build: add deployment previews for vega-lite documentation site

.github/workflows/deployment-preview.yml

@@ -0,0 +1,80 @@
+# .github/workflows/deployment-preview.yml
+name: Deploy PR previews
+
+on:
+  pull_request:
+    types:
+      - opened
+      - reopened
+      - synchronize
+      - closed
+      # TODO: should this be rerun on new commits?
+
+concurrency: preview-${{ github.ref }}
+
+jobs:
+  # TODO: do we still want to run these on dependabot/non-human branches?
+  deploy-preview-docs:
+    if: github.event.action != 'closed'
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      # Copied from a section of release-docs-and-schema.yml
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          cache: 'yarn'
+          node-version: latest
+
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '2.7' # Not needed with a .ruby-version file
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+
+      - name: Install NPM dependencies
+        run: yarn --frozen-lockfile
+
+      - name: Prebuild website
+        run: yarn presite
+
+      - name: Main site build script. Might need to bundle install
+        shell: bash
+        run: |
+          # Install bundle dependencies first
+          pushd site && bundle install && popd
+          # yarn build uses the wrong shell for some reason?
+          pushd site && bundle exec jekyll build && popd
+          # yarn build:jekyll
+
+      # - name: Build with Jekyll
+      #   uses: actions/jekyll-build-pages@v1
+      #   with:
+      #     source: site
+      #     destination: _site
+      # End copy from a section of release-docs-and-schema.yml
+
+      # https://github.com/actions/upload-pages-artifact?tab=readme-ov-file#file-permissions
+      # - name: Fix permissions
+      #   run: |
+      #     chmod -c -R +r "_site/" | while read line; do
+      #       echo "::warning title=Invalid file permissions automatically fixed::$line"
+      #     done
+
+      - name: Deploy preview and post github comment
+        uses: rossjrw/pr-preview-action@v1
+        with:
+          source-dir: site/_site
+          deploy-repository: vega/vega-lite-pr-previews
+          # TODO: ask Dom to create a token for this
+          token: ${{ secrets.PREVIEW_TOKEN }}
+
+  cleanup-preview-docs:
+    if: github.event.action == 'closed'
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Cleanup pr-preview
+        uses: rossjrw/pr-preview-action@v1
+        with:
+          source-dir: site/_site

src/compile/compile.ts

@@ -70,6 +70,8 @@ export interface CompileOptions {
  * @returns         An object containing the compiled Vega spec and normalized Vega-Lite spec.
  */
 export function compile(inputSpec: TopLevelSpec, opt: CompileOptions = {}) {
+  console.log('Check if this is the preview site!', inputSpec);
+
   // 0. Augment opt with default opts
   if (opt.logger) {
     // set the singleton logger to the provided logger