Sinon doesn't seem to follow the event handler callback

Question

I am testing the base view with Jasmin, Simon and jasmin-simon.

Here is the code:

var MessageContainerView = Backbone.View.extend({
    id: 'messages',
    initialize: function() {
        this.collection.bind('add', this.addMessage, this);
    },
    render: function( event ) {
        this.collection.each(this.addMessage);
        return this;
    },
    addMessage: function( message ) {
        console.log('addMessage called', message);
        var view = new MessageView({model: message});
        $('#' + this.id).append(view.render().el);
    }
});

Actually, all my tests pass, but one. I would like to check what addMessagegets called whenever I add an element to this.collection.

describe('Message Container tests', function(){
    beforeEach(function(){
        this.messageView = new Backbone.View;
        this.messageViewStub = sinon.stub(window, 'MessageView').returns(this.messageView);

        this.message1 = new Backbone.Model({message: 'message1', type:'error'});
        this.message2 = new Backbone.Model({message: 'message2', type:'success'});
        this.messages = new Backbone.Collection([
            this.message1, this.message2            
        ]); 

        this.view = new MessageContainerView({ collection: this.messages });
        this.view.render();

        this.eventSpy = sinon.spy(this.view, 'addMessage');
        this.renderSpy = sinon.spy(this.messageView, 'render');
        setFixtures('<div id="messages"></div>');
    });
    afterEach(function(){
        this.messageViewStub.restore();
        this.eventSpy.restore();
    });

    it('check addMessage call', function(){
        var message = new Backbone.Model({message: 'newmessage', type:'success'});
        this.messages.add(message);

        // TODO: this fails not being called at all
        expect(this.view.addMessage).toHaveBeenCalledOnce();
        // TODO: this fails similarly
        expect(this.view.addMessage).toHaveBeenCalledWith(message, 'Expected to have been called with `message`');
        // these pass
        expect(this.messageView.render).toHaveBeenCalledOnce();
        expect($('#messages').children().length).toEqual(1);
    });
});

As you can see, it’s addMessagereally called. (He writes to the console and calls this.messageView, as you would expect. What do I miss when spying on calls addMessage?

thanks Victor

Answer 1

I'm not sure, but as I understand it, the following happens:

• You create a new view that calls a function initializeand binds yours view.addMessageto your collection.
• , .
• view.addMessage, , . , .

, . , . Backbone, , , Backbones Collection Model.

, collection.bind , bind 'add', this.addMessage, this

initialize: function() {
    //you dont 
    this.collection.bind('add', this.addMessage, this);
},

, :

var messages = {bind:function(){}, each:function(){}}
spyOn(messages, 'bind');
spyOn(messages, 'each');
this.view = new MessageContainerView({ collection: messages });

expect(message.bind).toHaveBeenCalledWith('bind', this.view.addMessage, this.view);

this.view.render()

expect(message.each).toHaveBeenCalledWith(this.view.addMessage);

... and so on

, Backbone.

Answer 2

3:

Then you spy on view.addMessage which means you overwrite it with a spy function. Doing this will have no effect on the function that is stored in the collection event store.

, , , MessageContainerView.prototype.addMessage :

describe('Message Container tests', function(){
    beforeEach(function(){
        this.messageView = new Backbone.View;
        this.messageViewStub = sinon.stub(window, 'MessageView').returns(this.messageView);

        this.message1 = new Backbone.Model({message: 'message1', type:'error'});
        this.message2 = new Backbone.Model({message: 'message2', type:'success'});
        this.messages = new Backbone.Collection([
            this.message1, this.message2            
        ]);
        // Here
        this.addMessageSpy = sinon.spy(MessageContainerView.prototype, 'addMessage');
        this.view = new MessageContainerView({ collection: this.messages });
        this.view.render();

        this.eventSpy = sinon.spy(this.view, 'addMessage');
        this.renderSpy = sinon.spy(this.messageView, 'render');
        setFixtures('<div id="messages"></div>');
    });
    afterEach(function(){
        this.messageViewStub.restore();
        MessageContainerView.prototype.addMessage.restore();

    });

    it('check addMessage call', function(){
        var message = new Backbone.Model({message: 'newmessage', type:'success'});
        this.messages.add(message);

        // TODO: this fails not being called at all
        expect(this.addMessageSpy).toHaveBeenCalledOnce();
        // TODO: this fails similarly
        expect(this.addMessageSpy).toHaveBeenCalledWith(message, 'Expected to have been called with `message`');
        // these pass
        expect(this.messageView.render).toHaveBeenCalledOnce();
        expect($('#messages').children().length).toEqual(1);
    });
});

, .:)