Stubbing e.preventDefault() in a jasmine test

Question

I recently added an e.preventDefault() to one of my javascript functions and it broke my jasmine spec. I've tried spyOn(e, 'preventDefault').andReturn(true); but I get e is undefined error. How do I stub e.preventDefault()?

showTopic: function(e) {
  e.preventDefault();
  midParent.prototype.showTopic.call(this, this.model, popup);
  this.topic.render();
}

it("calls the parent", function() {
    var parentSpy = spyOn(midParent.prototype, "showTopic");
    this.view.topic = {
      render: function() {}
    };
    this.view.showTopic();
    expect(parentSpy).toHaveBeenCalled();
});

Answer 1

Another way to create mock object (with spies you need) is to use jasmine.createSpyObj(). Array containing spy names have to be passed as second parameter.

var e = jasmine.createSpyObj('e', [ 'preventDefault' ]);
this.view.showTopic(e);
expect(e.preventDefault).toHaveBeenCalled();

Answer 2

You have to pass an object with a field preventDefault that holds your spy:

var event = {preventDefault: jasmine.createSpy()}
this.view.showTopic(event);
expect(event.preventDefault).toHaveBeenCalled