Plug'n'Play support (facebook#5136)

* Adds the PnP plugin for Webpack to find dependencies when working under PnP

* Adds configuration for jest

* Adds an e2e test for when using PnP

* Avoids cra from crashing at the engine check

* Avoids cra from crashing when initializing react-scripts

* Makes the ownPath portable

* Fixes linting

* Bumps to pnp-webpack-plugin@1.1.0, removes symlinks: false

* Adds a --use-pnp option

* Pin version

config/webpack.config.dev.js

@@ -10,6 +10,7 @@
 
 const path = require('path');
 const webpack = require('webpack');
+const PnpWebpackPlugin = require('pnp-webpack-plugin');
 const HtmlWebpackPlugin = require('html-webpack-plugin');
 const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
 const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
@@ -150,6 +151,9 @@ module.exports = {
       'react-native': 'react-native-web',
     },
     plugins: [
+      // Adds support for installing with Plug'n'Play, leading to faster installs and adding
+      // guards against forgotten dependencies and such.
+      PnpWebpackPlugin,
       // Prevents users from importing files from outside of src/ (or node_modules/).
       // This often causes confusion because we only process files within src/ with babel.
       // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
@@ -158,6 +162,13 @@ module.exports = {
       new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
     ],
   },
+  resolveLoader: {
+    plugins: [
+      // Also related to Plug'n'Play, but this time it tells Webpack to load its loaders
+      // from the current package.
+      PnpWebpackPlugin.moduleLoader(module),
+    ],
+  },
   module: {
     strictExportPresence: true,
     rules: [

config/webpack.config.prod.js

@@ -10,6 +10,7 @@
 
 const path = require('path');
 const webpack = require('webpack');
+const PnpWebpackPlugin = require('pnp-webpack-plugin');
 const HtmlWebpackPlugin = require('html-webpack-plugin');
 const InlineChunkHtmlPlugin = require('react-dev-utils/InlineChunkHtmlPlugin');
 const TerserPlugin = require('terser-webpack-plugin');
@@ -214,6 +215,9 @@ module.exports = {
       'react-native': 'react-native-web',
     },
     plugins: [
+      // Adds support for installing with Plug'n'Play, leading to faster installs and adding
+      // guards against forgotten dependencies and such.
+      PnpWebpackPlugin,
       // Prevents users from importing files from outside of src/ (or node_modules/).
       // This often causes confusion because we only process files within src/ with babel.
       // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
@@ -222,6 +226,13 @@ module.exports = {
       new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
     ],
   },
+  resolveLoader: {
+    plugins: [
+      // Also related to Plug'n'Play, but this time it tells Webpack to load its loaders
+      // from the current package.
+      PnpWebpackPlugin.moduleLoader(module),
+    ],
+  },
   module: {
     strictExportPresence: true,
     rules: [

package.json

@@ -47,8 +47,11 @@
     "html-webpack-plugin": "4.0.0-alpha.2",
     "identity-obj-proxy": "3.0.0",
     "jest": "23.6.0",
+    "jest-pnp-resolver": "1.0.1",
+    "jest-resolve": "23.6.0",
     "mini-css-extract-plugin": "0.4.3",
     "optimize-css-assets-webpack-plugin": "5.0.1",
+    "pnp-webpack-plugin": "1.1.0",
     "postcss-flexbugs-fixes": "4.1.0",
     "postcss-loader": "3.0.0",
     "postcss-preset-env": "6.0.6",

scripts/init.js

@@ -81,9 +81,9 @@ module.exports = function(
   originalDirectory,
   template
 ) {
-  const ownPackageName = require(path.join(__dirname, '..', 'package.json'))
-    .name;
-  const ownPath = path.join(appPath, 'node_modules', ownPackageName);
+  const ownPath = path.dirname(
+    require.resolve(path.join(__dirname, '..', 'package.json'))
+  );
   const appPackage = require(path.join(appPath, 'package.json'));
   const useYarn = fs.existsSync(path.join(appPath, 'yarn.lock'));
 

scripts/utils/createJestConfig.js

@@ -22,7 +22,8 @@ module.exports = (resolve, rootDir, isEjecting) => {
   // in Jest configs. We need help from somebody with Windows to determine this.
   const config = {
     collectCoverageFrom: ['src/**/*.{js,jsx}'],
-    setupFiles: ['react-app-polyfill/jsdom'],
+    resolver: require.resolve('jest-pnp-resolver'),
+    setupFiles: [require.resolve('react-app-polyfill/jsdom')],
     setupTestFrameworkScriptFile: setupTestsFile,
     testMatch: [
       '<rootDir>/src/**/__tests__/**/*.{js,jsx}',