perf: check prop only from metadata of demo (#18332)

* perf: check prop  from metadata of demo

* fix: indent

.circleci/config.yml

@@ -66,6 +66,9 @@ references:
       - test_node_15:
           requires:
             - setup
+      - check_metadata:
+          requires:
+            - setup
 
 jobs:
   setup:
@@ -223,6 +226,13 @@ jobs:
       - *install_react
       - run: npm run test-node -- -w 1 -u
 
+  check_metadata:
+    <<: *container_config
+    steps:
+      - checkout
+      - *attach_workspace
+      - run: node ./scripts/check-demo.js
+
 workflows:
   version: 2
   build_test:

package.json

@@ -136,6 +136,7 @@
     "eslint-plugin-react": "^7.14.2",
     "eslint-tinker": "^0.5.0",
     "fetch-jsonp": "^1.1.3",
+    "fs-extra": "^8.1.0",
     "full-icu": "^1.3.0",
     "glob": "^7.1.4",
     "husky": "^3.0.2",
@@ -186,7 +187,8 @@
     "stylelint-order": "^3.0.0",
     "typescript": "~3.5.1",
     "xhr-mock": "^2.4.1",
-    "xhr2": "^0.2.0"
+    "xhr2": "^0.2.0",
+    "yaml-front-matter": "^4.0.0"
   },
   "scripts": {
     "test": "jest --config .jest.js --no-cache",

scripts/check-demo.js

@@ -0,0 +1,14 @@
+const path = require('path');
+const yfm = require('yaml-front-matter');
+const glob = require('glob');
+const fs = require('fs-extra');
+
+const demoFiles = glob.sync(path.join(process.cwd(), 'components/**/demo/*.md'));
+// eslint-disable-next-line no-restricted-syntax
+for (const url of demoFiles) {
+  const demoContent = fs.readFileSync(url);
+  const meta = yfm.loadFront(demoContent);
+  if (meta.only) {
+    throw Error(`there is a 'only': ${url}`);
+  }
+}