Function pad

test/unit/static/js/mocha.js:2027–2030

* Pad the given `str` to `len`. * * @param {String} str * @param {String} len * @return {String} * @api private

(str, len)

 */

function pad(str, len) {
  str = String(str);
  return Array(len - str.length + 1).join(' ') + str;
}

/**
 * Return a character diff for `err`.