Improve React Native support without extra files

process-dir.js

@@ -7,7 +7,6 @@ let fs = require('fs')
 
 let writeFile = promisify(fs.writeFile)
 let readFile = promisify(fs.readFile)
-let unlink = promisify(fs.unlink)
 
 const NAME = /(^|\n)(let\s+|const\s+|var\s+)(\S+|{[^}]+})\s*=/m
 
@@ -106,23 +105,6 @@ async function replaceToESM (dir, file, source) {
   await writeFile(join(dir, file), esm)
 }
 
-async function replaceToNative (dir, file, source) {
-  let cjs = replaceRequire(
-    source,
-    exported => exported,
-    (named, prefix, varType, name) => {
-      let path = getPath(file, named, 'cjs')
-      return `${ prefix }${ varType }${ name } = require(${ path })`
-    },
-    (nameless, prefix) => {
-      let path = getPath(file, nameless, 'cjs')
-      return `${ prefix }require(${ path })`
-    }
-  )
-  await writeFile(join(dir, file.replace(/\.native\.js$/, '.cjs$&')), cjs)
-  await unlink(join(dir, file))
-}
-
 async function replaceToCJS (dir, file, source) {
   let cjs = replaceRequire(
     source,
@@ -136,10 +118,7 @@ async function replaceToCJS (dir, file, source) {
       return `${ prefix }require(${ path })`
     }
   )
-  await Promise.all([
-    writeFile(join(dir, file.replace(/\.js$/, '.cjs')), cjs),
-    writeFile(join(dir, file.replace(/\.js$/, '.cjs.js')), cjs)
-  ])
+  await writeFile(join(dir, file.replace(/\.js$/, '.cjs')), cjs)
 }
 
 async function replacePackage (dir, file, files) {
@@ -151,6 +130,8 @@ async function replacePackage (dir, file, files) {
   pkg.type = 'module'
   pkg.main = 'index.cjs'
   pkg.module = 'index.js'
+  pkg['react-native'] = 'index.js'
+
   if (file === 'index.js') {
     pkg.exports = { }
     for (let i of files) {
@@ -166,11 +147,19 @@ async function replacePackage (dir, file, files) {
         pkg.exports[path].browser = path + '/index.browser.js'
       }
     }
-  } else if (files.includes(file.replace(/\.js$/, '.browser.js'))) {
+  }
+
+  if (files.includes(file.replace(/\.js$/, '.browser.js'))) {
     pkg.browser = {
       './index.js': './index.browser.js'
     }
   }
+  if (files.includes(file.replace(/\.js$/, '.native.js'))) {
+    pkg['react-native'] = {
+      './index.js': './index.native.js'
+    }
+  }
+
   await writeFile(pkgFile, JSON.stringify(pkg, null, 2))
 }
 
@@ -209,7 +198,7 @@ async function process (dir) {
     if (file.endsWith('index.browser.js')) {
       await replaceToESM(dir, file, source)
     } else if (file.endsWith('index.native.js')) {
-      await replaceToNative(dir, file, source)
+      await replaceToESM(dir, file, source)
     } else {
       await Promise.all([
         replaceToCJS(dir, file, source),

test/fixtures/rn-lib/a/index.js

@@ -0,0 +1,9 @@
+let { b } = require('../b')
+require('../c')
+
+let a = () => {
+  b()
+  console.log('cjs a')
+}
+
+module.exports = { a }

test/fixtures/rn-lib/a/index.native.js

@@ -1,7 +1,7 @@
-let b = require('../b')
+let { b } = require('../b')
 require('../c')
 
-a = () => {
+let a = () => {
   b()
   console.log('native a')
 }

test/fixtures/rn-lib/b/index.js

@@ -1,4 +1,4 @@
-b = () => {
+let b = () => {
   console.log('cjs b')
 }
 

test/index.test.js

@@ -160,9 +160,8 @@ it('compiles for React Native', async () => {
   await replaceConsole(lib)
   await exec(`yarn add rn-lib@${ lib }`, { cwd: runner })
 
-  let cfg = await metro.loadConfig()
-  cfg = {
-    ...cfg,
+  let config = {
+    ...await metro.loadConfig(),
     projectRoot: runner,
     watchFolders: [
       runner,
@@ -171,18 +170,21 @@ it('compiles for React Native', async () => {
     reporter: { update: () => {} },
     cacheStores: [],
     resetCache: true,
+    resolver: {
+      resolverMainFields: ['react-native', 'browser', 'main']
+    },
     transformer: {
       babelTransformerPath: 'metro-react-native-babel-transformer'
     }
   }
-  let { code } = await metro.runBuild(cfg, {
+  let { code } = await metro.runBuild(config, {
     entry: 'index.js',
     minify: false,
     sourceMap: false
   })
   expect(code).toContain('console.log(\'native a\')')
-  expect(code).toContain('console.log(\'cjs b\')')
-  expect(code).toContain('console.log(\'cjs c\')')
+  expect(code).toContain('console.log(\'esm b\')')
+  expect(code).toContain('console.log(\'esm c\')')
 })
 
 it('works with require in webpack', async () => {