Running a global test setup before each test in Jest - unit-testing

Question

I'm trying to have a test setup function executed before each single test in my Jest test suite. I know that I can use beforeEach to accomplish this within a single test file, but I want to do it globally for all my test files without having to explicitly modify each single file.
I looked into the jest configuration file, and noticed a couple of configs that thought could have worked: globalSetup and setupFiles, but they seem to be run only once (at the very beginning of the test run). Like I said, I need it to be run before "each" it block in my test files.
Is this possible?

Answer 1

You could use setupFilesAfterEnv (which replaces setupTestFrameworkScriptFile, deprecated from jest version 24.x) which will run before each test
// package.json
{
// ...
"jest": {
"setupFilesAfterEnv": ["<rootDir>/setupTests.js"]
}
}
And in setupTests.js, you can directly write:
global.beforeEach(() => {
...
});
global.afterEach(() => {
...
});

Answer 2

Just as a follow-up to the answer from #zzz, the more recent documentation on Configuring Jest notes:
Note: setupTestFrameworkScriptFile is deprecated in favor of setupFilesAfterEnv.
So now, your file should look like this:
// package.json
{
// ...
"jest": {
"setupFilesAfterEnv": [
"<rootDir>/setupTests.js"
]
}
}

Answer 3

setupFilesAfterEnv configuration is the way to go, and yes you can use beforeEach in that file and it will run in every test across all the suit.
// jest.config.js
module.exports = {
setupFilesAfterEnv: ['<rootDir>/tests/setupTests.ts']
}
// tests/setupTests.ts
beforeEach(() => {
console.log('before each')
})
afterEach(() => {
console.log('after each')
})
Try it out!