👷(ci) lint, type-check and test yhub-server and the loadtest packages

yhub-server, src/loadtest/swarm and src/loadtest/canary are standalone
TypeScript packages, each with its own package.json and yarn.lock, outside
the src/frontend workspaces. The frontend workflow never saw them, and the
backend job only built yhub-server to serve its integration tests, so their
lint, type check and unit tests never ran in the CI.

A matrix job now runs `yarn lint`, `yarn typecheck` and `yarn test` for
each of them, and installs Chromium for the canary, whose tests drive a
real browser.

.github/workflows/impress.yml

@@ -108,6 +108,44 @@ jobs:
       - name: Lint code with pylint
         run: uv run pylint impress demo core
 
+  # The standalone TypeScript packages: each has its own package.json and
+  # yarn.lock, outside the src/frontend workspaces, so the frontend workflow
+  # never lints nor tests them.
+  lint-test-node-packages:
+    name: lint-test-node-packages (${{ matrix.package }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        package:
+          - src/yhub-server
+          - src/loadtest/swarm
+          - src/loadtest/canary
+    defaults:
+      run:
+        working-directory: ${{ matrix.package }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - name: Set up Node
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6
+        with:
+          node-version: "22.x"
+          cache: yarn
+          cache-dependency-path: ${{ matrix.package }}/yarn.lock
+      - name: Install dependencies
+        run: yarn install --frozen-lockfile
+      # the canary tests drive a real Chromium
+      - name: Install Chromium
+        if: matrix.package == 'src/loadtest/canary'
+        run: npx playwright install --with-deps chromium
+      - name: Lint
+        run: yarn lint
+      - name: Check types
+        run: yarn typecheck
+      - name: Run tests
+        run: yarn test
+
   test-back:
     runs-on: ubuntu-latest
     needs: install-dependencies

CHANGELOG.md

@@ -64,6 +64,7 @@ and this project adheres to
   `COLLABORATION_VERSION_GRANULARITY_MS`
 - ✨(frontend) keep a local copy of documents, so they open and stay editable
   offline
+- 👷(ci) lint, type-check and test yhub-server and the loadtest packages
 - 🐛(frontend) stop the service worker from caching the collaboration server's
   rest api