code: function resolveFile (dir, file) {
    return new Promise((resolve, reject) => {
      resolver.resolve({}, dir, file, (err, result) => {
        if (err) reject(err)
        else resolve(result)
      })
    })
  }
docs: Async resolve a files path using nodes module resolution.
  
  @param {string} dir - the directory to look in.
  @param {string} file - the file to find.
  @return {Promise<string>}