fix(datepicker): correct datepicker-mode binding for popup

Fixes #2180
Closes #2184

src/datepicker/datepicker.js

@@ -30,7 +30,7 @@ angular.module('ui.bootstrap.datepicker', ['ui.bootstrap.dateparser', 'ui.bootst
     self[key] = angular.isDefined($attrs[key]) ? (index < 8 ? $interpolate($attrs[key])($scope.$parent) : $scope.$parent.$eval($attrs[key])) : datepickerConfig[key];
   });
 
-  // Watchable attributes
+  // Watchable date attributes
   angular.forEach(['minDate', 'maxDate'], function( key ) {
     if ( $attrs[key] ) {
       $scope.$parent.$watch($parse($attrs[key]), function(value) {
@@ -477,12 +477,24 @@ function ($compile, $parse, $document, $position, dateFilter, dateParser, datepi
         });
       }
 
-      angular.forEach(['minDate', 'maxDate'], function( key ) {
+      scope.watchData = {};
+      angular.forEach(['minDate', 'maxDate', 'datepickerMode'], function( key ) {
         if ( attrs[key] ) {
-          scope.$parent.$watch($parse(attrs[key]), function(value){
-            scope[key] = value;
+          var getAttribute = $parse(attrs[key]);
+          scope.$parent.$watch(getAttribute, function(value){
+            scope.watchData[key] = value;
           });
-          datepickerEl.attr(cameltoDash(key), key);
+          datepickerEl.attr(cameltoDash(key), 'watchData.' + key);
+
+          // Propagate changes from datepicker to outside
+          if ( key === 'datepickerMode' ) {
+            var setAttribute = getAttribute.assign;
+            scope.$watch('watchData.' + key, function(value, oldvalue) {
+              if ( value !== oldvalue ) {
+                setAttribute(scope.$parent, value);
+              }
+            });
+          }
         }
       });
       if (attrs.dateDisabled) {

src/datepicker/docs/demo.js

@@ -30,7 +30,6 @@ angular.module('ui.bootstrap.demo').controller('DatepickerDemoCtrl', function ($
     startingDay: 1
   };
 
-  $scope.initDate = new Date('2016-15-20');
   $scope.formats = ['dd-MMMM-yyyy', 'yyyy/MM/dd', 'dd.MM.yyyy', 'shortDate'];
   $scope.format = $scope.formats[0];
 });

src/datepicker/test/datepicker.spec.js

@@ -1597,6 +1597,25 @@ describe('datepicker directive', function () {
         }
       });
     });
+
+    describe('`datepicker-mode`', function () {
+      beforeEach(inject(function() {
+        $rootScope.date = new Date('August 11, 2013');
+        $rootScope.mode = 'month';
+        wrapElement = $compile('<div><input ng-model="date" datepicker-popup datepicker-mode="mode"></div>')($rootScope);
+        $rootScope.$digest();
+        assignElements(wrapElement);
+      }));
+
+      it('shows the correct title', function() {
+        expect(getTitle()).toBe('2013');
+      });
+
+      it('updates binding', function() {
+        clickTitleButton();
+        expect($rootScope.mode).toBe('year');
+      });
+    });
   });
 
   describe('with empty initial state', function () {