'use strict'; const common = require('../common'); const assert = require('assert'); const path = require('path'); const Buffer = require('buffer').Buffer; const fs = require('fs'); const filename = path.join(common.tmpDir, 'write.txt'); const expected = Buffer.from('hello'); common.refreshTmpDir(); fs.open(filename, 'w', 0o644, common.mustCall(function(err, fd) { if (err) throw err; fs.write(fd, expected, 0, expected.length, null, common.mustCall(function(err, written) { if (err) throw err; assert.equal(expected.length, written); fs.closeSync(fd); var found = fs.readFileSync(filename, 'utf8'); assert.deepStrictEqual(expected.toString(), found); fs.unlinkSync(filename); })); }));