text: // BEGIN-SNIPPET required-validation-rule
  import Ember from 'ember';
  import validationRule from 'computed-validator/validation-rule';
  import ValidationError from 'computed-validator/validation-error';
  const { get } = Ember;
  
  /**
   * Validate that a property is present.
   *
   * @module
   * @public
   * @return {object} validationBuilder
   */
  export default validationRule(function(args, { onProperty }) {
    let error = new ValidationError('validations.required', { property: onProperty });
  
    return {
      dependentKeys: [onProperty],
      validate(subject) {
        if (!get(subject, onProperty)) {
          return error;
        }
      }
    };
  });
  // END-SNIPPET
  