DevTools guard for jsdom could be improved

[tkalmar]

i recently stumbled upon
https://github.com/vuejs/core/blame/623bfb29a23c36bf935e7faefa64d1baa69d465c/packages/runtime-core/src/devtools.ts#L67
after switching my vitest environment from jsdom to happy-dom.
Wouldn't it be better if devtools get disabled if NODE_ENV=== 'test'? Only testing for jsdom there is very specific and what happens if jsdom replaces the user-agent? or someone mocks the user-agent with ohter strings? I personally find this very fragile.

[krishkhinchi]

Hi @tkalmar,

Good catch. You’re right that relying on a jsdom-specific user-agent check is quite fragile and environment-dependent. Disabling devtools based on NODE_ENV === "test" would be a more robust and explicit signal, especially now that alternatives like happy-dom are common and user-agent strings can be spoofed or changed.

A possible middle ground could be:

• Prefer NODE_ENV === "test" (or a similar explicit flag) to disable devtools by default in test environments.
• Keep the jsdom check only as a fallback for legacy cases.

This would make the behavior more predictable and less coupled to a specific DOM implementation.

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If this addresses your concern, please mark this as answered. If not, let me know what part you’d like to dig into further.

[tkalmar]

Thanks for the feedaback!
Workaround which worked for me was:

beforeEach(() => {
  // disable hook registration of vue devtools as it would add an setTimeoutSpy call
  (globalThis as any).__VUE_DEVTOOLS_GLOBAL_HOOK__ = {
    emit: vi.fn(),
  };
});