How do I invoke a factory constructor with angular.mocks.inject?

Consider this code:

beforeEach(inject(function (_User_) {
    user = _User_;
}));

And this module/service:

angular.module('app.userModule', [])
.factory('User', function() {
    function User(data) {
        data.forEach(function (attr) {
            if (data.hasOwnProperty(attr))
                this[attr] = data[attr];
        })
    };

    User.prototype.getSomeAttr() { return this.attr; }

    return User;
};

How on earth can I pass 'data' into the User function constructor, using inject?

Edit: my example is derived from code here: http://sauceio.com/index.php/2014/07/angularjs-data-models-http-vs-resource-vs-restangular/