Function promisify

resources/benchmark.js:7–18

(fn)

var Benchmark = require('benchmark');

function promisify(fn) {
  return function () {
    return new Promise((resolve, reject) =>
      fn.apply(
        this,
        Array.prototype.slice
          .call(arguments)
          .concat((err, out) => (err ? reject(err) : resolve(out)))
      )
    );
  };
}

var exec = promisify(child_process.exec);
var readdir = promisify(fs.readdir);