Question

57

Spying on a constructor using Jasmine

rated 0 times [ 63] [ 6] / answers: 1 / hits: 79864 / 13 Years ago, sun, february 19, 2012, 12:00:00

I am using Jasmine to test if certain objects are created and methods are called on them.

I have a jQuery widget that creates flipcounter objects and calls the setValue method on them. The code for flipcounter is here: https://bitbucket.org/cnanney/apple-style-flip-counter/src/13fd00129a41/js/flipcounter.js

The flipcounters are created using:

var myFlipCounter = new flipCounter(counter, {inc: 23, pace: 500});

I want to test that the flipcounters are created and the setValue method is called on them. My problem is that how do I spy on these objects even before they are created? Do I spy on the constructor and return fake objects? Sample code would really help. Thanks for your help! :)

Update:

I've tried spying on the flipCounter like this:

myStub = jasmine.createSpy('myStub');

spyOn(window, 'flipCounter').andReturn(myStub);



//expectation

expect(window.flipCounter).toHaveBeenCalled();

Then testing for the setValue call by flipCounter:

spyOn(myStub, 'setValue');



//expectation

expect(myStub.setValue).toHaveBeenCalled();

the first test for initializing flipCounter is fine, but for testing the setValue call, all I'm getting is a 'setValue() method does not exist' error. Am I doing this the right way? Thanks!

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maxh

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2 Years ago

answered 13 Years ago kaleyv · Accepted Answer

flipCounter is just another function, even if it also happens to construct an object. Hence you can do:

var cSpy = spyOn(window, 'flipCounter');

to obtain a spy on it, and do all sorts of inspections on it or say:

var cSpy = spyOn(window, 'flipCounter').andCallThrough();

var counter = flipCounter('foo', options);

expect(cSpy).wasCalled();

However, this seems overkill. It would be enough to do:

var myFlipCounter = new flipCounter(counter, options);

expect(myFlipCounter).toBeDefined();

expect(myFlipCounter.getValue(foo)).toEqual(bar);