When should I use setupFiles rather than setupFilesAfterEnv? - jestjs

Question

I see that there are two config options in jest for having some code running before each tests : setupFiles and setupFilesAfterEnv. It seems to me that setupFilesAfterEnv gives more flexibility (I can use jest, beforeEach and so on ...), so I don't understand in what context setupFiles would be more useful. Can someone provide an example where you need to use setupFiles rather than setupFilesAfterEnv ?
Documentation : https://jestjs.io/docs/en/configuration#setupfiles-array

Answer 1

We can see what different between setupFiles and setupFilesAfterEnv from the documentation.
The most important difference will probably be when it is run.
setupFiles will be executed
before the test framework is installed in the environment.
setupFilesAfterEnv will be executed
after the test framework has been installed in the environment.
That's why the name has AfterEnv.
I actually use both of them in my actual project.
In my case, I use the setupFiles to set up fro .env values and use the setupFilesAfterEnv to set up jest configuration like jest.setTimeout(70000)
>> In my case >>>>>>>>>>>>>>>>>>>>>>>
jest.config.js
setupFiles: ['<rootDir>/tests/settings/env-setup.ts'],
setupFilesAfterEnv: ['<rootDir>/testSetupFile.js'],
env-setup.ts
import dotenv from 'dotenv';
import path from 'path';
console.log(`============ env-setup Loaded ===========`);
dotenv.config({ path: path.resolve(process.cwd(), 'tests', 'settings', '.test.env') });
testSetupFile.ts
// Some of the `jest` tests are very slow and cause
// timeouts on bitbucket pipeline
console.log(`============ testSetupFile Loaded ===========`);
jest.setTimeout(70000);