Should I mock ALL external Services in angular?

I'm currently getting started with angular unit testing. As the first controller I wanted to tes looked like this, I got confused.

angular.module('sgmPaperApp')
  .controller('AccountCtrl', function ($mdToast, user, $firebaseArray, Ref) {
var vm = this;
vm.data = user;
vm.save = saveUser;
vm.comments = $firebaseArray(Ref.child('comments').orderByChild('person').equalTo(user.$id));


function saveUser() {
  vm.data.$save().then(function () {
    $mdToast.showSimple('Data saved');
  });
}
});

Should I really mock all external services I use? After all that controller isn't very much more then external services and mocking the firebaseArray could be difficult.

Thanks for your advice and helping me get started with testing