async do_test(cmd, args, env, cwd, keepalive) {
    const res = spawnSync(cmd, args, {
      stdio: "inherit",
      env,
      cwd,
    });
    if (res.status !== 0 && !keepalive) this.exit(res.status);
    return res;
  }
@param {string} cmd
@param {string[]} args
@param {*} env
@param {*} cwd
@param {boolean} keepalive
@returns {object}