Expected a spy, but got Function

Question

I am trying to implement a test (1) for this module (2).
My purpose is to check if the collection is fetched when a particular event is triggered.
As you can see from my comment in (2) I get the message Error: Expected a spy, but got Function.
The module works but the test fails. any ideas?

---

(1)

// jasmine test module

describe('When onGivePoints is fired', function () {
    beforeEach(function () {
        spyOn(this.view.collection, 'restartPolling').andCallThrough();
        app.vent.trigger('onGivePoints');
    });
    it('the board collection should be fetched', function () {
        expect(this.view.collection.restartPolling).toHaveBeenCalled();
       // Error: Expected a spy, but got Function.
    });
});

---

(2)

// model view module
return Marionette.CompositeView.extend({
    initialize: function () {
        this.collection = new UserBoardCollection();
        this.collection.startPolling();
        app.vent.on('onGivePoints', this.collection.restartPolling);
    },
    // other code
});

Solution 1

You need to get into the actual method, which in this case is on the prototype.

describe('When onGivePoints is fired', function () {
    beforeEach(function () {
        spyOn(UsersBoardCollection.prototype, 'restartPolling').andCallThrough();
        app.vent.trigger('onGivePoints');
    });
    it('the board collection should be fetched', function () {
        expect(UsersBoardCollection.prototype.restartPolling).toHaveBeenCalled();
    });
});

Spying on the prototype is a nice trick you can use when you can't get to the actual instance you want to spy on.

Solution 2

I was also getting the same issue but I resolved it by passing an argument in the function call. Then you have to write your test case like this in the it

var data = {name:"test"}
spyOn(UsersBoardCollection.prototype, "restartPolling").and.callThrough();
UsersBoardCollection.prototype.restartPolling(data);
expect(UsersBoardCollection.prototype.restartPolling).toHaveBeenCalled();

Comments

[zero_cool]

if the function does not exist on the prototype, and is a function inside a React class, is this expected to work?

[Rebai Ahmed]

Why this prototype?

[Rebai Ahmed]

It's mentioned in the official docs?