如何在我的 Jest 配置中设置时区? [英] How do I set a timezone in my Jest config?

问题描述

✗ npx jest --version24.5.0

有一组对时区敏感的笑话测试.我们通常使用 npm 脚本运行它们:"jest": "TZ=utc jest"

将 TZ 设置为 utc 后，我在快照中得到如下值:

modificationDate="2019-01-08T00:00:00.000Z"

没有它我得到:

modificationDate="2019-01-08T08:00:00.000Z"

有没有办法在我的 jest 配置中设置它，这样我就可以在命令行中运行 npx jest 而无需通过 NPM 脚本?配置文档关于这个.

我尝试将这两个添加到我的 jest.config.js.没有一个工作:

 TZ: 'utc',全局变量:{TZ: 'UTC',},

当然，解决这个问题似乎微不足道，但我很惊讶 Jest 没有办法为测试配置它.

解决方案

这在节点 17.0.1 之前的 Windows 上不起作用 - 请参阅 https://github.com/nodejs/node/issues/4230

---

process.env.TZ = 'UTC'; 的问题是，如果在此行之前运行并使用 Date，该值将被缓存在 <代码>日期.因此process.env 一般不适合设置时区.请参阅https://github.com/nodejs/node/issues/3449>

所以更好的方法是使用实​​际的 env 变量，但对于测试，这将起作用:

1.将此添加到您的 package.json

 玩笑":{...//根据你的路径，它也可以是 './global-setup.js'globalSetup":../global-setup.js"}}

2.把这个文件放在 package.json 之外作为 global-setup.js

module.exports = async() =>{process.env.TZ = 'UTC';};

3.可选:添加确保 UTC 执行的测试

describe('Timezones', () => {it('应该总是UTC', () => {期望(新日期().getTimezoneOffset()).toBe(0)；});});

普通的setupFiles 对我来说不起作用，因为它们运行得太晚了(笑话:^23.5.0).因此，强制使用 globalSetup 文件.

✗ npx jest --version
24.5.0

Got a set of jest tests that are timezone sensitive. We typically run them with an npm script: "jest": "TZ=utc jest"

With the TZ set to utc I get values like this in snapshots:

modificationDate="2019-01-08T00:00:00.000Z" 

Without it I get:

modificationDate="2019-01-08T08:00:00.000Z"

Is there a way to set that in my jest config so I can run npx jest at the command line without having to go through the NPM script? There's nothing in config docs about this.

I tried adding these two to my jest.config.js. Neither one worked:

  TZ: 'utc',

  globals: {
    TZ: 'utc',
  },

Sure, it seems trivial to work around but I'm surprised Jest doesn't have a way to configure this for tests.

解决方案

This does not work on windows prior to node 17.0.1 - see https://github.com/nodejs/node/issues/4230

---

The problem with process.env.TZ = 'UTC'; is, that if something runs before this line and uses Date, the value will be cached in Date. Therefore process.env is in general not suitable for setting the timezone. See https://github.com/nodejs/node/issues/3449

So a better way is to use an actual env variable, but for tests this will work:

1. Add this to your package.json

  "jest": {
     ...
     // depending on your paths it can also be './global-setup.js' 
    "globalSetup": "../global-setup.js"
  }
}

2. Put this file besides package.json as global-setup.js

module.exports = async () => {
    process.env.TZ = 'UTC';
};

3. Optional: Add a test that ensures UTC execution

describe('Timezones', () => {
    it('should always be UTC', () => {
        expect(new Date().getTimezoneOffset()).toBe(0);
    });
});

The normal setupFiles did not work for me, since they run too late (jest: ^23.5.0). So it is mandatory to use the globalSetup file.

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