Unit testing an AngularJS service with angular-translate calls

I've tried numerous different ways of writing a unit test for an AngularJS service that calls angular-translate, and I just can't get it to work out. Any advice would be appreciated. Here's my most promising example:

(function() {
    var app = angular.module("theApp", ["pascalprecht.translate"]);

    var theService = function($translate) {
        var theFunction = function(data) {
            return $translate("FOO", { input: data.in }).then(function(trans) {
                data.out = trans;
            });
        };

        return {
            theFunction: theFunction
        };
    };

    app.factory("theService", ["$translate", theService]);
}());

describe("theService", function() {
    beforeEach(module("theApp", function($translateProvider, $provide) {
        $translateProvider.useLoader('customLoader');
        $provide.service('customLoader', function($q) {
            return function() {
                var deferred = $q.defer();
                deferred.resolve({
                    "FOO": "foo {{input}}"
                });
                return deferred.promise;
            };
        });
    }));

    it("function translates input", inject(function($rootScope, theService) {
        var data = { in: "bar", out: "fail" };
        theService.theFunction(data);
        $rootScope.$apply();
        expect(data.out).toBe("foo bar");
    }));
});

A JSFiddle can be found here: http://ift.tt/1xAsOAM