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我尝试使用 jest 来模拟导入的函数，但出现此错误，TypeError: Assignment to constant variable.或者TypeError: Cannot assign to read only property 'sum' of object '[object Module]'，我希望获得在本测试中模拟的返回值

尝试1

import { jest } from '@jest/globals'
import * as util from "./util.js"

it("TypeError: Cannot assign to read only property 'sum' of object '[object Module]'", () => {
  jest.spyOn(util, "sum").mockImplementation(() => { return 2 })
  
  expect(sum(1, 2)).toBe(2);
})

尝试2

import { jest } from '@jest/globals'
import { sum } from './util.js'

it("TypeError: Cannot assign to read only property …