test: enable test coverage

.github/workflows/test.yml

@@ -71,6 +71,78 @@ jobs:
       - name: Test
         id: test
         run: |
-          pnpm test:vitest --shard=${{ matrix.shardIndex}}/${{ matrix.shardTotal }}
+          ARGS="--shard=${{ matrix.shardIndex}}/${{ matrix.shardTotal }}"
+          if [ "${{ matrix.node }}" == "20" ]; then
+            # We only gather coverage from a single Node version.
+            # We pass in `--reporter=blob` so that we can combine the results from all shards.
+            ARGS="$ARGS --coverage --reporter=default --reporter=blob"
+          fi
+          pnpm test:vitest $ARGS
         env:
           GITHUB_SHARD_IDENTIFIER: ${{ matrix.shardIndex }}-${{ matrix.shardTotal }}
+
+      - name: Upload blob report to GitHub Actions Artifacts
+        if: ${{ !cancelled() && matrix.node == '20' }}
+        uses: actions/upload-artifact@v4
+        with:
+          name: blob-report-${{ github.run_id }}-${{ matrix.shardIndex }}
+          path: '.vitest-reports/*'
+          include-hidden-files: true
+          retention-days: 1
+
+  report-coverage:
+    if: ${{ !cancelled() }}
+    needs: test
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - uses: pnpm/action-setup@v4
+        name: Install pnpm
+        id: pnpm-install
+        with:
+          run_install: false
+
+      - name: Get pnpm store directory
+        id: pnpm-cache
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path)" >> $GITHUB_OUTPUT
+
+      - name: Cache node modules
+        id: cache-node-modules
+        uses: actions/cache@v4
+        env:
+          cache-name: cache-node-modules
+        with:
+          path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ env.cache-name }}-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            v1-${{ runner.os }}-pnpm-store-${{ env.cache-name }}-
+            v1-${{ runner.os }}-pnpm-store-
+            v1-${{ runner.os }}-
+
+      - name: Install project dependencies
+        run: pnpm install
+
+      - name: "Download coverage artifacts"
+        uses: actions/download-artifact@v4
+        with:
+          path: .vitest-reports
+          pattern: blob-report-${{ github.run_id }}-*
+          merge-multiple: true
+
+      - name: Merged report
+        run: |
+          pnpm vitest run --merge-reports --coverage
+
+      - name: Report coverage
+        uses: davelosert/vitest-coverage-report-action@v2
+

.gitignore

@@ -8,6 +8,9 @@ pids
 *.pid
 *.seed
 
+# Combined blobs used from Vitest sharding
+.vitest-reports
+
 # Directory for instrumented libs generated by jscoverage/JSCover
 lib-cov
 

package.json

@@ -126,6 +126,7 @@
     "@typescript-eslint/eslint-plugin": "^7.18.0",
     "@typescript-eslint/parser": "^7.18.0",
     "@vitejs/plugin-react": "^4.3.3",
+    "@vitest/coverage-v8": "^2.1.1",
     "cac": "^6.7.12",
     "chalk": "^4.1.2",
     "depcheck": "^1.4.7",

vitest.config.mts

@@ -0,0 +1,14 @@
+// eslint-disable-next-line import/no-extraneous-dependencies, import/no-unassigned-import
+import '@vitest/coverage-v8'
+
+import {defineConfig} from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    coverage: {
+      provider: 'v8',
+      reporter: ['html', 'json-summary'],
+      include: ['**/packages/**/src/**'],
+    },
+  },
+})