fix support for node 8

babel.config.js

@@ -33,7 +33,7 @@ module.exports = {
           },
         ],
       ],
-      test: 'packages/jest-config/src/readConfigFileAndSetRootDir.ts',
+      test: 'packages/jest-config/src/importMjs.ts',
     },
   ],
   plugins: [

packages/jest-config/src/importMjs.ts

@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// this is in a separate file so that node 8 don't explode with a syntax error.
+// Remove this file when we drop support for Node 8
+export default (specifier: string) => import(specifier);

packages/jest-config/src/readConfigFileAndSetRootDir.ts

@@ -15,6 +15,7 @@ import {
   JEST_CONFIG_EXT_MJS,
   PACKAGE_JSON,
 } from './constants';
+import importMjs from './importMjs';
 
 // Read the configuration and set its `rootDir`
 // 1. If it's a `package.json` file, we look into its "jest" property
@@ -28,7 +29,7 @@ export default async function readConfigFileAndSetRootDir(
 
   if (isMjs) {
     try {
-      const importedConfig = await import(configPath);
+      const importedConfig = await importMjs(configPath);
 
       if (!importedConfig.default) {
         throw new Error(

scripts/build.js

@@ -149,7 +149,14 @@ function buildFile(file, silent) {
           Array.isArray(plugin) &&
           plugin[0] === '@babel/plugin-transform-modules-commonjs'
         ) {
-          return [plugin[0], Object.assign({}, plugin[1], {lazy: true})];
+          return [
+            plugin[0],
+            Object.assign({}, plugin[1], {
+              lazy: string =>
+                // we want to lazyload all non-local modules plus `importMjs` - the latter to avoid syntax errors. Set to just `true` when we drop support for node 8
+                !string.startsWith('./') || string === './importMjs',
+            }),
+          ];
         }
 
         return plugin;