spy and spyOnObject

spy.js

function spy(fn, prot = fn.prototype) {
  function proxy() {
    const args = Array.prototype.slice.call(arguments);
    proxy.calls.push(args);
    proxy.called = true;
    return fn.apply(this, args);
  }

  proxy.prototype = prot;
  proxy.calls = [];
  proxy.called = false;

  return proxy;
}


function spyOnObject(o) {
    const o2 = {};
    for (let k in o) {
        const v = o[k];
        o2[k] = (typeof v === 'function') ? spy(v, o.prototype) : v;
    }
    return o2;
}

/// EXAMPLE USAGES:

/*
function soma(a, b) { return a + b; }
const soma2 = spy(soma);
console.log( soma2(2, 3) );
console.log( soma2(25, 11) );
*/

/*
const o = {
    count: 0,
    soma: function(a, b) { return a + b; },
    add1: function() { return ++this.count; }
};
const o2 = spyOnObject(o);
o2.soma(2, 3);
o2.add1();
o2.add1();
*/