获取 `TypeError: jest.fn 不是一个函数`

我正在尝试使用 Jest 创建以下单元测试。

jest.dontMock("pointsAwardingActions.js");
describe("points awarding actions", () => {
  describe("award points", () => {
    it("should dispatch begin ajax action", () => {
      var pointsAwardingActions = require("pointsAwardingActions.js");
      const mockedDispatch = jest.fn();
    });
  });
});

但运行后出现以下错误npm test.

类型错误：jest.fn 不是函数

这是我的一些部分package.json:

{
  "scripts": {
    "test": "jest"
  },
  "author": "alayor",
  "license": "ISC",
  "jest": {
    "scriptPreprocessor": "<rootDir>/node_modules/babel-jest",
    "testFileExtensions": ["spec.js"],
    "moduleFileExtensions": ["js"],
    "collectCoverage": "true"
  },
  "dependencies": {
    "babel-cli": "6.8.0",
    "babel-core": "6.8.0",
    "babel-jest": "^6.0.1",
    "babel-loader": "6.2.4",
    "babel-plugin-react-display-name": "2.0.0",
    "babel-polyfill": "6.8.0",
    "babel-preset-es2015": "6.6.0",
    "babel-preset-react": "6.5.0",
    "babel-preset-react-hmre": "1.1.1",
    "expect": "1.19.0",
    "express": "4.13.4",
    "jest": "^0.1.40",
    "jest-cli": "^0.8.1",
    ...
  }
}

我收到该错误的原因可能是什么？

The jest object https://facebook.github.io/jest/docs/en/jest-object.html自动在每个测试文件的范围内，因此无需显式导入它。如果您确实想导入jest直接对象，你想导入 jest-mock 模块，而不是 jest-cli 模块，通过：

// Not necessary inside a Jest test file
import jest from 'jest-mock';

const mock = jest.fn();