Question

I am writing a jasmine spec against my backbone app. However, I got stuck with this problem. Not sure why my spy function doesn’t get invoked. I want to make sure when the model is changed, it should call #render.

Here is my backbone view:

class App.Views.Main extends Backbone.View
  initialize: () ->
    @model.on("change", @render, this)

  render: () ->
    console.log('rendering')
    return

Here is my jasmine spec:

it "should render when change is triggered", ->
  renderSpy = sinon.spy(@view, 'render')
  @view.model.trigger('change')

  expect(renderSpy.called).toBeTruthy()

Another thing that confuses me is that when this spec runs, it actually invokes the original method. The console log is always displayed. Anyone could help me?

Updated:

As answered below by Leonardo, I make changes with the following changes:

it "should render when reset is triggered", ->
  renderSpy = sinon.spy(App.Views.Main.prototype, 'render')
  @view.model.trigger('change')

  expect(@renderSpy.called).toBeTruthy()
  renderSpy.restore()

It works, but the problem is that it invokes the original method. I just wonder why?

Answer 1

I think this is the same that is happenning here:

https://stackoverflow.com/a/9012788/603175

Basically, you need to create the spy before you execute the constructor that executes the event listening, which binds the function to ‘this’ context.