Swap jsdom for happy-dom test env (ui-extensions)

[amcaplan]

Swap jsdom → happy-dom test environment in ui-extensions packages

Why: Part of an initiative to cut low-value dependency churn (jsdom: ~2 Dependabot bumps / 24 months). happy-dom is a lighter, faster vitest browser environment with no feature gap for these packages' test suites.

What changed (devDep-only — 4 files):

• packages/ui-extensions-dev-console/vite.config.mts — vitest environment: 'jsdom' → 'happy-dom'
• packages/ui-extensions-server-kit/vite.config.mts — vitest environment: 'jsdom' → 'happy-dom'
• both package.json — removed "jsdom": "^25.0.0", added "happy-dom": "^20.10.1" to devDependencies
• patch changeset for @shopify/ui-extensions-server-kit (dev-console is "private": true)

Validation: All tests pass under happy-dom with no test-code changes — the swap is transparent.

Package	Tests	Lint
ui-extensions-dev-console	6 files / 28 tests ✅	✅
ui-extensions-server-kit	7 files / 61 tests ✅	✅

(server-kit type-check ✅. dev-console has pre-existing ReactNode type errors in .tsx files untouched by this change — a test-environment/devDep swap cannot affect those.)

Surface impact: devDependencies only — the published artifact of @shopify/ui-extensions-server-kit is unaffected.

🤖 AI-generated draft — needs human review before merge.

[Copilot]

Pull request overview

This PR switches the Vitest browser-like test environment for the ui-extensions packages from jsdom to happy-dom, aiming to reduce dependency churn while keeping test behavior unchanged.

Changes:

• Update Vitest config in ui-extensions-dev-console and ui-extensions-server-kit to use environment: 'happy-dom'.
• Replace jsdom with happy-dom in the packages’ devDependencies.
• Update the lockfile and add a changeset for @shopify/ui-extensions-server-kit.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pnpm-lock.yaml	Updates dependency graph to reflect happy-dom adoption and removal of direct jsdom devDeps in the affected packages.
packages/ui-extensions-server-kit/vite.config.mts	Switch Vitest environment from jsdom to happy-dom.
packages/ui-extensions-server-kit/package.json	Replace jsdom with happy-dom in devDependencies.
packages/ui-extensions-dev-console/vite.config.mts	Switch Vitest environment from jsdom to happy-dom.
packages/ui-extensions-dev-console/package.json	Replace jsdom with happy-dom in devDependencies.
.changeset/swap-jsdom-happy-dom-ui-extensions.md	Adds a patch changeset describing the test-environment/devDependency swap.

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[gonzaloriestra]

The new dependency is 2x heavier (1.17MB vs 0.55MB) and has 7x more releases (185 vs 24 in the last 2 years).

What's the point?

[amcaplan]

@gonzaloriestra you have to consider transitive dependencies.

[gonzaloriestra]

Right, but:

• This is a dev dependency, so it won't affect the bundle size
• Jsdom is still present in the lockfile (used by eslint-plugin-cli and vitest)
• We are adding a new dependency

So I'm still not sure about the purpose of this 😅

What about just deduplicating jsdom instead? We have 25.0.1 and 28.1.0 now

[gonzaloriestra]

Ok, now that jsdom was completely removed, I guess it makes sense to switch in order to reduce the number of transitive deps 👍

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