Export the hmr plugin directly

Summary: This will allow to configure the HMR plugin directly from `.babelrc` again, instead of having to create a bridge file: https://github.com/rafeca/metro-sample-app/blob/master/metro-babel7-plugin-react-transform.js#L3

Reviewed By: davidaurelio

Differential Revision: D7707314

fbshipit-source-id: 4c5612e1e5d27874807f2dce50d99ec0f6354bbc

packages/metro-babel7-plugin-react-transform/__tests__/babel-plugin-react-transform-test.js

@@ -18,7 +18,7 @@ const path = require('path');
 
 /*eslint-disable import/no-extraneous-dependencies*/
 const {transformSync} = require('@babel/core');
-const reactPlugin = require('../lib/index.js').default;
+const reactPlugin = require('../lib/index.js');
 
 describe('finds React components', () => {
   const fixturesDir = path.join(__dirname, '__fixtures__');

packages/metro-babel7-plugin-react-transform/lib/index.js

@@ -28,8 +28,7 @@ const find = require('lodash/find');
 
 const {addDefault} = require('@babel/helper-module-imports');
 
-module.exports = {
-  default: function({types: t, template}) {
+module.exports = function({types: t, template}) {
   function matchesPatterns(path, patterns) {
     return !!find(patterns, pattern => {
       return (
@@ -115,8 +114,7 @@ module.exports = {
       path.node[VISITED_KEY] = true;
 
       const componentName = (path.node.id && path.node.id.name) || null;
-        const componentId =
-          componentName || path.scope.generateUid('component');
+      const componentId = componentName || path.scope.generateUid('component');
       const isInFunction = hasParentFunction(path);
 
       this.components.push({
@@ -189,8 +187,7 @@ module.exports = {
 
       // `foo({ displayName: 'NAME' });` => 'NAME'
       const componentName = getDisplayName(path.node);
-        const componentId =
-          componentName || path.scope.generateUid('component');
+      const componentId = componentName || path.scope.generateUid('component');
       const isInFunction = hasParentFunction(path);
 
       this.components.push({
@@ -338,10 +335,7 @@ module.exports = {
           objectKey = t.stringLiteral(componentId);
         }
 
-          return t.objectProperty(
-            objectKey,
-            t.objectExpression(componentProps),
-          );
+        return t.objectProperty(objectKey, t.objectExpression(componentProps));
       });
 
       return t.variableDeclaration('const', [
@@ -385,9 +379,7 @@ module.exports = {
             configuredTransformId,
             t.callExpression(transformImportId, [
               toObjectExpression({
-                  filename: t.stringLiteral(
-                    this.file.opts.filename || 'unknown',
-                  ),
+                filename: t.stringLiteral(this.file.opts.filename || 'unknown'),
                 components: componentsDeclarationId,
                 locals: t.arrayExpression(transformLocals),
                 imports: t.arrayExpression(transformImports),
@@ -437,5 +429,4 @@ module.exports = {
       },
     },
   };
-  },
 };

packages/metro/src/babel-bridge.js

@@ -135,7 +135,7 @@ function makeMakeHMRConfig7() {
     return {
       plugins: [
         [
-          require('metro-babel7-plugin-react-transform').default,
+          require('metro-babel7-plugin-react-transform'),
           {
             transforms: [
               {