How to use the browserify-zlib.gunzipSync function in browserify-zlib

export function loadTests(tag) {
    let filename = 'testcases/' + tag + ".json.gz";
    if (Cache[filename] == null) {
        console.log("loading:", filename);
        Cache[filename] = JSON.parse(zlib.gunzipSync(new Buffer(data[filename], "base64")).toString());
    }
    return Cache[filename];
}
export function loadData(filename) {

export function loadTests(tag) {
    let filename = path.resolve(__dirname, '../testcases', tag + '.json.gz');
    return JSON.parse(zlib.gunzipSync(fs.readFileSync(filename)).toString());
}
export function loadData(filename) {

export function loadTests(tag: string): any {
   let filename = path.resolve(__dirname, '../testcases', tag + '.json.gz');
   return JSON.parse(zlib.gunzipSync(fs.readFileSync(filename)).toString());
}

export var decode = (encoded:string) : Object[] => {
  var decoded = new Buffer(encoded, 'base64');
  var uncompressedBuffer :Buffer;
  try {
    uncompressedBuffer = zlib.gunzipSync(decoded);
  } catch (e) {
    log.debug('gzip failed, assuming uncompressed messages');
    uncompressedBuffer = decoded;
  }
  var json = uncompressedBuffer.toString();
  return JSON.parse(json);
};