I get the error
Unknown provider: $userProvider <- $user"
With following code:
var app = angular.module('test', []);
app.factory("user", function($scope, $http) {
   var usr = {};
   usr.getAllLists = function(){
       return "test";
   }
   return usr;  
});
cart.controller("MyController", ["$scope", "$http", "$user", 
    function ($scope, $http, user){
        $scope.initialize = function(){
            $scope.lists = user.getAllLists();
        }
    }
]);
Do you see the mistake?
 
                        
Assuming cart is having dependency on app module.
It has to be user and not
$user.Also, in factory, in place of
$scope, use$rootScope.