fix(partial loader): add check for added/removed part while refreshing

While the partial loader is refreshing all parts (implictiy invoked by
a language change), any additional part will be missed and added again.

Fixes #1781

src/service/loader-partial.js

@@ -299,8 +299,8 @@ function $translatePartialLoader() {
    *
    * @throws {TypeError}
    */
-  this.$get = ['$rootScope', '$injector', '$q', '$http',
-    function ($rootScope, $injector, $q, $http) {
+  this.$get = ['$rootScope', '$injector', '$q', '$http', '$log',
+    function ($rootScope, $injector, $q, $http, $log) {
 
       /**
        * @ngdoc event
@@ -344,15 +344,39 @@ function $translatePartialLoader() {
           part.urlTemplate = part.urlTemplate || options.urlTemplate;
         });
 
+        // workaround for #1781
+        var structureHasBeenChangedWhileLoading = false;
+        var dirtyCheckEventCloser = $rootScope.$on('$translatePartialLoaderStructureChanged', function () {
+          structureHasBeenChangedWhileLoading = true;
+        });
+
         return $q.all(loaders)
           .then(function () {
+            dirtyCheckEventCloser();
+            if (structureHasBeenChangedWhileLoading) {
+              if (!options.__retries) {
+                // the part structure has been changed while loading (the origin ones)
+                // this can happen if an addPart/removePart has been invoked right after a $translate.use(lang)
+                // TODO maybe we can optimize this with the actual list of missing parts
+                options.__retries = (options.__retries || 0) + 1;
+                return service(options);
+              } else {
+                // the part structure has been changed again while loading (retried one)
+                // because this could an infinite loop, this will not load another one again
+                $log.warn('The partial loader has detected a multiple structure change (with addPort/removePart) ' +
+                  'while loading translations. You should consider using promises of $translate.use(lang) and ' +
+                  '$translate.refresh(). Also parts should be added/removed right before an explicit refresh ' +
+                  'if possible.');
+              }
+            }
             var table = {};
             prioritizedParts = getPrioritizedParts();
             angular.forEach(prioritizedParts, function (part) {
               deepExtend(table, part.tables[options.key]);
             });
             return table;
           }, function () {
+            dirtyCheckEventCloser();
             return $q.reject(options.key);
           });
       };

test/unit/service/translate.partialLoader.spec.js

@@ -0,0 +1,76 @@
+/* jshint camelcase: false, quotmark: false, unused: false */
+/* global inject: false */
+'use strict';
+
+describe('pascalprecht.translate', function () {
+
+  beforeEach(module('ngMockE2EAsync'));
+
+  beforeEach(module('pascalprecht.translate', function ($translateProvider, $translatePartialLoaderProvider) {
+    $translateProvider.useLoader('$translatePartialLoader', {
+      urlTemplate : '/locales/{part}-{lang}.json'
+    });
+    $translatePartialLoaderProvider.addPart('part1');
+    $translateProvider.use('en');
+  }));
+
+  module(function ($provide) {
+    //Randomly delay $http response to simulate real-world scenario.
+    $provide.decorator('$httpBackend', function ($delegate) {
+      var proxy = function (method, url, data, callback, headers) {
+        var interceptor = function () {
+          var _this = this,
+            _arguments = arguments,
+            _timeout = Math.floor((Math.random() * 50) + 1);
+          console.log('setting timeout to', _timeout);
+          setTimeout(function () {
+            callback.apply(_this, _arguments);
+          }, _timeout);
+        };
+        return $delegate.call(this, method, url, data, interceptor, headers);
+      };
+      for (var key in $delegate) {
+        proxy[key] = $delegate[key];
+      }
+      return proxy;
+    });
+  });
+
+  describe('using partial-loader', function () {
+
+    it('and one part right before $translate.use(…)', inject(function ($translatePartialLoader, $httpBackend, $translate, $timeout) {
+
+      $httpBackend.whenGET('/locales/part1-en.json').respond(200, '{"key1":"value1","key2":"value2","key3":"value3","key4":"value4"}');
+
+      $translate(['key1', 'key2', 'key3'])
+        .then(function (translations) {
+          expect(translations.key1).toEqual('value1');
+          expect(translations.key2).toEqual('value2');
+          expect(translations.key3).toEqual('value3');
+          console.log(translations);
+        });
+
+      $timeout.flush();
+
+    }));
+
+    // #1781
+    it('additional part right after $translate.use(…)', inject(function ($translatePartialLoader, $httpBackend, $translate, $timeout) {
+
+      $translatePartialLoader.addPart('part2');
+
+      $httpBackend.whenGET('/locales/part1-en.json').respond(200, '{"key1":"value1","key2":"value2","key3":"value3","key4":"value4"}');
+      $httpBackend.whenGET('/locales/part2-en.json').respond(200, '{"key2" : "overridenby2","key4":"overridenby2"}');
+
+      $translate(['key1', 'key2', 'key3'])
+        .then(function (translations) {
+          expect(translations.key1).toEqual('value1');
+          expect(translations.key2).toEqual('overridenby2');
+          expect(translations.key3).toEqual('value3');
+        });
+
+      $timeout.flush();
+
+    }));
+  });
+});