Allow a way to force reset the DOM between test runs in the same file

[gxxcastillo]

Allow a way to force reset the DOM between test runs in the same file

[AriPerkkio]

I've tried going through and copying the code that vitest uses to clear the dom between test files but it's not trivial.

Vitest doesn't do any DOM specific clean ups between test files. By default each test file is isolated using node:worker_threads or node:child_process depending on selected pool. Isolation (clean DOM) between tests is provided by terminating previous worker/thread and spinning up a new one.

If you are using testing-library packages, you should use their cleanup() method in Vitest's afterEach() hook. https://testing-library.com/docs/react-testing-library/api#cleanup
Otherwise you'll need to provide your own cleanup methods manually, for example: https://github.com/AriPerkkio/aria-live-capture/blob/master/test/setup.ts.

[sheremet-va]

As @AriPerkkio already said, we already provide isolation for every test file. This is the intended design of Vitest. If there was a way to isolate global scope in test functions, we would've already used it.

Please follow @AriPerkkio advice on how to cleanup DOM in your Vitest tests, there is nothing more Vitest can do on our side.

[gxxcastillo]

Hi @AriPerkkio, thanks for helping me better understand how each test file is isolated from the other.

I'm currently using the cleanup method from the react-testing-library but it only cleans up the react tree. Specifically from the docs:

Unmounts React trees that were mounted with render.

Is there no way to isolate each test?

[gxxcastillo]

While researching a solution, i found that playwright seems to offer isolation for each test. Though they seem to be leveraging browser context instead of threads and forks:

https://playwright.dev/docs/writing-tests#test-isolation

[sheremet-va]

Playwright opens a separate isolate page for every test, the test functions themselves are not isolated. Since Vitest just runs test functions, we cannot provide the same type of isolation that Playwright has.

[gxxcastillo]

If a new instance of jsdom/happy-dom/etc... were instantiated on every test case, would that solve the issue?

[sheremet-va]

If a new instance of jsdom/happy-dom/etc... were instantiated on every test case, would that solve the issue?

No, the global scope is the same.