Error when using @vue/compat.

Describe the bug

When using the build @vue/compat and installing it according to the migration guide (ie: using alias in vite), the tests fail with the following message:

TypeError: Cannot read properties of null (reading 'isCE')

This happens when you try to render a component with a slot.

Looking around, I have found this is a very similar issue than: https://github.com/vitest-dev/vitest/issues/1886. Following the instructions here, I have managed to add @vue/test-utils to the inlined dependencies (as you can see in the reproduction).

The issue happens whenever adding @testing-library/vue. The tests using testing-library now also fail due to the same reason. At this point I have tried multiple combinations of inlining dependencies without much luck.

If I manually edit the node_modules/@vue/test-utils/dist/vue-test-utils.cjs.js file and change the vue import to @vue/compat, both of the tests work.

I suspect the solution might be simpler and would also happily contribute in case its needed.

Thank you!

Reproduction

https://github.com/bernardocorbella/vue-compat-vite-slot-error

You can see the test file in which one test passes and one fails.

System Info

System:
    OS: macOS 14.1.1
    CPU: (8) arm64 Apple M1
    Memory: 75.09 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 18.18.2 - ~/.volta/tools/image/node/18.18.2/bin/node
    Yarn: 1.22.19 - ~/.volta/tools/image/yarn/1.22.19/bin/yarn
    npm: 9.4.0 - ~/.volta/tools/image/npm/9.4.0/bin/npm
    pnpm: 8.11.0 - ~/.volta/bin/pnpm
  Browsers:
    Chrome: 119.0.6045.159
    Safari: 17.1
  npmPackages:
    @vitejs/plugin-vue: ^4.4.0 => 4.5.0 
    vite: ^4.4.11 => 4.5.0 
    vitest: ^0.34.6 => 0.34.6

Used Package Manager

pnpm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start with the linked reproduction and its src/components/tests/HelloWorld.spec.ts test file, then run the failing slot test with the reported @vue/compat, Vite, Vitest, and testing-library setup. Compare the passing and failing cases while checking dependency inlining and the import behavior described in the issue; done means both tests pass without manually editing node_modules.