node/test/parallel/test-vfs-fs-createWriteStream.js
Matteo Collina 569369f927
vfs: dispatch fs/promises to mounted VFS instances
Add mount/unmount lifecycle on `VirtualFileSystem`, a handler registry
that fs.js and fs/promises.js consult via `vfsState.handlers`, and a
router that maps absolute paths to the VFS that owns them. When a VFS
is mounted, the public `fs.*` and `fs/promises` APIs (including
streams, `fs.watch`, and `opendir`) dispatch to the provider for paths
under the mount point, and fall through to the real filesystem
otherwise. Includes per-method dispatch tests, error-path coverage,
multi-mount routing tests, and router unit tests.

Ref: https://github.com/nodejs/node/pull/63115

Signed-off-by: Matteo Collina <hello@matteocollina.com>
PR-URL: https://github.com/nodejs/node/pull/63537
Refs: https://github.com/nodejs/node/pull/63115
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
2026-05-29 17:57:34 +00:00

47 lines
1.4 KiB
JavaScript

// Flags: --experimental-vfs
'use strict';
// fs.createWriteStream dispatches through VFS, exposes a `path` property and
// emits an 'open' event with the bitmask-encoded virtual fd.
const common = require('../common');
const assert = require('assert');
const fs = require('fs');
const path = require('path');
const vfs = require('node:vfs');
const baseMountPoint = path.resolve(
'/tmp/vfs-createWriteStream-' + process.pid,
);
let counter = 0;
function mounted() {
const mountPoint = baseMountPoint + '-' + (counter++);
const myVfs = vfs.create();
myVfs.mkdirSync('/src', { recursive: true });
myVfs.mount(mountPoint);
return { myVfs, mountPoint };
}
// Basic write
{
const { myVfs, mountPoint } = mounted();
const target = path.join(mountPoint, 'src/sw.txt');
const stream = fs.createWriteStream(target);
stream.write('stream ');
stream.end('data', common.mustCall(() => {
assert.strictEqual(fs.readFileSync(target, 'utf8'), 'stream data');
myVfs.unmount();
}));
}
// Path getter + 'open' event with a VFS fd
{
const { myVfs, mountPoint } = mounted();
const target = path.join(mountPoint, 'src/ws-open.txt');
const stream = fs.createWriteStream(target);
assert.strictEqual(stream.path, target);
stream.on('open', common.mustCall((fd) => {
assert.notStrictEqual(fd & 0x40000000, 0);
}));
stream.end('done', common.mustCall(() => myVfs.unmount()));
}