node/test/parallel/test-fs-write-file-sync.js

var common = require('../common');
var assert = require('assert');
var path = require('path');
var fs = require('fs');
var isWindows = process.platform === 'win32';
var openCount = 0;
var mode;
var content;

// Need to hijack fs.open/close to make sure that things
// get closed once they're opened.
fs._openSync = fs.openSync;
fs.openSync = openSync;
fs._closeSync = fs.closeSync;
fs.closeSync = closeSync;

// Reset the umask for testing
var mask = process.umask(0000);

// On Windows chmod is only able to manipulate read-only bit. Test if creating
// the file in read-only mode works.
if (isWindows) {
  mode = 0444;
} else {
  mode = 0755;
}

// Test writeFileSync
var file1 = path.join(common.tmpDir, 'testWriteFileSync.txt');
removeFile(file1);

fs.writeFileSync(file1, '123', {mode: mode});

content = fs.readFileSync(file1, {encoding: 'utf8'});
assert.equal('123', content);

assert.equal(mode, fs.statSync(file1).mode & 0777);

removeFile(file1);

// Test appendFileSync
var file2 = path.join(common.tmpDir, 'testAppendFileSync.txt');
removeFile(file2);

fs.appendFileSync(file2, 'abc', {mode: mode});

content = fs.readFileSync(file2, {encoding: 'utf8'});
assert.equal('abc', content);

assert.equal(mode, fs.statSync(file2).mode & mode);

removeFile(file2);

// Verify that all opened files were closed.
assert.equal(0, openCount);

// Removes a file if it exists.
function removeFile(file) {
  try {
    if (isWindows)
      fs.chmodSync(file, 0666);
    fs.unlinkSync(file);
  } catch (err) {
    if (err && err.code !== 'ENOENT')
      throw err;
  }
}

function openSync() {
  openCount++;
  return fs._openSync.apply(fs, arguments);
}

function closeSync() {
  openCount--;
  return fs._closeSync.apply(fs, arguments);
}