jest: Use babel-jest instead of a custom implementation

packages/jest/package.json

@@ -22,14 +22,11 @@
     "yarn": ">=1.2.1"
   },
   "dependencies": {
-    "@babel/core": "^7.1.2",
-    "@babel/plugin-transform-modules-commonjs": "^7.1.0",
-    "@neutrinojs/compile-loader": "9.0.0-0",
     "@neutrinojs/loader-merge": "9.0.0-0",
-    "babel-plugin-jest-hoist": "^23.2.0",
+    "babel-core": "^7.0.0-bridge",
+    "babel-jest": "^23.6.0",
     "deepmerge": "^1.5.2",
-    "eslint-plugin-jest": "^21.25.0",
-    "lodash.omit": "^4.5.0"
+    "eslint-plugin-jest": "^21.25.0"
   },
   "peerDependencies": {
     "jest": "^23.0.0",

packages/jest/src/index.js

@@ -1,7 +1,5 @@
 const loaderMerge = require('@neutrinojs/loader-merge');
-const compileLoader = require('@neutrinojs/compile-loader');
 const merge = require('deepmerge');
-const omit = require('lodash.omit');
 const { basename, isAbsolute, join, relative } = require('path');
 const { media, style } = require('neutrino/extensions');
 
@@ -20,43 +18,12 @@ module.exports = (neutrino, options = {}) => {
   });
 
   neutrino.register('jest', (neutrino) => {
-    const usingBabel = neutrino.config.module.rules.has('compile');
+    const compileRule = neutrino.config.module.rules.get('compile');
+    const babelOptions = compileRule ? compileRule.use('babel').get('options') : {};
+    // Any parts of the babel config that are not serializable will be omitted, however
+    // that also occurs when passing to the custom transformer using `globals` instead.
+    process.env.JEST_BABEL_OPTIONS = JSON.stringify(babelOptions);
 
-    if (usingBabel) {
-      neutrino.config.module
-        .rule('compile')
-        .use('babel')
-        .tap(options => compileLoader.merge(options, {
-          plugins: [
-            // Once babel-preset-jest has better Babel 7 support we should
-            // switch back to it (or even use babel-jest, which will allow
-            // simplifying the transformer too):
-            // https://github.com/facebook/jest/issues/6126
-            // For now this plugin is taken from here (we don't need
-            // object-rest-spread since node >=8.3):
-            // https://github.com/facebook/jest/blob/v22.4.2/packages/babel-preset-jest/index.js#L11-L12
-            require.resolve('babel-plugin-jest-hoist'),
-            // Since the tests will be run by node which doesn't yet support
-            // ES2015 modules
-            require.resolve('@babel/plugin-transform-modules-commonjs')
-          ]
-        }));
-    }
-
-    const babelOptions = usingBabel
-      ? compileLoader.merge(
-        omit(
-          neutrino.config.module.rule('compile').use('babel').get('options'),
-          ['cacheDirectory']
-        ),
-        {
-          retainLines: true,
-          plugins: [
-            require.resolve('@babel/plugin-transform-modules-commonjs')
-          ]
-        }
-      )
-      : {};
     const getFinalPath = path => {
       if (isAbsolute(path)) {
         return path;
@@ -109,9 +76,6 @@ module.exports = (neutrino, options = {}) => {
         // property name where a Regex object will cause issues. e.g.:
         // https://github.com/neutrinojs/neutrino/issues/638.
         [extensionsToNames(extensions)]: require.resolve('./transformer')
-      },
-      globals: {
-        BABEL_OPTIONS: babelOptions
       }
     }, options);
   });

packages/jest/src/transformer.js

@@ -1,13 +1,5 @@
-const { transform } = require('@babel/core');
+const { createTransformer } = require('babel-jest');
 
-module.exports = {
-  // This is inspired by:
-  // https://github.com/facebook/jest/blob/v22.4.2/packages/babel-jest/src/index.js#L105-L147
-  // And is required due to:
-  // https://github.com/facebook/jest/issues/1468
-  // TODO: See if it would be easier to wrap the higher-level babel-jest instead.
-  process(src, filename, config) {
-    // Babel 7 returns null if the file was ignored.
-    return transform(src, { filename, ...config.globals.BABEL_OPTIONS }) || src;
-  }
-};
+const babelOptions = JSON.parse(process.env.JEST_BABEL_OPTIONS);
+
+module.exports = createTransformer(babelOptions);

yarn.lock

@@ -1536,6 +1536,11 @@ babel-core@^6.0.0, babel-core@^6.26.0:
     slash "^1.0.0"
     source-map "^0.5.7"
 
+babel-core@^7.0.0-bridge:
+  version "7.0.0-bridge.0"
+  resolved "https://registry.yarnpkg.com/babel-core/-/babel-core-7.0.0-bridge.0.tgz#95a492ddd90f9b4e9a4a1da14eb335b87b634ece"
+  integrity sha512-poPX9mZH/5CSanm50Q+1toVci6pv5KSRv/5TWCwtzQS5XEwn40BcCrgIeMFWP9CKKIniKXNxoIOnOq4VVlGXhg==
+
 babel-eslint@^10.0.1:
   version "10.0.1"
   resolved "https://registry.yarnpkg.com/babel-eslint/-/babel-eslint-10.0.1.tgz#919681dc099614cd7d31d45c8908695092a1faed"