add prettier check in ci (#23382)

Summary:
enforce code format
Pull Request resolved: https://github.com/facebook/react-native/pull/23382

Differential Revision: D14024609

Pulled By: cpojer

fbshipit-source-id: 21176cf8f009987e5a281bbead414374632eabee

.circleci/config.yml

@@ -358,6 +358,7 @@ jobs:
       - run: *setup-artifacts
       - run: *yarn
       - run: *run-js-tests
+      - run: yarn run format-check
       - store_test_results:
           path: ~/react-native/reports/junit
 

Libraries/vendor/core/Map.js

@@ -546,8 +546,10 @@ module.exports = (function(global, undefined) {
       }
 
       if (!isES5) {
-        if (hasOwn.call(o, "propertyIsEnumerable") &&
-            hasOwn.call(o.propertyIsEnumerable, hashProperty)) {
+        if (
+          hasOwn.call(o, 'propertyIsEnumerable') &&
+          hasOwn.call(o.propertyIsEnumerable, hashProperty)
+        ) {
           return o.propertyIsEnumerable[hashProperty];
         }
       }
@@ -571,7 +573,7 @@ module.exports = (function(global, undefined) {
           o.propertyIsEnumerable = function() {
             return propIsEnumerable.apply(this, arguments);
           };
-          return o.propertyIsEnumerable[hashProperty] = ++hashCounter;
+          return (o.propertyIsEnumerable[hashProperty] = ++hashCounter);
         }
       }
 

Libraries/vendor/core/_wrapObjectFreezeAndFriends.js

@@ -19,13 +19,15 @@ function getTestMap() {
 // Wrap Object.{freeze,seal,preventExtensions} so each function adds its
 // argument to a Map first, which gives our ./Map.js polyfill a chance to
 // tag the object before it becomes non-extensible.
-["freeze", "seal", "preventExtensions"].forEach(name => {
+['freeze', 'seal', 'preventExtensions'].forEach(name => {
   const method = Object[name];
-  if (typeof method === "function") {
-    (Object: any)[name] = function (obj) {
+  if (typeof method === 'function') {
+    (Object: any)[name] = function(obj) {
       try {
         // If .set succeeds, also call .delete to avoid leaking memory.
-        getTestMap().set(obj, obj).delete(obj);
+        getTestMap()
+          .set(obj, obj)
+          .delete(obj);
       } finally {
         // If .set fails, the exception will be silently swallowed
         // by this return-from-finally statement, and the method will

package.json

@@ -139,7 +139,8 @@
     "flow-check-ios": "flow check",
     "flow-check-android": "flow check --flowconfig-name .flowconfig.android",
     "lint": "eslint .",
-    "prettier": "prettier \"./**/*.js\" --write",
+    "prettier": "prettier --write \"./**/*.js\" \"./**/*.md\"",
+    "format-check": "prettier --list-different \"./**/*.js\" \"./**/*.md\"",
     "docker-setup-android": "docker pull reactnativecommunity/react-native-android",
     "docker-build-android": "docker build -t reactnativeci/android -f ContainerShip/Dockerfile.android .",
     "test-android-run-instrumentation": "docker run --cap-add=SYS_ADMIN -it reactnativeci/android bash ContainerShip/scripts/run-android-docker-instrumentation-tests.sh",