Javascript Jest automock失败：类型错误：fs.readdirSync不是函数

我正在尝试生成“fs”模块的自动模拟，然后对其进行扩展，但我的实现不起作用：

// /home/user/cp/projectName/__mocks__/fs.js

const fs = jest.createMockFromModule('fs');

function readdirSync(fileName) {
  console.log(`The file name passed to this fake fs.readdirSync method is: ${fileName}`);

  return 'return value from fake fs.readdirSync';
}

function specialMethod() {
  return 'returned from the special method';
}

fs.readdirSync = readdirSync;
fs.specialMethod = specialMethod;

exports = fs;

上述

\uuuu mocks\uuuu

文件夹是

节点模块

文件夹的同级

运行测试文件似乎忽略了上述模拟模块：

// /home/user/cp/projectName/src/captureCallData/__tests__/unit.test.ts

/* eslint-disable no-undef */
jest.mock('fs');
const fs = require('fs');

test('test fs.specialMethod', () => {
  const result = fs.specialMethod();
});

function useFsInternally(fakeFileName: string) {
  return fs.readdirSync(fakeFileName);
}

test('test mocking functionality', () => {
  const result: string = useFsInternally('testInput');

  expect(result).toStrictEqual('wrong value');
});

也尝试过

• import

  和

  export

  语法，而不是

  require（）

  。在这种情况下，实际的fs模块似乎要导入，而不是模拟模块：

---

exports

是初始等于

模块的局部变量。exports

包含对导出对象的引用。它应该是变异的，而不是重新分配的

exports=fs

仅替换局部变量的值，不影响导出的值

应该是

module.exports = fs;

或

"dependencies": {
    "typescript": "^3.9.7"
  },
  "devDependencies": {
    "@types/jest": "^26.0.9",
    "jest": "^26.2.2",
    "ts-jest": "^26.1.4"
  }

    src/captureCallData/__tests__/unit.test.ts:12:21 - error TS2339: Property 'specialMethod' does not exist on type 'typeof import("fs")'.

    12   const result = fs.specialMethod();
                           ~~~~~~~~~~~~~
    src/captureCallData/__tests__/unit.test.ts:20:9 - error TS2322: Type 'string[]' is not assignable to type 'string'.

    20   const result: string = useFsInternally('testInput');
               ~~~~~~

module.exports = fs;

Object.assign(exports, fs);