test(bundler): migrate bundler tests from Karma to Jest + Puppeteer #6436

gnbm · 2025-10-24T10:57:31Z

Replace Karma (Jasmine) bundler tests with Jest + Puppeteer to keep real-browser parity while simplifying setup.

What is the current behavior?

Karma is legacy and adds infra complexity.
Jest + Puppeteer provides the same real-browser guarantees with simpler tooling and better DX.
Aligns with existing Stencil testing infra and conventions.

GitHub Issue Number: N/A

What is the new behavior?

What Changed

test/bundler/vite-bundle-test/vite-bundle.spec.ts
- New Jest + Puppeteer test: launches headless Chromium, serves dist/, waits for hydration, asserts Shadow DOM text.
- Uses Node’s node:http, node:fs, node:path for cross-platform static serving.
- TypeScript with explicit Browser/Server types.
test/bundler/jest.config.js
- Restored ts-jest config for TypeScript specs.
test/bundler/* package.json clean scripts
- Replaced rm -rf with Node fs.rmSync for Windows/macOS/Linux compatibility.
test/bundler/readme.md
- Updated docs to reflect Jest + Puppeteer approach.
Removed Karma files
- test/bundler/karma.config.ts
- test/bundler/karma-stencil-utils.ts
Root script (package.json)
- Added test.jest.lowmem for CI/local stability (8GB heap, 50% workers).

Parity With Karma
✅ Real Chromium via Puppeteer (not jsdom)
✅ Static serving of Vite output, no dev-server coupling
✅ Shadow DOM assertions after hydration
✅ Cross-platform (Windows/macOS/Linux)

CI/Local Stability

Added npm run test.jest.lowmem:
- node --max-old-space-size=8192 --experimental-vm-modules ./node_modules/jest/bin/jest.js --maxWorkers=50%
Mitigates Windows/CI memory pressure observed during large Jest runs.

Documentation

Does this introduce a breaking change?

Yes
No

Testing

From repo root:
- Build: npm run build
- Bundler tests (full flow): cd test/bundler && npm run start
- Root Jest (stable mode): npm run test.jest.lowmem

Other information

Notes:

Playwright was evaluated; Jest + Puppeteer chosen for consistency with existing Stencil testing and minimal change footprint.
Verified on Windows; node: imports and Node static server ensure cross-platform behavior.

…S config\n\n- Serve Vite dist via Node static server (parity with Karma)\n- Real browser with Puppeteer; wait for .hydrated before asserting\n- Restore ts-jest config and explicit TS types\n- Keep node: imports and cross-platform clean scripts

…CI/local stability

…tation icons to jobs

…n- Force public registry and disable always-auth\n- Delete inherited auth token for registry\n- Write clean ~/.npmrc for job

… unsupported option errors\n\n- Avoid 'always-auth' setter; write exact keys to ~/.npmrc\n- Keep public registry and blank token

…to avoid E401\n\n- Write .npmrc in test/bundler and vite-bundle-test\n- Export NPM_* env vars to ensure no token is used

… flags to avoid E401 during npm ci

…y at npm ci call sites

…ning bundler tests

… public npmrc and cleared tokens

…ean userconfig and explicit registry

…en-free .npmrc (option A)

…running Jest on compiled output (no ts-jest install)

…mpiled JS spec

… compiled spec can import it

…stall chrome) to satisfy runtime

- Remove debug logging from vite-bundle.spec.ts (test is stable) - Reduce wait timeouts back to 10s (original timeouts sufficient) - Add .gitignore for CI-generated artifacts (dist-spec, jest.config.ci.js, tsconfig.test.json) - Remove redundant puppeteer install step from CI workflow (already in root deps) - Simplify Chrome download step to use existing puppeteer installation

Reinstall puppeteer explicitly before downloading Chrome to ensure puppeteer-core is properly installed. In some CI environments, npm ci doesn't correctly install peer dependencies, leading to module resolution errors when Jest tries to require('puppeteer').

gnbm · 2025-10-27T11:44:48Z

@johnjenkins tried a different approach.
Some checks didn't run in the PR, but I lack context.
Hope someone can review this since I still have a lot to learn on this project :)

johnjenkins · 2025-10-27T12:40:07Z

@johnjenkins tried a different approach. Some checks didn't run in the PR, but I lack context. Hope someone can review this since I still have a lot to learn on this project :)

Sorry - pipelines are not my strong-suite :/
Maybe github has some caching on the job names?

gnbm · 2025-10-27T12:55:08Z

@johnjenkins tried a different approach. Some checks didn't run in the PR, but I lack context. Hope someone can review this since I still have a lot to learn on this project :)

Sorry - pipelines are not my strong-suite :/ Maybe github has some caching on the job names?

Mine neither. I'll wait for some feedback on this PR from the community. Cheers

gnbm added 5 commits October 22, 2025 23:44

Migrate Karma tests to Jest + Puppeteer runner

b4ca4cc

chore(test): add test.jest.lowmem script (8GB heap, 50% workers) for …

e056505

…CI/local stability

Update GitHub workflows to use latest dependencies and added represen…

24c362a

…tation icons to jobs

Merge branch 'main' into chore/karma-tests-migration

8da96e6

gnbm added the dependencies Pull requests that update a dependency file label Oct 24, 2025

gnbm added 23 commits October 24, 2025 13:40

ci(bundlers): sanitize npm config to avoid E401 on public registry\n\…

307902c

…n- Force public registry and disable always-auth\n- Delete inherited auth token for registry\n- Write clean ~/.npmrc for job

ci(bundlers): write clean ~/.npmrc instead of npm config set to avoid…

2d74868

… unsupported option errors\n\n- Avoid 'always-auth' setter; write exact keys to ~/.npmrc\n- Keep public registry and blank token

chore(prettier): format test-bundlers workflow

3673637

ci(bundlers): force public registry in subfolders and clear auth env …

8024e31

…to avoid E401\n\n- Write .npmrc in test/bundler and vite-bundle-test\n- Export NPM_* env vars to ensure no token is used

ci(bundlers): run bundler job with explicit user npmrc and --registry…

14e8ae1

… flags to avoid E401 during npm ci

ci(bundlers): rollback custom npmrc flow; enforce public registry onl…

eaec078

…y at npm ci call sites

ci(bundlers): install test/bundler dev deps (ts-jest/jest) before run…

8e51bf6

…ning bundler tests

ci(bundlers): install test/bundler deps with explicit --userconfig to…

07b1dbf

… public npmrc and cleared tokens

ci(bundlers): avoid E401 by installing ts-jest/jest via npm i with cl…

3210b6b

…ean userconfig and explicit registry

ci(bundlers): install ts-jest/jest inside test/bundler with local tok…

eb9ba14

…en-free .npmrc (option A)

ci(bundlers): avoid npm auth entirely by compiling TS spec to JS and …

d6ed492

…running Jest on compiled output (no ts-jest install)

ci(bundlers): run Jest with minimal CI config (no ts-jest) against co…

96e91bc

…mpiled JS spec

ci(bundlers): install puppeteer at repo root with token-free npmrc so…

87f585d

… compiled spec can import it

ci(bundlers): install Chrome for Puppeteer (npx puppeteer browsers in…

15be44a

…stall chrome) to satisfy runtime

Update vite-bundle.spec.ts

07e65e3

Update vite-bundle.spec.ts

e3db859

Update vite-bundle.spec.ts

93637de

Update vite-bundle.spec.ts

4eb3ecf

Update vite-bundle.spec.ts

0047dd4

Update vite-bundle.spec.ts

37bae75

Update test-bundlers.yml

ee14a82

gnbm marked this pull request as ready for review October 27, 2025 11:18

gnbm requested a review from a team as a code owner October 27, 2025 11:18

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test(bundler): migrate bundler tests from Karma to Jest + Puppeteer #6436

test(bundler): migrate bundler tests from Karma to Jest + Puppeteer #6436

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gnbm commented Oct 24, 2025

What is the current behavior?

What is the new behavior?

Documentation

Does this introduce a breaking change?

Testing

Other information

Notes:

Uh oh!

gnbm commented Oct 27, 2025

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johnjenkins commented Oct 27, 2025

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gnbm commented Oct 27, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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gnbm commented Oct 27, 2025 •

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