fix(datepicker): pass through null

- When `minDate` or `maxDate` is `null` in the popup, pass through value to inline datepicker

Closes #5275
Fixes #5238

Author: wesleycho

src/datepicker/datepicker.js

@@ -685,10 +685,18 @@ function(scope, element, attrs, $compile, $parse, $document, $rootScope, $positi
 
         scope.$parent.$watch(getAttribute, function(value) {
           if (key === 'minDate' || key === 'maxDate') {
-            cache[key] = angular.isDate(value) ? dateParser.fromTimezone(new Date(value), ngModelOptions.timezone) : new Date(dateFilter(value, 'medium'));
+            if (value === null) {
+              cache[key] = null;
+            } else if (angular.isDate(value)) {
+              cache[key] = dateParser.fromTimezone(new Date(value), ngModelOptions.timezone);
+            } else {
+              cache[key] = new Date(dateFilter(value, 'medium'));
+            }
+
+            scope.watchData[key] = value === null ? null : cache[key];
+          } else {
+            scope.watchData[key] = dateParser.fromTimezone(new Date(value), ngModelOptions.timezone);
           }
-
-          scope.watchData[key] = cache[key] || dateParser.fromTimezone(new Date(value), ngModelOptions.timezone);
         });
 
         datepickerEl.attr(cameltoDash(key), 'watchData.' + key);

src/datepicker/test/datepicker.spec.js

@@ -2173,6 +2173,18 @@ describe('datepicker', function() {
             expect(buttons.eq(0).prop('disabled')).toBe(true);
           }));
 
+          it('should not disable any button if min date is null', function() {
+            $rootScope.minDate = null;
+            var wrapElement = $compile('<div><input ng-model="date" uib-datepicker-popup min-date="minDate" is-open="true"><div>')($rootScope);
+            $rootScope.$digest();
+            assignElements(wrapElement);
+            assignButtonBar();
+
+            for (var i = 0; i < buttons.length; i++) {
+              expect(buttons.eq(i).prop('disabled')).toBe(false);
+            }
+          });
+
           it('should disable today button if after max date', function() {
             $rootScope.maxDate = new Date().setDate(new Date().getDate() - 2);
             var wrapElement = $compile('<div><input ng-model="date" uib-datepicker-popup max-date="maxDate" is-open="true"><div>')($rootScope);
@@ -2183,6 +2195,18 @@ describe('datepicker', function() {
             expect(buttons.eq(0).prop('disabled')).toBe(true);
           });
 
+          it('should not disable any button if max date is null', function() {
+            $rootScope.maxDate = null;
+            var wrapElement = $compile('<div><input ng-model="date" uib-datepicker-popup max-date="maxDate" is-open="true"><div>')($rootScope);
+            $rootScope.$digest();
+            assignElements(wrapElement);
+            assignButtonBar();
+
+            for (var i = 0; i < buttons.length; i++) {
+              expect(buttons.eq(i).prop('disabled')).toBe(false);
+            }
+          });
+
           it('should remove bar', function() {
             $rootScope.showBar = false;
             var wrapElement = $compile('<div><input ng-model="date" uib-datepicker-popup show-button-bar="showBar" is-open="true"><div>')($rootScope);