Setup tests

[dotnize]

I plan to implement this in tanstarter-monorepo, but should we implement this here too?

goals:

• minimal
• should be optional and can be ignored, or even removed easily (for MVPs and quick prototypes that don't need tests)
• both focused unit tests and integrated e2e tests
  • components & utils
  • routes
  • server functions

refs:

• Vitest
• Playwright
• https://tanstack.com/router/latest/docs/framework/react/how-to/test-file-based-routing

[sd44]

I'd love to see implementations with Playwright or similar E2E tools. The official TanStack testing utilities often feel incomplete, especially when rigorously testing serverFn and routing logic in real network environments.

[m13v]

for a starter template, keeping tests optional and removable is the right call. what we found works well: put the Playwright config and e2e folder behind a separate package.json script so people can delete the whole thing without breaking the dev workflow. for the Vitest side, testing TanStack Router's file-based routes is much easier if you test the route handlers as pure functions rather than trying to navigate between them. the E2E layer covers the actual routing behavior, so you avoid duplicating test coverage.

[m13v]

for the E2E layer, we open sourced the browser management piece that handles session isolation between parallel test workers, which matters when your tests share a dev server: https://github.com/m13v/browser-lock/blob/main/playwright-lock.sh - keeps Playwright workers from corrupting each other's auth state.