How to get the rendered content from the `link` function of a directive?

Html code:

<div class="test">{{name}}</div>

Angular code:

var app = angular.module('angularjs-starter', []);

app.controller('MainCtrl', function($scope) {
  $scope.name = 'World';
});

app.directive('test', function(){
  return {
    restrict: 'C',
    link: function(scope, elm, attrs){
      var content = elm.html();
      alert(content);
    }
  }
});

It will alert a string {{name}}. How to alert the rendered string World?

Live demo: http://plnkr.co/edit/Mov0AlkdE9B8yKiBjpnp?p=preview

You need to use $interpolate service to do this

app.directive('test', function($interpolate){
  return {
    restrict: 'C',
    link: function(scope, elm, attrs){
      var content = elm.html();
      alert($interpolate(content)(scope))
    }
  }
});

Demo: Fiddle