A simple wrapper function in JavaScript - more fun with closures

gistfile1.js

var truth = function() { return true; };
var relativeTruth = function() { return false; };

var assert = function(func) {
  return func() == true;
};

var wrapper = function(func) {
  
  // perform setup work here
  // executed once when wrapper() is executed
  console.info('the wrap is set');
  
  // The result of calling wrapper() is to return an anonymous
  // function that has wrapped the original function in a closure
  return function() {
    // perform wrapped work here
    // executed every time the wrapped function is called
    console.info('wrap, wrap, wrap, the boys are marching');
    
    // now call the original method
    var args = Array.prototype.slice.call(arguments)[0];
    return func(args);
  }
};

assert = wrapper(assert); // the wrap is set

console.info(assert(truth)); // 'wrap wrap wrap the boys are marching', true
console.info(assert(relativeTruth)) // 'wrap wrap wrap the boys are marching', false

oh and by the way this is a better wrapper:

var spy = function(func) {
  return function() {
        var args = [].splice.call(arguments, 0);
        console.log('function (', args, ')');
    return func.apply(this, args);
  }
};