Add test coverage reports

.github/workflows/pr_checks.yaml

@@ -64,6 +64,9 @@ jobs:
   unit-tests:
     name: Unit Tests
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write # required by the coverage report action to comment on the PR
     steps:
       - name: Checkout
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -82,8 +85,16 @@ jobs:
       - name: Install Playwright browsers
         run: npx playwright install --with-deps chromium
 
-      - name: Run unit tests
-        run: npm run test:unit
+      - name: Run unit tests with coverage
+        run: npm run test:unit:coverage
+
+      # Reports overall + diff coverage as a job summary and a sticky PR comment.
+      # Informational only — coverage is not currently enforced as a merge gate.
+      - name: Coverage report
+        if: always() && github.event_name == 'pull_request'
+        uses: davelosert/vitest-coverage-report-action@c4bbc33a89b7ace0e63d35f1f7d4bcee31155a73 # v2.13.0
+        with:
+          file-coverage-mode: changes
 
   e2e-with-garage:
     name: E2E Tests with Garage S3

package.json

@@ -15,6 +15,7 @@
     "lint": "prettier --check --ignore-path .prettierignore . && eslint .",
     "lint:fix": "prettier --write --ignore-path .prettierignore . && eslint . --fix",
     "test:unit": "vitest run",
+    "test:unit:coverage": "vitest run --coverage",
     "test:e2e": "node --env-file=.env.test node_modules/.bin/vite build && playwright test",
     "test:e2e:garage": "./e2e/run-garage-tests.sh",
     "test:e2e:ui": "playwright test --ui",

vite.config.ts

@@ -19,8 +19,17 @@ export default defineConfig({
   test: {
     coverage: {
       provider: 'v8',
-      reporter: ['json', 'json-summary'],
-      reportsDirectory: './coverage'
+      reporter: ['text', 'html', 'json', 'json-summary'],
+      reportsDirectory: './coverage',
+      // Without `include`, files that no test ever imports are silently omitted from the
+      // report instead of showing as 0% — set it so untested modules are actually visible.
+      include: ['src/**/*.{ts,svelte}'],
+      exclude: [
+        'src/**/*.d.ts',
+        'src/lib/paraglide/**',
+        'src/lib/editor/generated/**',
+        'src/lib/server/migrations/**'
+      ]
     },
     expect: { requireAssertions: true },
     projects: [