[Bug]: Jest, jsdom and maybe ts-jest trouble with Buffer being an instance of Uint8Array

[lemoustachiste]

Version

29.6.1

Steps to reproduce

1. clone the repo: https://github.com/lemoustachiste/repro-jest-buffer-uint8array
2. npm install
3. npm test # this shows the tests failing
4. (npm run test:only-one) # this runs only one test to show that it works with only one file
5. (npm run node:compare) # this runs a node script to show that a Buffer should be an instanceof Uint8Array

Expected behavior

a Buffer should be an instance of Uint8Array when running multiple tests

Actual behavior

a Buffer is not an instance of Uint8Array when running multiple tests

Additional context

If only one test file is run it works (but not in watch mode).

If 2 files (accessing Uint8Array) are run it fails.

If I remove jsdom as test env, it works (but I need it in my origin repo)

If I remove ts-jest as a transformer, it sometimes work, but sometimes not (seems to be inconsistent with cache). But I need ts-jest in my origin repo.

A similar issue was reported here: #4422, however while it solves the general problem, the described issue persists.

Environment

System:
    OS: macOS 13.5
    CPU: (8) x64 Intel(R) Core(TM) i5-1038NG7 CPU @ 2.00GHz
  Binaries:
    Node: 16.20.0 - ~/.nvm/versions/node/v16.20.0/bin/node
    Yarn: 1.22.18 - /usr/local/bin/yarn
    npm: 9.8.0 - ~/.nvm/versions/node/v16.20.0/bin/npm
  npmPackages:
    jest: ^29.6.1 => 29.6.1

[mrazauskas]

Did you try using jest-light-runner for those specific tests which need instanceof? Reference: #2549 (comment)

[SimenB]

Duplicate of above linked issue

[lemoustachiste]

Thanks for the support.

So my goal is to eliminate tech-debt from my project, but adding jest light runner, while it solves my js repro, feels like heavily accepting new one.

My main problem being typescript support: nicolo-ribaudo/jest-light-runner#53.

Isn't there a better solution? Uint8Array support works when only one test runs, but not multiple. It seems like a problem with jest, but having to setup convoluted scaffolding just to run tests feels like a code smell.

[SimenB]

It's #2549 as mentioned. That issue contains a bunch of different workarounds.
Unfortunately, cross realm instanceof is a hard problem to solve.

[lemoustachiste]

I solved it by removing jsdom as the default environment and using it on a per test basis

[github-actions]

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