chore: avoid auto-formatter workflow failing on fork PRs

.github/workflows/format.yml

@@ -1,10 +1,18 @@
 name: Formatter
 
-on: [pull_request]
+on:
+  pull_request:
+    branches:
+      - develop
 
 jobs:
   prettier:
+    # This conditional prevents running the job on PRs from forks; won't
+    # have permissions to commit changes, so the job would fail if it ran.
+    # PRs from forks will instead rely on failing the fmt_check job in test.yml
+    if: github.event.pull_request.head.repo.full_name == github.repository
     runs-on: ubuntu-latest
+    timeout-minutes: 5
     steps:
       - uses: actions/checkout@v4
         with:

.github/workflows/test.yml

@@ -26,6 +26,18 @@ jobs:
           path: axe.js
           retention-days: 1
 
+  fmt_check:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: 'npm'
+      - run: npm ci
+      - run: npm run fmt:check
+
   test_node:
     strategy:
       matrix:

package.json

@@ -112,6 +112,7 @@
     "sri-update": "grunt build && node build/sri-update && git add sri-history.json",
     "sri-validate": "node build/sri-update --validate",
     "fmt": "prettier --write .",
+    "fmt:check": "prettier --check .",
     "prepare": "husky && npm run patch",
     "prebuild": "node ./build/check-node-version.js",
     "pretest": "node ./build/check-node-version.js",