得到'TypeError:jest.fn不是函数`

Question

我正在尝试使用创建以下单元测试jest.

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();
    });
  });
});

但运行后我收到以下错误npm test.

TypeError: jest.fn is not a function

这是我的一部分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",
    ...
  }
}

可能是我得到那个错误的原因.

Answer 1

该玩笑的对象会自动在每个测试文件内的范围,所以没有必要明确地导入.如果您确实想直接导入jest对象,则需要通过以下方式导入jest-mock模块,而不是jest-cli模块:

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

const mock = jest.fn();

Answer 2

有点奇怪，文档没有提到jestnot require('jest');but require('jest-mock')，以下代码应该适用于 v22：

const jest = require('jest-mock');
const spy = jest.fn();