Jest beforeAll() share between multiple test files

问题

I have a Node.js project that I'm testing using Jest. I have several test files that have the same setup requirement. Previously, all these tests were in one file, so I just had a beforeAll(...) that performed the common setup. Now, with the tests split into multiple files, it seems like I have to copy/paste that beforeAll(...) code into each of the files. That seems inelegant - is there a better way to do this, ideally where I can just write my beforeAll(...)/setup logic once, and "require" it from multiple test files? Note that there are other tests in my test suite that don't require this setup functionality, so I don't want to make all my tests run this setup (just a particular subset of test files).

回答1:

If you're using Jest >=20, you might want to look into creating a custom jest-environment for the tests that require this common setup. This would be a module that extends either jest-environment-node or jest-environment-jsdom, and implements async setup(), async teardown(), and async runScript() to do this setup work.

You can then add a @jest-environment my-custom-env directive to those files that require this setup.

See the Jest config docs for testEnvironment for details on how to set this up; there's a simple example there.

回答2:

You can move your beforeAll logic into one file and reference it in jest.config.js setupFilesAfterEnv section:

module.exports = {
...
setupFilesAfterEnv: ['<rootDir>/testHelper.ts'],
...
}

https://jestjs.io/docs/en/configuration#setupfilesafterenv-array

回答3:

If you need a script to run before all your test files, you can use globalSetup

This option allows the use of a custom global setup module which exports an async function that is triggered once before all test suites.

in your jest.config.js

//jest.config.js
module.exports = {
  ...
  testTimeout: 20000,
  globalSetup: "./setup.js"
};

then create a file named setup.js

// setup.js
module.exports = async () => {
    
    console.log("I'll be called first before any test cases run");
    //add in what you need to do here

};

Docs

来源：https://stackoverflow.com/questions/47997652/jest-beforeall-share-between-multiple-test-files

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jestjs