CI Automation: Add comment with PR preview link

Author: adamziel

.github/workflows/preview-comment.yml

@@ -0,0 +1,74 @@
+# Responsible for making comments on pull requests, such as commenting for first time contributors.
+name: Pull Request Comments
+
+on:
+  pull_request_target:
+    types: [ 'opened' ]
+
+# Disable permissions for all available scopes by default.
+# Any needed permissions should be configured at the job level.
+permissions: {}
+
+jobs:
+  # Leaves a comment on a pull request with a link to test the changes in a WordPress Playground instance.
+  playground-details:
+    name: Comment on a pull request with Playground details
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+      pull-requests: write
+    steps:
+      - name: Leave a comment about testing with Playground
+        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
+        with:
+          script: |
+            const fs = require( 'fs' );
+            const issue_number = context.payload.pull_request.number;
+            const branch_name = context.payload.pull_request.head.ref;
+
+            // First, find a blueprint.json file in the pull request
+            const blueprintFile = ( await github.rest.pulls.listFiles( commentInfo ) ).data.filter( file => file.filename.endsWith( '/blueprint.json' ) )[0];
+            if ( !blueprintFile ) {
+              return;
+            }
+
+            // Comments are only added after the first successful build. Check for the presence of a comment and bail early.
+            const commentInfo = {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number,
+            };
+
+            const comments = ( await github.rest.issues.listComments( commentInfo ) ).data;
+
+            for ( const currentComment of comments ) {
+              if ( currentComment.user.type === 'Bot' && currentComment.body.includes( 'Test using WordPress Playground' ) ) {
+                commentInfo.comment_id = comment.id;
+                break;
+              }
+            };
+
+            // No comment was found. Create one.
+            commentInfo.body = `## Test using WordPress Playground
+            The changes in this pull request can previewed and tested using a [WordPress Playground](https://developer.wordpress.org/playground/) instance.
+
+            [WordPress Playground](https://developer.wordpress.org/playground/) is an experimental project that creates a full WordPress instance entirely within the browser.
+
+            ### Some things to be aware of
+            - The Plugin and Theme Directories cannot be accessed within Playground.
+            - All changes will be lost when closing a tab with a Playground instance.
+            - All changes will be lost when refreshing the page.
+            - A fresh instance is created each time the link below is clicked.
+            - Every time this pull request is updated, a new ZIP file containing all changes is created. If changes are not reflected in the Playground instance,
+            it's possible that the most recent build failed, or has not completed. Check the [list of workflow runs to be sure](https://github.com/WordPress/wordpress-develop/actions/workflows/wordpress-playground.yml).
+
+            For more details about these limitations and more, check out the [Limitations page](https://wordpress.github.io/wordpress-playground/limitations/) in the WordPress Playground documentation.
+
+            [Test this pull request with WordPress Playground](https://playground.wordpress.net/?blueprint-url=https://raw.githubusercontent.com/adamziel/blueprints/${ branch_name }/${ blueprintFile }).
+            `;
+
+            if ( commentInfo.comment_id ) {
+              await github.rest.issues.updateComment( commentInfo );
+            } else {
+              await github.rest.issues.createComment( commentInfo );
+            }