Unit testing Angular bootstrapping code

I have an app that uses manual bootstrapping, with a chunk of code that essentially looks like this:

(function() {
    'use strict';
        angular.element( document ).ready( function () {

            function fetchLabels( sLang, labelPath ) {
                // retrieves json files, builds an object and injects a constant into an angular module
            }

            function rMerge( oDestination, oSource ) {
                // recursive deep merge function
            }

            function bootstrapApplication() {
                angular.element( document ).ready( function () {
                    angular.bootstrap( document, [ 'dms.webui' ] );
                });
            }

            fetchLabels( 'en_AU' ).then( bootstrapApplication );

        }

It works great - essentially fetches two json files, combines them and injects the result as a constant, then bootstraps the app.

My question is how to unit test these functions? I want to write something to test the fetchLabels() and rMerge() methods, but I'm not sure how to go about it. My first thought was separate the methods out into a service and use it that way, but I wasn't sure if I could actually invoke my own service this way before I've even bootstrapped the application?

Otherwise, can anyone suggest a way to separate out these methods into something standalone that I can test more readily?