Event is missing in in setup file under testEnvironment=node, ReferenceError: Event is not defined, Jest 27 #11528

[jayphelps]

🐛 Bug Report

The globals Event and EventTarget are missing in any setup file under testEnvironment=node (the default)

ReferenceError: Event is not defined

#11528 actually caught this but it was closed because presumably it was not known to that maintainer that Node v15.4 got native support for Event and EventTarget.

To Reproduce

Steps to reproduce the behavior:

# 15.4 or higher
nvm use node 15.4
# Optionally confirm that node does in fact have Event natively now
node -e "console.log(Event)"

jest.config.js

module.exports = {
  setupFiles: ['./setupJest.js'],
};

setupJest.js

// use it somehow
Event;
// ReferenceError: Event is not defined

Expected behavior

Event and EventTarget are available globally.

envinfo

System:
    OS: macOS 10.15.6
    CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  Binaries:
    Node: 15.7.0 - ~/.nvm/versions/node/v15.7.0/bin/node
    Yarn: 1.22.10 - ~/.nvm/versions/node/v15.0.1/bin/yarn
    npm: 7.4.3 - ~/.nvm/versions/node/v15.7.0/bin/npm

[Smrtnyk]

Node 15.7 is experimental and not an lts
Do you have issues with node 14 or node 16?

[jayphelps]

@Smrtnyk Unfortunately, yes. Though it's important to note that node 14 does not support Event/EventTarget so it not working there is expected. 15.4 is the minimum that supports Event and EventTarget, and the issue is reproducible from that version and beyond, including node 16.6.1 (latest stable.) I just happened to be using 15.7 but had confirmed that it was not 15.7 specific.

Here's a demo: https://github.com/jayphelps/jest-event-demo

[jayphelps]

If it's helpful, I did a little bit of digging. I'm not familiar with the jest codebase, but I imagine based on what I can see that it likely creates a new global context and has a hardcoded listed of exposed globals, and Event and EventTarget are just not among them yet because no one has brought it up.

Edit: I have confirmed this is the case. I'll submit a PR to add them. PR available: #11727

https://github.com/facebook/jest/blob/bc50e7f360ab1845abbaa0b3ad788caead0d3174/packages/jest-environment-node/src/index.ts#L34-L68

[Smrtnyk]

Makes sense. I see you filed a PR. Have you tried locally with your fix to see if it fixes your issues?

[jayphelps]

@Smrtnyk indeed I have. Works great.

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