How would I test a $scope.watch (AngularJS) change in Jasmine?

Question

I've just recently started writing something with AngularJS and I'm not sure how to go about writing a test for this particular thing. I'm building a "Help Request" mode that has different states. So in my controller, I use a $scope.request_mode variable. The different links to activate help requests set that variable to something differently.

Then inside my directive, I'm doing a $scope.$watch('request_mode', function(){...}); to selectively activate or deactivate things as the request mode changes. The code all works great, but the problem I'm having is with testing. I cannot seem to get Jasmine to pick up the $scope.$watch and actually fire anything when it changes.

I'm sure someone has run into this before, so any suggestions would be very much appreciated.

Solution

In your unit tests you need to manually call $scope.$digest() or $scope.$apply() to trigger $scope.$watch().

Normally in your code you wouldn't have to do this, since directives like ng-click do $rootScope.$apply for you behind the scenes.

Comments

[Anonymous]

that needs to be marked as answer, scope.$apply() works for me

[nymo]

Is it ever the case that $apply has to be called twice? I.e. once before changing the watched value and once again after, else my expectations are false. I can't find an example in which someone had called it twice.

[Volker Rose]

Yes, calling it twice was also necessary for me within one of my tests.