dataobject.html

<template name="index">
  Test 1: Non-enumerable property by prototype in a Handlebars expression.
  <br>Expected: «Hello World by prototype»
  <br>Actual: «{{hello}}»
  
  <hr>
  
  Test 2: Instance property in a Handlebars expression.
  <br>Expected: «Hello World by field»
  <br>Actual: «{{directHello}}»

  <hr>

  Test 3: Same non-enumerable property in a Handlebars helper.
  <br>Expected: «Hello World by prototype»
  <br>Actual: «{{helperHello}}»
</template>

dataobject.js

if (Meteor.isServer) return

function Example() { this.directHello = "Hello World by field" }

Object.defineProperty(Example.prototype, 'hello', {
  value: "Hello World by prototype"
})

Router.map(function() {
  this.route('index', {path: '/', data: function() { return new Example }})
})

Template.index.helperHello = function() { return (new Example).hello }

Result

Test 1: Non-enumerable property by prototype in a Handlebars expression. 
Expected: «Hello World by prototype» 
Actual: «»
------------------------------------------------------------------------
Test 2: Instance property in a Handlebars expression. 
Expected: «Hello World by field» 
Actual: «Hello World by field»
------------------------------------------------------------------------
Test 3: Same non-enumerable property in a Handlebars helper. 
Expected: «Hello World by prototype» 
Actual: «Hello World by prototype»