ember-cli-i18n-testing.js

import Stream from 'ember-cli-i18n/utils/stream';
import t from 'ember-cli-i18n/utils/t';
import Ember from 'ember';

// tHelper without the container and application dependencies, sigh...
function tHelper(params /*, hash, options, env */) {
  var path = params.shift();

  var stream = new Stream(function() {
    return t(path, params);
  });

  // bind any arguments that are Streams
  for (var i = 0, l = params.length; i < l; i++) {
    var param = params[i];
    if(param && param.isStream){
      param.subscribe(stream.notify, stream);
    }
  }

  if (path.isStream) {
    path.subscribe(stream.notify, stream);
  }

  return stream;
}

export function registerI18N() {
  // Yay, private APIs!
  Ember.HTMLBars._registerHelper('t', tHelper);
}

where do you put this code?

Yeah, I am wondering the same!