Undici MockAgent cannot intercept fetch request anymore

[Guymestef]

Describe the bug

Since the version 2.1.5, we cannot mock anymore our http calls with undici MockAgent due to the bug fix:
vitest:
Use fetch() implementation from happy-dom - by @capricorn86 in #6879 (3c56f)

Reproduction

import { MockAgent, setGlobalDispatcher } from 'undici';

describe('Test mock fetch with undici', () => {
    it('should success', async () => {
       
       const mockAgent = new MockAgent();
       mockAgent.disableNetConnect();
       setGlobalDispatcher(mockAgent);

        const apiMockPool = mockAgent.get('https://localhost');

       apiMockPool
         .intercept({ method: 'GET', path: '/api/v1/test' })
         .reply(200, { success: true })
         .persist();

       const result = await fetch('https://localhost/api/v1/test');
       expect(result).toBeDefined();
    });

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz
    Memory: 16.25 GB / 31.71 GB
  Binaries:
    Node: 23.2.0 - ~\bin\node-v23.2.0-win-x64\node.EXE
    Yarn: 4.5.0 - ~\bin\node-v23.2.0-win-x64\yarn.CMD
    npm: 10.9.0 - ~\bin\node-v23.2.0-win-x64\npm.CMD
  Browsers:
    Edge: Chromium (128.0.2739.67)
    Internet Explorer: 11.0.19041.4355
  npmPackages:
    @vitejs/plugin-react: ~4.3.3 => 4.3.3
    @vitest/coverage-v8: ~2.1.5 => 2.1.5
    vite: ~5.4.11 => 5.4.11
    vitest: ~2.1.5 => 2.1.5

Used Package Manager

yarn

Validations

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

[hi-ogawa]

As this looks more like a feature of happy-dom, can you open an issue there?

On Vitest, you can probably try overwriting fetch (and other) globals back to undici by following

import { fetch } from "undici"
globalThis.fetch = fetch;