Spying on function of object created within Backbone view

Question

I'm trying to spy on a Backbone view. Within one of the view function, an object is created and attached to the view:

var BackboneView = Backbone.View.extend({

    anObject: null,

    .....

    viewFunction: function() {

        if (!this.anObject) {
                    this.anObject = new theObject();
                    this.anObject.setTimeout(10);
        }
    }),

    ....
});

return BackboneView;

The object looks like this (and cannot be changed):

var theObject = function () {

    this.setTimeout = function (timeout) {
        //set timeout
    };

    return this;
});

return theObject;

I want to make sure setTimeout was called. So I tried:

    it('theObject.prototype.setTimeout called', function () {

        spyOn(theObject.prototype, 'setTimeout');

        myBackboneView.viewFunction()

        expect(theObject.prototype.setTimeout).toHaveBeenCalled();

    });

But I get the error:

    setTimeout() method does not exist

So I try to spy on it through the Backbone view:

    it('myBackboneView.anObject.setTimeout called', function () {

        spyOn(myBackboneView.anObject, 'setTimeout');

        myBackboneView.viewFunction();

        expect(myBackboneView.anObject.setTimeout).toHaveBeenCalled();

    });

But I predictably get the error:

spyOn could not find an object to spy upon for setTimeout()

Any ideas how I make sure setTimeout() was called?

Answer 1

setTimeout() method does not exist

Because you did not set setTimeout on the function prototype.

if you want a function on a prototype you need to put it on a prototype,then you can spy on the function.

theObject.prototype.setTimeout=function(){/*some code*/}

and no need to return this in the constructor.

  this.setTimeout = function (timeout) {
        //set timeout
    };

    return this; // this is wrong!!!