code: function resolveAsync(p, base, root) {
    if (!path.isAbsolute(p)) {
      return new Promise(function(r, j) {
        resolve(forceRelative(p), {
          basedir: path.resolve(root, base)
        }, function(err, res) {
          if (err) {
            j(err);
          } else {
            r(res);
          }
        });
      });
  
    } else {
  
      return Promise.resolve(p);
    }
  }
docs: Resolve path the same way ans postcss-import
  
  @return {Promise}