fetch is undefined with experimentalVmThreads: true

[nstepien]

Describe the bug

Without experimentalVmThreads, our JSDOM tests can use Node's fetch implementation in our tests.
When experimentalVmThreads is enabled, the global fetch is missing.

Reproduction

vite.config.js:

import { defineConfig } from 'vite';

export default defineConfig({
  test: {
    experimentalVmThreads: true,
    environment: 'jsdom'
  }
});

test file:

import { test, expect } from 'vitest';

test('global fetch', () => {
  expect(globalThis.fetch).toBeDefined();
});

System Info

System:
    OS: Windows 10 10.0.22621
    CPU: (64) x64 AMD Ryzen Threadripper 3970X 32-Core Processor
    Memory: 23.16 GB / 31.88 GB
  Binaries:
    Node: 20.8.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.1.0 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Chromium (117.0.2045.43)
    Internet Explorer: 11.0.22621.1
  npmPackages:
    @vitejs/plugin-react: ^4.1.0 => 4.1.0
    @vitest/coverage-v8: ^0.34.5 => 0.34.5
    vite: ^4.4.9 => 4.4.9
    vitest: ^0.34.5 => 0.34.5

Used Package Manager

npm

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• Read the Contributing Guidelines.
• Read the docs.
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• The provided reproduction is a minimal reproducible example of the bug.

[sheremet-va]

JSDOM doesn't provide fetch on window object, so it's not there. VM mode is more strict and uses actual context instead of patching global variables, so you should have environment close to what you have in the browser.

I'm not against patching it by extending the context with fetch/Request/Response in https://github.com/vitest-dev/vitest/blob/main/packages/vitest/src/integrations/env/jsdom.ts

[nstepien]

Yes that'd be nice!
I wonder if there are additional web globals provided by Node that need to be patched in. 🤔