Testing Strategy v1

Three layers: Vitest (unit, jsdom), Playwright (E2E, browser matrix), Lighthouse (perf + a11y). Coverage ≥ 90% global, 100% on every compiler Pass. Visual regression runs only on chrome-desktop because cross-OS font rendering produces false positives elsewhere.

Unit (Vitest)

just tu  # fast unit
just tc  # full + coverage

• Environment: jsdom.
• Setup: tests/setup.ts mocks Shiki highlighter, WebGPU APIs, localStorage, ResizeObserver, IntersectionObserver.
• Coverage provider: v8.
• Fast mode (VITEST_FAST=true) skips slow UI specs:
  • src/routes/**/*.svelte.test.ts
  • src/shared/ui/**/*.test.ts
  • src/widgets/**/ui/*.test.ts
  • src/features/background/ui/*.test.ts
  • src/widgets/search/ui/*.test.ts
• Coverage exclusions: test files, .d.ts, index.ts re-exports, app shell, data/interface files.

Integration / E2E (Playwright)

just ti           # local Playwright
just bs           # update snapshots (current OS)
just baseline ci  # update snapshots in Docker (Linux parity)

• Local config: playwright.config.ts — chrome-desktop only, webServer via bun run serve:playwright.
• CI config: playwright.ci.config.ts — matrix: chrome-desktop, chrome-mobile, firefox-desktop, firefox-mobile.
• Spec dependencies: tests/e2e/homepage.spec.ts runs first per browser; other specs depend on it.
• Visual regression: chrome-desktop only (tests/e2e/post-ux.spec.ts).
• A11y: @axe-core/playwright assertions in tests/e2e/a11y.spec.ts.

Lighthouse

just test lhci

• Config: .lighthouserc.json.
• URLs: /, /blog/, /about/.
• Asserts: performance ≥ 0.9, accessibility ≥ 0.9, SEO ≥ 0.9, best-practices ≥ 0.9.
• Skips: PWA, HTTPS, and legacy JS audits.

Test Commands

What	Full command	Shortcut
Fast unit tests	just test unit	just tu
Unit + coverage	just test coverage	just tc
Playwright local	just test integration	just ti
All tests	just test all	just ta
Lighthouse CI	just test lhci	—
Bundle budget	just test bundle	—
Update snapshots (local OS)	just baseline snapshots	just bs
Update snapshots (CI parity)	just baseline ci	—
Update bundle baseline	just baseline bundle	just bb

Agents should use shortcuts to save tokens. Humans can use full commands for clarity.

Test Rules

• No code merges without a corresponding test file.
• Mocks only at system boundaries (WebGPU, fetch, localStorage). Never mock internal modules.
• Compiler Passes require 100% coverage — non-negotiable.
• Visual snapshots committed only after manual diff inspection of the failure artifact.

Where things live

Kind	Path
Vitest setup	tests/setup.ts
Vitest config	vite.config.ts (vitest section)
Playwright local config	playwright.config.ts
Playwright CI config	playwright.ci.config.ts
Playwright specs	tests/e2e/*.spec.ts
Lighthouse config	.lighthouserc.json
Lighthouse runner	scripts/run-lhci.mjs
Bundle report	scripts/bundle-report.mjs
Coverage output	target/coverage/
Playwright report	target/playwright-report/

When something breaks

→ Troubleshooting → Snapshot mismatch.

Related

• Infrastructure
• Conventions
• Troubleshooting