How to mock file system with memfs in NodeJS - node.js

Question

I want to test the following function with the memfs package
import fs from 'fs-extra'
import path from 'path'
async function ensureParent(filepath: string) {
const absolutePath = path.resolve(filepath)
const parentDir = path.dirname(absolutePath)
const exists = await fs.pathExists(parentDir)
return exists
}
export default {
ensureParent,
}
To test it with an in-memory file system I have at the root of the project, the following __mocks__/fs.ts file
import { fs } from 'memfs'
export default fs
and the following __mocks__/fs/promises.ts file
import { fs } from 'memfs'
export default fs.promises
Here is the test file file.test.ts
import { describe, it, expect, vi, beforeAll, beforeEach } from 'vitest'
import { vol } from 'memfs'
import f from '../file'
vi.mock('fs')
vi.mock('fs/promises')
const fileSystem = {
'./exists/shiman.txt': 'Hello shiman',
}
beforeAll(() => {
vol.fromJSON(fileSystem, '/tmp')
})
beforeEach(() => {
vol.reset()
})
describe.concurrent('file utils', () => {
it('ensure a directory exists', async () => {
expect(await f.ensureParent('/tmp/exists/shiman.txt')).toBe(true)
})
})
However, the test keeps failing, and I realized that, although the mock is taken into account, the in-memory file system is not because await fs.readdir('/', (err, data) => console.log(err, data)) logs the content of / in my machine.
Have I done something wrong?