node/test/parallel/test-fs-promises-writefile-with-fd.js
Rich Trott f593f9e9ef test: adjust comments for upcoming lint rule
Enforce `//` for multiline comments. Some tests mixed and matched, and
at least one did so in a (to me) surprising way.

PR-URL: https://github.com/nodejs/node/pull/35485
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
2020-10-07 04:36:02 -07:00

37 lines
1013 B
JavaScript

'use strict';
// This test makes sure that `writeFile()` always writes from the current
// position of the file, instead of truncating the file.
const common = require('../common');
const assert = require('assert');
const path = require('path');
const { readFileSync } = require('fs');
const { open } = require('fs').promises;
const tmpdir = require('../common/tmpdir');
tmpdir.refresh();
const fn = path.join(tmpdir.path, 'test.txt');
async function writeFileTest() {
const handle = await open(fn, 'w');
/* Write only five bytes, so that the position moves to five. */
const buf = Buffer.from('Hello');
const { bytesWritten } = await handle.write(buf, 0, 5, null);
assert.strictEqual(bytesWritten, 5);
/* Write some more with writeFile(). */
await handle.writeFile('World');
/* New content should be written at position five, instead of zero. */
assert.deepStrictEqual(readFileSync(fn).toString(), 'HelloWorld');
await handle.close();
}
writeFileTest()
.then(common.mustCall());