为什么无法在测试代码中获取在globalSetup中设置的全局变量? [英] Why can't get the global variable which was set in globalSetup in test code?

问题描述

我使用Jest在节点中进行单元测试.
并且我使用了Jest中的新功能 globalSetup v22.
我已经在 globalSetup 中定义了全局变量.
但是我无法在测试代码中得到它.控制台日志未定义.
有任何疑问吗?
谢谢.

I use Jest to do unit test in node.
And I use the new feature globalSetup which come in Jest v22.
I have defined a global variable in globalSetup.
But I can't get it in the test code. Console log is undefined.
Anyone in this question?
Thanks.

最佳版本:22.0.0
节点版本:8.9.0
纱线版本:1.3.2
操作系统:mac High Sierra 10.13.2

Jest version: 22.0.0
node version: 8.9.0
yarn version: 1.3.2
OS: mac High Sierra 10.13.2

代码如下:

// package.json
{
  "jest": {
    "globalSetup": "<rootDir>/src/globalSetupTest.js"
  }
}

// globalSetupTest.js
module.exports = async function() {
  global.foo = 'foo';
  console.log(`global setup: ${global.foo}`);
};

// App.test.js
describe('APP test', () => {
  it('renders without crashing', () => {
    console.log({ foo: global.foo });
  });
});

// test result
yarn run v1.3.2
$ node scripts/test.js --env=node --colors
global setup: foo
 PASS  src/App.test.js
  APP test
    ✓ renders without crashing (5ms)

  console.log src/App.test.js:3
    { foo: undefined }

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        0.354s, estimated 1s
Ran all test suites.

推荐答案

Jest人自己提供了一个解决方案:

There's a solution offered from Jest people themselves: https://jestjs.io/docs/en/puppeteer.html. Note that if you're using CRA, this won't work out of the box (solution below), cause it currently doesn't support testEnvironment option for Jest.

无论如何:

• 在Jest配置文件中，您设置了指向全局设置，拆卸和测试环境脚本的路径
• 在全局设置脚本中，您创建一个浏览器并将其WSEndpoint写入文件中
• 在全局拆卸脚本中，您只需关闭浏览器
• 在testEnvironment脚本中，您从之前保存的文件中读取WSEndpoint，然后使用它连接到正在运行的浏览器-此后，通过使用全局变量，浏览器可用于您的测试中

如果您使用的是CRA，则可以对这些测试使用自定义设置，然后完全单独运行它们.而且，如果您要使用Puppeteer进行e2e测试，那么无论如何，这可能就是您想要做的.

If you're using CRA, you can use a custom setup for these tests and run them completely separately. And if you're using Puppeteer for e2e tests, this is probably what you want to do anyway.

您只需将另一个脚本添加到package.json:"test:e2e": "jest -c ./jest-e2e.config.js"并根据需要进行设置.现在，您将具有npm run test用于单元测试，而npm run test:e2e用于端到端测试.

You just add another script to your package.json: "test:e2e": "jest -c ./jest-e2e.config.js" and set it up as you want. Now you will have npm run test for unit tests and npm run test:e2e for end to end tests.

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