1'use strict';
2
3// This test makes sure that `writeFile()` always writes from the current
4// position of the file, instead of truncating the file.
5
6const common = require('../common');
7const assert = require('assert');
8const path = require('path');
9const { readFileSync } = require('fs');
10const { open } = require('fs').promises;
11
12const tmpdir = require('../common/tmpdir');
13tmpdir.refresh();
14
15const fn = path.join(tmpdir.path, 'test.txt');
16
17async function writeFileTest() {
18  const handle = await open(fn, 'w');
19
20  /* Write only five bytes, so that the position moves to five. */
21  const buf = Buffer.from('Hello');
22  const { bytesWritten } = await handle.write(buf, 0, 5, null);
23  assert.strictEqual(bytesWritten, 5);
24
25  /* Write some more with writeFile(). */
26  await handle.writeFile('World');
27
28  /* New content should be written at position five, instead of zero. */
29  assert.strictEqual(readFileSync(fn).toString(), 'HelloWorld');
30
31  await handle.close();
32}
33
34
35writeFileTest()
36  .then(common.mustCall());
37