Jasmine.js Testing - spy on window.open

Question

JS

var link = this.notificationDiv.getElementsByTagName('a')[0];

link.addEventListener('click', function (evt){
    evt.preventDefault();
    visitDestination(next);
  }, false);
}

var visitDestination = function(next){
    window.open(next)
}

Spec

  var next = "http://www.example.com"

  it( 'should test window open event', function() {

    var spyEvent = spyOnEvent('#link', 'click' ).andCallFake(visitDestination(next));;
    $('#link')[0].click();
    expect( 'click' ).toHaveBeenTriggeredOn( '#link' );
    expect( spyEvent ).toHaveBeenTriggered();

    expect(window.open).toBeDefined();
    expect(window.open).toBe('http://www.example.com');    
 });

How to write the spec to test for when link is clicked it calls visitDestination and to ensures window.open == next? When I try to run the spec it opens the new window.

Answer 1

So, window.open is a method provided by the browser. I don't believe it resets the value of itself. So this:

expect(window.open).toBe('http://www.example.com');  

... is going to fail no matter what.

What you want is to create a mock of the window.open method:

spyOn(window, 'open')

This will allow you to track when it has been run. It will also prevent the actual window.open function from running. So a new window will not open when you run the test.

Next you should test that the window.open method was run:

expect(window.open).toHaveBeenCalledWith(next)

Edit: More detail. If you want to test that visitDestination has been run then you would do:

spyOn(window, 'visitDestination').and.callThrough()

...

expect(window.visitDestination).toHaveBeenCalled()

The .and.callThrough() is really important here. If you don't use it then the normal visitDestination will be replace with a dummy/mock function which does nothing.