendMock($rootScope, $timeout, $delegate, $browser) {
           // if $browser specified, we do auto flush all requests
           ($browser ? $browser.defer : responsesPush)(wrapResponse(definition));
         } else if (definition.passThrough) {
-          $delegate(method, url, data, callback, headers, timeout, withCredentials, responseType, eventHandlers, uploadEventHandlers);
+          originalHttpBackend(method, url, data, callback, headers, timeout, withCredentials, responseType, eventHandlers, uploadEventHandlers);
         } else throw new Error('No response defined !');
         return;
       }
@@ -1897,6 +1899,8 @@ function createHttpBackendMock($rootScope, $timeout, $delegate, $browser) {
     responses.length = 0;
   };
 
+  $httpBackend.$$originalHttpBackend = originalHttpBackend;
+
   return $httpBackend;
 
 
@@ -2394,14 +2398,14 @@ angular.module('ngMock', ['ng']).provider({
   $exceptionHandler: angular.mock.$ExceptionHandlerProvider,
   $log: angular.mock.$LogProvider,
   $interval: angular.mock.$IntervalProvider,
-  $httpBackend: angular.mock.$HttpBackendProvider,
   $rootElement: angular.mock.$RootElementProvider,
   $componentController: angular.mock.$ComponentControllerProvider
 }).config(['$provide', '$compileProvider', function($provide, $compileProvider) {
   $provide.decorator('$timeout', angular.mock.$TimeoutDecorator);
   $provide.decorator('$$rAF', angular.mock.$RAFDecorator);
   $provide.decorator('$rootScope', angular.mock.$RootScopeDecorator);
   $provide.decorator('$controller', createControllerDecorator($compileProvider));
+  $provide.decorator('$httpBackend', angular.mock.$httpBackendDecorator);
 }]);
 
 /**
@@ -2416,7 +2420,6 @@ angular.module('ngMock', ['ng']).provider({
  * the {@link ngMockE2E.$httpBackend e2e $httpBackend} mock.
  */
 angular.module('ngMockE2E', ['ng']).config(['$provide', function($provide) {
-  $provide.value('$httpBackend', angular.injector(['ng']).get('$httpBackend'));
   $provide.decorator('$httpBackend', angular.mock.e2e.$httpBackendDecorator);
 }]);
 

test/ngMock/angular-mocksSpec.js

@@ -2432,13 +2432,15 @@ describe('ngMock', function() {
 
 describe('ngMockE2E', function() {
   describe('$httpBackend', function() {
-    var hb, realHttpBackend, callback;
+    var hb, realHttpBackend, realHttpBackendBrowser, callback;
 
     beforeEach(function() {
       callback = jasmine.createSpy('callback');
       angular.module('ng').config(function($provide) {
         realHttpBackend = jasmine.createSpy('real $httpBackend');
-        $provide.value('$httpBackend', realHttpBackend);
+        $provide.factory('$httpBackend', ['$browser', function($browser) {
+          return realHttpBackend.and.callFake(function() { realHttpBackendBrowser = $browser; });
+        }]);
       });
       module('ngMockE2E');
       inject(function($injector) {
@@ -2477,6 +2479,14 @@ describe('ngMockE2E', function() {
         expect(realHttpBackend).not.toHaveBeenCalled();
         expect(callback).toHaveBeenCalledOnceWith(200, 'passThrough override', '', '');
       }));
+
+      it('should pass through to an httpBackend that uses the same $browser service', inject(function($browser) {
+        hb.when('GET', /\/passThrough\/.*/).passThrough();
+        hb('GET', '/passThrough/23');
+
+        expect(realHttpBackend).toHaveBeenCalledOnce();
+        expect(realHttpBackendBrowser).toBe($browser);
+      }));
     });