How i can test callback in jasmine

I have class SomeClass with method SomeClass.fetch()

var repository = {
    get: function(obj) {
        //...
    }
};

var cache = false;

var SomeClass = {

    init: function() {
        //...
    },

    fetch: function () {
        var _this = this;

        repository.get({
            method: 'getRecentDialogsList',
            success: function (result) {
                if (!cache) {
                    _this.set(result);
                    _this.sort();
                    _this.trigger('fetch:success', _this);
                }

                _this.trigger('fetch:ajaxSuccess', _this);
            }
        });
    }
}

How i can test SomeClass.fetch() and check have been called this.set(), this.sort, this.trigger with params?