---
phase: 09-ci-pipeline
plan: 01
subsystem: testing
tags: [vitest, playwright, svelte5, coverage, browser-testing]

# Dependency graph
requires:
  - phase: 01-foundation
    provides: SvelteKit project structure with vite.config.ts
provides:
  - Multi-project Vitest configuration (browser + node modes)
  - SvelteKit module mocks ($app/navigation, $app/stores, $app/environment)
  - Test scripts (test, test:unit, test:coverage)
  - Coverage reporting with v8 provider
affects: [09-02, 09-03]

# Tech tracking
tech-stack:
  added: [vitest@4.0.18, @vitest/browser, @vitest/browser-playwright, vitest-browser-svelte, @vitest/coverage-v8]
  patterns: [multi-project-test-config, sveltekit-module-mocking]

key-files:
  created:
    - vitest-setup-client.ts
    - src/lib/utils/filterEntries.test.ts
  modified:
    - vite.config.ts
    - package.json

key-decisions:
  - "Multi-project setup: browser (client) vs node (server) test environments"
  - "Coverage thresholds with autoUpdate initially (no hard threshold yet)"
  - "SvelteKit mocks use simple vi.mock, not importOriginal (avoids SSR issues)"

patterns-established:
  - "*.svelte.test.ts for component tests (browser mode)"
  - "*.test.ts for utility/server tests (node mode)"
  - "Test factory functions for creating test data"

# Metrics
duration: 3min
completed: 2026-02-03
---

# Phase 9 Plan 1: Vitest Infrastructure Summary

**Multi-project Vitest configuration with browser mode for Svelte 5 components and node mode for server/utility tests**

## Performance

- **Duration:** 3 min
- **Started:** 2026-02-03T22:27:09Z
- **Completed:** 2026-02-03T22:29:58Z
- **Tasks:** 3
- **Files modified:** 4

## Accomplishments
- Vitest installed and configured with multi-project setup
- Browser mode ready for Svelte 5 component tests (via Playwright)
- Node mode ready for server/utility tests
- SvelteKit module mocks ($app/*) for test isolation
- Coverage reporting functional (v8 provider, autoUpdate thresholds)
- 17 unit tests proving infrastructure works

## Task Commits

Each task was committed atomically:

1. **Task 1: Install Vitest dependencies and configure multi-project setup** - `a3ef94f` (feat)
2. **Task 2: Create SvelteKit module mocks in setup file** - `b0e8e4c` (feat)
3. **Task 3: Write sample test to verify infrastructure** - `b930f18` (test)

## Files Created/Modified
- `vite.config.ts` - Multi-project Vitest config (client browser mode + server node mode)
- `vitest-setup-client.ts` - SvelteKit module mocks for browser tests
- `package.json` - Test scripts (test, test:unit, test:unit:watch, test:coverage)
- `src/lib/utils/filterEntries.test.ts` - Sample unit test with 17 test cases, 100% coverage

## Decisions Made
- Used v8 coverage provider (10x faster than istanbul, equally accurate since Vitest 3.2)
- Set coverage thresholds to autoUpdate initially - Plan 02 will enforce 80% threshold
- Browser mode uses Playwright provider (real browser via Chrome DevTools Protocol)
- SvelteKit mocks are simple vi.fn() implementations, not importOriginal (causes SSR issues per research)

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered

None

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness
- Test infrastructure ready for Plan 02 (coverage thresholds, CI integration)
- Component test infrastructure ready but no component tests yet (Plan 03 scope)
- filterEntries.test.ts demonstrates node-mode test pattern

---
*Phase: 09-ci-pipeline*
*Completed: 2026-02-03*