Try to change the
$scope.testField
into
$scope.myModel.testField
(oruser.firstName
…)
As mentioned in this video angular JS – best practice (29:19):
“Whenever you have ng-model there’s gotta be a dot in there somewhere. If you don’t have a dot, you’re doing it wrong.”
See updated plunker http://plnkr.co/edit/z1ABPEUB7Nxm1Kxey9iv?p=preview
NOTE: with a nice reminder of the video-minute from article Nested Scopes in Angular JS