Add a workflow to test building on pull requests

Author: weirdwater

.github/workflows/BuildPackages.yml

@@ -0,0 +1,90 @@
+name: Build Packages
+
+on:
+  pull_request:
+    branches:
+      - master
+    paths:
+      - pnpm-lock.yaml
+      - packages/*
+
+jobs:
+  discover:
+    name: Discover packages to build
+    runs-on: ubuntu-latest
+    outputs:
+      packages: ${{ steps.export.outputs.packages }}
+    steps:
+      - name: Checking-out code
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+        with:
+          fetch-depth: 0
+
+      - name: Find Publishable Packages
+        run: |
+          packages=$(
+            (for package in $(find ./packages -type f -name package.json -depth 2); do
+              if [[ $(jq '.private != true' "$package") == "true" ]]; then
+                printf '"%s"\n' $(sed -E 's|^./packages/(.*)/package.json$|\1|' <<< "$package")
+              fi
+            done) | jq -c --slurp '.'
+          )
+          printf "::debug::All packages: %s" $packages
+
+      - name: Find Changed Packages
+        run: |
+          changed=$(
+            git diff --name-only ${{ github.base_ref }}..HEAD \
+          | grep "packages/.*"                                \
+          | sed -E 's|^packages/([^/]*).*$|"\1"|g'            \
+          | jq -c --slurp '. | unique'
+          )
+          printf "::debug::Changed packages: %s" $changed
+
+      - name: List Packages to Build
+        id: export
+        run: |
+          lock_changed = $(git diff --name-only ${{ github.base_ref }}..HEAD | grep "pnpm-lock.yaml")
+
+          if [[ -n "$lock_changed" ]]; then
+            echo "Build all packages"
+            echo "packages=$packages" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          to_build=$(jq -n -c --argjson packages "$packages" --argjson changed "$changed" '$packages - ($packages - $changed)')
+          printf "::debug::Packages to build: %s" "$to_build"
+          echo "packages=$to_build" >> "$GITHUB_OUTPUT"
+
+  build:
+    name: Build NPM packages
+    runs-on: ubuntu-latest
+    needs: discover
+    if: ${{ needs.discover.outputs.packages != '[]' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        package: ${{ fromJSON(needs.discover.outputs.packages) }}
+    steps:
+      - name: Check-out code
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@a7487c7e89a18df4991f7f222e4898a00d66ddda #v4.1.0
+        with:
+          version: 10
+
+      - name: Setup node
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
+        with:
+          node-version-file: ".nvmrc"
+          cache: 'pnpm'
+
+      - name: Install dependencies
+        working-directory: ./packages/${{ matrix.package }}
+        run: pnpm install
+
+      - name: Pack package
+        working-directory: ./packages/${{ matrix.package }}
+        run: pnpm pack
+