feat: add manual browser testing for the built bundle

[kdaviduik]

What

Adds test-manual/index.html that loads the locally built bundle (lib/buybutton.umd.js) instead of the CDN script and renders real buy buttons from live stores.

Example

Why

The unit test suite (794 tests) verifies component logic, but doesn't render actual buy buttons in a browser. This enables reviewers to:

• Verify the built bundle loads correctly
• See real buy buttons render with products from live stores
• Test cart interactions, modals, and checkout flows
• Confirm changes don't break visual rendering or API communication

This is especially important given the scale of changes we will be making to this package.

Interim Solution

This manual testing approach is an interim solution in the complete absence of automated browser testing. The codebase currently uses Testem/Mocha for unit tests only — no e2e or browser rendering tests exist.

Adding Playwright or Vitest now would complicate the ongoing modernization work (TypeScript migration, ESLint 9, browser targets). Once this stack lands and the foundation stabilizes, automated browser testing can be added as a follow-up:

1. Vitest — to replace Testem/Mocha for unit tests (better TS support, faster)
2. Playwright — to automate the manual test page for CI-enforced browser verification

This manual test page provides a foundation for future Playwright tests.

How to Use

pnpm install
pnpm build
pnpm serve
open http://localhost:8080/test-manual/

Screen.Recording.2026-08-10.at.10.54.58.AM.mov

Tests Included

Test	Type	Store	Purpose
1	Product	kara-daviduik	Basic product with default styling
2	Collection	kara-daviduik	Collection grid rendering
3	Product	hydrogen-migration	Cross-store verification

[kdaviduik]

• feat!: migrate ESLint 3 to ESLint 9 flat config with typescript-eslint #950
• feat!: drop IE 11 and modernize browser targets #946
• feat: add manual browser testing for the built bundle #954 👈 (View in Graphite)
• chore: enable automatic CHANGELOG generation via Changesets #945 : 1 other dependent PR (#951 )
• feat: migrate Yarn v1 to pnpm #942
• fix: remove Firefox requirement from testem CI config and fix view tests #943
• fix: run CI on all pull requests, not just those targeting main #944
• docs: revise TypeScript migration PRD and task list for tech stack modernization #941
• chore: add CODEOWNERS for developer-platforms team #947
• main

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[graygilmore]

🎩 went well couple of questions both here and in Slack

[graygilmore]

Can we leverage dev instead? Or since it's a public repo we want to stay generic?

Suggested change

	pnpm install
	dev up

[kdaviduik]

I agree leveraging dev would be helpful, I'll add dev support in the future as a separate PR

[EvilGenius13]

Thanks @kdaviduik, this seems like a helpful addition!

Quick note that I tophatted myself and due to port conflicts the server automatically adjusted to 8082 for me. Not sure if we want to be more loose on the info surrounding the ports or just say to use the server info that the terminal spits out on start up. (maybe dev up could solve this by outputting the final address to click aswell).

[kdaviduik]

Thanks @EvilGenius13, good callout! Updated the places that mentioned a specific port in this PR. There is more work to do on that front as a separate PR (like updating the port in dev.yml for the open command) but that's out of scope for this PR and will be a follow up