Calling $digest on a jasmine test works only the first time - angularjs

Question

I'm trying to test the behavior of a 'watch' on my scope. But the problem is it's called only once. Check the fiddle below. And strangely, i noticed that if you put the variables in the controller's $scope rather than on the controller itself (aka $scope.name vs vm.name) it actually works.
Using vm (not working): http://jsfiddle.net/2Ny8x/60/
//--- CODE --------------------------
(function (angular) {
// Create module
var myApp = angular.module('myApp', []);
// Controller which counts changes to its "name" member
myApp.controller('MyCtrl', ['$scope', function ($scope) {
var vm = this;
vm.name = 'Superhero';
vm.counter = 0;
$scope.$watch('vm.name', function (newValue, oldValue) {
vm.counter = vm.counter + 1;
});
}]);
})(angular);
// ---SPECS-------------------------
describe('myApp', function () {
var scope,
controller;
beforeEach(function () {
module('myApp');
});
describe('MyCtrl', function () {
beforeEach(inject(function ($rootScope, $controller) {
scope = $rootScope.$new();
controller = $controller('MyCtrl', {
'$scope': scope
});
}));
it('sets the name', function () {
expect(controller.name).toBe('Superhero');
});
it('watches the name and updates the counter', function () {
expect(controller.counter).toBe(0);
controller.name = 'Batman';
scope.$digest();
expect(controller.counter).toBe(1);
controller.name = 'Superman';
scope.$digest();
expect(controller.counter).toBe(2);
});
});
});
Using $scope (works): http://jsfiddle.net/2Ny8x/61/
//--- CODE --------------------------
(function (angular) {
// Create module
var myApp = angular.module('myApp', []);
// Controller which counts changes to its "name" member
myApp.controller('MyCtrl', ['$scope', function ($scope) {
$scope.name = 'Superhero';
$scope.counter = 0;
$scope.$watch('name', function (newValue, oldValue) {
$scope.counter = $scope.counter + 1;
});
}]);
})(angular);
// ---SPECS-------------------------
describe('myApp', function () {
var scope,
controller;
beforeEach(function () {
module('myApp');
});
describe('MyCtrl', function () {
beforeEach(inject(function ($rootScope, $controller) {
scope = $rootScope.$new();
controller = $controller('MyCtrl', {
'$scope': scope
});
}));
it('sets the name', function () {
expect(scope.name).toBe('Superhero');
});
it('watches the name and updates the counter', function () {
expect(scope.counter).toBe(0);
scope.name = 'Batman';
scope.$digest();
expect(scope.counter).toBe(1);
scope.name = 'Superman';
scope.$digest();
expect(scope.counter).toBe(2);
});
});
});

Answer 1

You are watching for a property on the scope, which is not really the case, since you are modifying property in your controller. So change your watch to:-
$scope.$watch(function(){
return vm.name;
}, function (newValue, oldValue) {
vm.counter = vm.counter + 1;
});
Plnkr
Another way to make it work is to use controller as vm in your test while instantiating the controller, so that controller instance would be attached the scope as a property with name vm.
controller = $controller('MyCtrl as vm', {
'$scope': scope
});
Plnkr2