code: function stop() {
    return new Promise((resolve) => {
      if (child && child.kill) {
        debug('stopping test server');
        child.kill('SIGTERM');
        process.removeListener('exit', stop);
        child = null;
        debug('stopped test server');
      }
  
      resolve();
    });
  }
docs: Stops the test server
  @returns {Promise}