Why Jasmine Spy Doesn't Resolve The Function Object By Reference?

I have the following simple service app.factory('Shoes', function() { function a() {return 12;} function b() {return a();} return { a: a, b: b } })

Solution 1:

After you call spyOn(service, 'a'), service.a is no longer the a you defined in the function -- it is a spy function. That spy function happens to call a, but it is not a; it has a different identity and is a different function.

However, setting the a property of service does not change the function a you declared inside app.factory. You've simply changed service so that its a property no longer refers to your original a. By contrast, your b function never changes its reference to the original a. It gets a straight from the local app.factory scope in which a and b were originally declared. The fact that service replaces its original a with a spy does not affect b's call to a(), because it does not refer to service.a.