private-function-tests.js

// During build, delete everything between start and end tags, keeping things safely scoped
// This exists for Grunt, and seems relatively easy to port to Gulp.
// https://github.com/philipwalton/grunt-strip-code/

(function hasPrivateFunctions (window) {
  
  this.isPublicFunction = isPublicFunction;
  
  function isPublicFunction () {
    return 'I am a public function'; 
  }
  
  function isPrivateFunction () {
    return 'I am a private function';
  }
  
  /* start-testing-code-section */
  
    window.testableApiObject.isPrivateFunction = isPrivateFunction;
  
  /* end-testing-code-section */
  
})(window);
  
window.isPublicFunction() // 'I am a public function'

window.isPrivateFunction() // TypeError, this is good

window.testableApiObject.isPrivateFunction() // 'I am a private function'