nodejs/test/parallel/test-fs-promises-readfile-w...

36 lines
1005 B
JavaScript

'use strict';
/*
* This test makes sure that `readFile()` always reads from the current
* position of the file, instead of reading from the beginning of the file.
*/
const common = require('../common');
const assert = require('assert');
const path = require('path');
const { writeFileSync } = require('fs');
const { open } = require('fs').promises;
const tmpdir = require('../common/tmpdir');
tmpdir.refresh();
const fn = path.join(tmpdir.path, 'test.txt');
writeFileSync(fn, 'Hello World');
async function readFileTest() {
const handle = await open(fn, 'r');
/* Read only five bytes, so that the position moves to five. */
const buf = Buffer.alloc(5);
const { bytesRead } = await handle.read(buf, 0, 5, null);
assert.strictEqual(bytesRead, 5);
assert.deepStrictEqual(buf.toString(), 'Hello');
/* readFile() should read from position five, instead of zero. */
assert.deepStrictEqual((await handle.readFile()).toString(), ' World');
}
readFileTest()
.then(common.mustCall());