node/test/parallel/test-fs-options-immutable.js

'use strict';
const common = require('../common');

// These tests make sure that the `options` object passed to these functions are
// never altered.
//
// Refer: https://github.com/nodejs/node/issues/7655

const fs = require('fs');

const options = common.mustNotMutateObjectDeep({});
const tmpdir = require('../common/tmpdir');
tmpdir.refresh();

fs.readFile(__filename, options, common.mustSucceed());
fs.readFileSync(__filename, options);

fs.readdir(__dirname, options, common.mustSucceed());
fs.readdirSync(__dirname, options);

if (common.canCreateSymLink()) {
  const sourceFile = tmpdir.resolve('test-readlink');
  const linkFile = tmpdir.resolve('test-readlink-link');

  fs.writeFileSync(sourceFile, '');
  fs.symlinkSync(sourceFile, linkFile);

  fs.readlink(linkFile, options, common.mustSucceed());
  fs.readlinkSync(linkFile, options);
}

{
  const fileName = tmpdir.resolve('writeFile');
  fs.writeFileSync(fileName, 'ABCD', options);
  fs.writeFile(fileName, 'ABCD', options, common.mustSucceed());
}

{
  const fileName = tmpdir.resolve('appendFile');
  fs.appendFileSync(fileName, 'ABCD', options);
  fs.appendFile(fileName, 'ABCD', options, common.mustSucceed());
}

if (!common.isIBMi) { // IBMi does not support fs.watch()
  const watch = fs.watch(__filename, options, common.mustNotCall());
  watch.close();
}

{
  fs.watchFile(__filename, options, common.mustNotCall());
  fs.unwatchFile(__filename);
}

{
  fs.realpathSync(__filename, options);
  fs.realpath(__filename, options, common.mustSucceed());
}

{
  const tempFileName = tmpdir.resolve('mkdtemp-');
  fs.mkdtempSync(tempFileName, options);
  fs.mkdtemp(tempFileName, options, common.mustSucceed());
}

{
  const fileName = tmpdir.resolve('streams');
  fs.WriteStream(fileName, options).once('open', common.mustCall(() => {
    fs.ReadStream(fileName, options).destroy();
  })).end();
}