how do you freeze / fake time with Jasmine BDD

Question

I have a line like this in my code

new Date().getFullYear();

and I need it to always return the same year.

Is there any way to do this with Jasmine ?

Thanks.

Answer 1

In JavaScript you can simply overwrite the function in your test setup:

Date.prototype.getFullYear = function(){return 2012}

You could also use a jasmine spy:

spyOn(Date, 'getFullYear').andReturn(2012)

Another way is to insert the date into your function you wanna test. Which is btw. the best way to write testable code. Dont create new instances in your functions, cause you always start to test not only your code but also this instances.

Answer 2

Sinon.js fake timers.

http://sinonjs.org/docs/#clock

I built a drum machine in Node.js using this in my specs to check the timing code. but I also worked with it on another project where the only way I could get it to be the year I wanted was by using one specific year, I think 1969 for some reason. I'm guessing that's the start of the Unix era.

anyway, that was almost a year ago, so they've probably fixed it by now.