vitest 如何 spyOn fs?

Question

import * as fs from 'fs'
const path = './a.log'
function log(message){
    fs.appendFile(path,message,(err)=>{})
}

import fs from 'fs'
test('log',()=>{
 const spy = vi.spyOn(fs,'appendFile').mockImplementation((...args)=>{})
 log()
 expect(spy).toHaveBeenCalledTimes(1);
})

但是这个好像报错了..