callback转Promise

环境：  nodejs - v6.2.0

const fs = require('fs');

let Promise = require('bluebird');

let readSync = function(filePath) {
  return new Promise(function(resolve, reject) {
      fs.unlink(filePath, (err) => {
        if(err) return reject(err);
        return resolve();
      })
  })
}

readSync('log').then(function(data) {
  console.log('OKKKKK');
}).catch(function(err) {
  console.log(err || 'errror!!');
})