JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.5.3/angular.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.5.3/angular-messages.js"></script>
<div ng-app="test">
  <form-group classList="sample-class"></form-group>
</div>

JavaScript

angular.module('test', ['ngMessages'])
  .directive('formGroup', function() {
    return {
      scope: {
        classList: '='
      },
      replace: true,
      template: '<div class=\"container\" ng-class=\"classList\" ng-form=\"fg_{{$id}}\"><input type=\"text\" name=\"testInput\" ng-model=\"testValue\"  required><div ng-messages=\"this[\'fg_\' + $id].$error\"><p ng-message=\"required\">Something is wrong!<\/p><\/div><\/div>'
    }
  });