Add github action to run formatter for you (#1219)

.github/workflows/format-pr.yml

@@ -0,0 +1,61 @@
+name: Format
+
+on:
+  issue_comment:
+    types: [created]
+
+concurrency: ${{ github.workflow }}-${{ github.ref }}
+
+# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
+permissions:
+  id-token: write
+  contents: write
+  pull-requests: write
+
+jobs:
+  # Create PR
+  pr_commented:
+    name: Format comment
+    if: ${{ github.event.issue.pull_request && contains(github.event.comment.body, '/cadleng format') }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@v5
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: 'Starting formatter! See progress [here](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})'
+            })
+
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Checkout Pull Request
+        run: hub pr checkout ${{ github.event.issue.number }}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Use Node.js node 18.x
+        uses: actions/setup-node@v3
+        with:
+          node-version: 18.x
+
+      - name: Install dependencies
+        run: npx @microsoft/rush update
+
+      - name: Build necessary packages
+        run: npx @microsoft/rush build  --to @cadl-lang/prettier-plugin-cadl
+
+      - name: Format
+        run: npx @microsoft/rush format
+
+      - name: Commit
+        run: |
+          git config --global user.name 'Cadl Eng Bot'
+          git config --global user.email 'microsoft@users.noreply.github.com'
+          git commit -am "Format"
+
+      - name: Push
+        run: git push

CONTRIBUTING.md

@@ -292,6 +292,14 @@ As a contributor you can run the following command to trigger the build and crea
 /azp run Cadl Pull Request Try It
 ```
 
+## Run formatter
+
+Trigger a workflow that will format the code, commit and push.
+
+```
+/cadleng format
+```
+
 # Cadl website
 
 ## Publish website to github.io

cspell.yaml

@@ -12,6 +12,7 @@ words:
   - blockless
   - cadl
   - cadleditor
+  - cadleng
   - Contoso
   - CRUDL
   - dogfood