Tab active function fix

src/tabs/tabs.js

@@ -186,7 +186,8 @@ angular.module('ui.bootstrap.tabs', [])
         var getActive, setActive;
         if (attrs.active) {
           getActive = $parse(attrs.active);
-          setActive = getActive.assign;
+          setActive = getActive.assign || angular.noop;
+
           scope.$parent.$watch(getActive, function updateActive(value, oldVal) {
             // Avoid re-initializing scope.active as it is already initialized
             // below. (watcher is called async during init with value ===

src/tabs/test/tabs.spec.js

@@ -473,6 +473,36 @@ describe('tabs', function() {
     }));
   });
 
+  describe('active', function() {
+    var generateElm;
+
+    beforeEach(inject(function($compile, $rootScope) {
+      scope = $rootScope.$new();
+
+      generateElm = function(activeAttr) {
+        elm = $compile([
+          '<tabset>',
+          '  <tab active="' + activeAttr + '">',
+          '    <tab-heading><b>heading</b></tab-heading>',
+          '  </tab>',
+          '</tabset>'
+        ].join('\n'))(scope);
+
+        scope.$apply();
+
+        return elm;
+      };
+    }));
+
+    it('should allow a function as an argument', function() {
+      scope.isActive = jasmine.createSpy();
+
+      elm = generateElm('isActive()');
+
+      expect(scope.isActive).toHaveBeenCalled();
+    });
+  });
+
   describe('disabled', function() {
     beforeEach(inject(function($compile, $rootScope) {
       scope = $rootScope.$new();