Enhancing event listener using AngularJS and Jasmine: spying on callback functions

Can someone assist me with spyOnning a method connected to an event using scope.$on in a factory service, using Jasmine? The actual method is being called instead of the spy. Here is a plinkr I created showcasing the issue: http://plnkr.co/edit/2RPwrw?p=preview

I appreciate any help you can provide. Thank you.

Answer №1

The reason for this behavior lies in the way you are attaching the callback function. Modify

service.$on('hello', service.method);

to

service.$on('hello', function() {
  service.method();
});

When using spyOn(service, 'method'), you are essentially instructing to replace the current value referenced at service.method with a spy function. However, in your original code snippet, the service.$on method does not access the value of service.method when the event is triggered. Instead, it retrieves the value during the initialization of the service. Therefore, changing the reference that service.method points to at a later point will have no impact.

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