Add support for the "module" package.json field

docs/Configuration.md

@@ -313,6 +313,13 @@ Default: `undefined`
 This option allows the use of a custom global teardown module which exports an
 async function that is triggered once after all test suites.
 
+### `module` [boolean]
+Default: `false`
+
+Respect the [`"module"` field](https://github.com/nodejs/node-eps/blob/master/002-es6-modules.md) in `package.json`. Many libraries that contain ES modules ([import/export syntax](http://www.2ality.com/2014/09/es6-modules-final.html)) use this field as a pointer to their untranspiled (ES6+) source, in addition to the ubiquitous `"main"` field that points to precompiled ES5 javascript.
+
+_TL;DR: enable this if your project uses import/export syntax._
+
 ### `moduleFileExtensions` [array<string>]
 
 Default: `["js", "json", "jsx", "node"]`

examples/module-field/.babelrc

@@ -0,0 +1,3 @@
+{
+  "presets": ["env"]
+}

examples/module-field/__tests__/index.js

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc. All rights reserved.
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+import { connect } from 'react-redux';
+import Contents from '../sample';
+
+describe('module field resolution', () => {
+  it('should return the correct file exports', () => {
+    expect(typeof connect).toBe('function');
+    expect(Contents).toBe('👏');
+  });
+});

examples/module-field/package.json

@@ -0,0 +1,16 @@
+{
+  "devDependencies": {
+    "babel-preset-env": "*",
+    "jest": "*"
+  },
+  "jest": {
+    "module": true
+  },
+  "scripts": {
+    "test": "jest"
+  },
+  "dependencies": {
+    "react-redux": "^5.0.6",
+    "redux": "^3.7.2"
+  }
+}

examples/module-field/sample/correct.js

@@ -0,0 +1,7 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc. All rights reserved.
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+export default '👏';

examples/module-field/sample/package.json

@@ -0,0 +1,4 @@
+{
+    "main": "wrong.js",
+    "module": "correct.js"
+}

examples/module-field/sample/wrong.js

@@ -0,0 +1,9 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc. All rights reserved.
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+module.exports = '😒';

packages/jest-config/src/defaults.js

@@ -46,6 +46,7 @@ export default ({
   haste: {
     providesModuleNodeModules: [],
   },
+  module: false,
   moduleDirectories: ['node_modules'],
   moduleFileExtensions: ['js', 'json', 'jsx', 'node'],
   moduleNameMapper: {},

packages/jest-config/src/index.js

@@ -154,6 +154,7 @@ const getConfigs = (
       forceCoverageMatch: options.forceCoverageMatch,
       globals: options.globals,
       haste: options.haste,
+      module: options.module,
       moduleDirectories: options.moduleDirectories,
       moduleFileExtensions: options.moduleFileExtensions,
       moduleLoader: options.moduleLoader,

packages/jest-config/src/normalize.js

@@ -496,6 +496,8 @@ export default function normalize(options: InitialOptions, argv: Argv) {
       case 'listTests':
       case 'logHeapUsage':
       case 'mapCoverage':
+      case 'module':
+      case 'moduleDirectories':
       case 'moduleFileExtensions':
       case 'name':
       case 'noStackTrace':

packages/jest-config/src/valid_config.js

@@ -49,6 +49,7 @@ export default ({
   json: false,
   lastCommit: false,
   logHeapUsage: true,
+  module: false,
   moduleDirectories: ['node_modules'],
   moduleFileExtensions: ['js', 'json', 'jsx', 'node'],
   moduleLoader: '<rootDir>',

packages/jest-resolve/src/default_resolver.js

@@ -15,6 +15,7 @@ type ResolverOptions = {|
   basedir: Path,
   browser?: boolean,
   extensions?: Array<string>,
+  module?: boolean,
   moduleDirectory?: Array<string>,
   paths?: ?Array<Path>,
   rootDir: ?Path,
@@ -29,6 +30,7 @@ export default function defaultResolver(
   return resolve(path, {
     basedir: options.basedir,
     extensions: options.extensions,
+    module: options.module,
     moduleDirectory: options.moduleDirectory,
     paths: options.paths,
     rootDir: options.rootDir,
@@ -47,6 +49,7 @@ import isBuiltinModule from './is_builtin_module';
 import nodeModulesPaths from './node_modules_paths';
 
 const REGEX_RELATIVE_IMPORT = /^(?:\.\.?(?:\/|$)|\/|([A-Za-z]:)?[\\\/])/;
+const REQUIRED_BY_MODULE_FIELD_CACHE = {};
 
 function resolveSync(target: Path, options: ResolverOptions): Path {
   const basedir = options.basedir;
@@ -122,15 +125,25 @@ function resolveSync(target: Path, options: ResolverOptions): Path {
       return undefined;
     }
 
-    const pkgfile = path.join(name, 'package.json');
-    let pkgmain;
+    let pkgentry, isRequiredByModuleField;
     try {
-      const body = fs.readFileSync(pkgfile, 'utf8');
-      pkgmain = JSON.parse(body).main;
+      const pkgfile = getPackageFile(name);
+
+      if (hasModuleField(pkgfile)) {
+        isRequiredByModuleField = true;
+        pkgentry = pkgfile.module;
+      } else {
+        pkgentry = pkgfile.main;
+      }
     } catch (e) {}
 
-    if (pkgmain && pkgmain !== '.') {
-      const resolveTarget = path.resolve(name, pkgmain);
+    if (pkgentry && pkgentry !== '.') {
+      const resolveTarget = path.resolve(name, pkgentry);
+
+      if (isRequiredByModuleField) {
+        REQUIRED_BY_MODULE_FIELD_CACHE[name] = true;
+      }
+
       const result = tryResolve(resolveTarget);
       if (result) {
         return result;
@@ -141,6 +154,21 @@ function resolveSync(target: Path, options: ResolverOptions): Path {
   }
 }
 
+function hasModuleField(pkgfile: string): boolean {
+  return !!pkgfile.module;
+}
+
+function getPackageFile(file: Path): string {
+  const pkgfile = path.join(file, 'package.json');
+
+  return JSON.parse(fs.readFileSync(pkgfile, 'utf8'));
+}
+
+export function couldBeRequiredByModuleField(file: Path): boolean {
+  return !!Object.keys(REQUIRED_BY_MODULE_FIELD_CACHE)
+    .find(moduleFieldCache => file.startsWith(moduleFieldCache));
+}
+
 /*
  * helper functions
  */

packages/jest-resolve/src/index.js

@@ -15,14 +15,15 @@ import fs from 'fs';
 import path from 'path';
 import nodeModulesPaths from './node_modules_paths';
 import isBuiltinModule from './is_builtin_module';
-import defaultResolver from './default_resolver.js';
+import defaultResolver, {couldBeRequiredByModuleField} from './default_resolver.js';
 import chalk from 'chalk';
 
 type ResolverConfig = {|
   browser?: boolean,
   defaultPlatform: ?string,
   extensions: Array<string>,
   hasCoreModules: boolean,
+  module?: boolean,
   moduleDirectories: Array<string>,
   moduleNameMapper: ?Array<ModuleNameMapperConfig>,
   modulePaths: Array<Path>,
@@ -35,6 +36,7 @@ type FindNodeModuleConfig = {|
   basedir: Path,
   browser?: boolean,
   extensions?: Array<string>,
+  module?: boolean,
   moduleDirectory?: Array<string>,
   paths?: Array<Path>,
   resolver?: ?Path,
@@ -74,6 +76,7 @@ class Resolver {
       extensions: options.extensions,
       hasCoreModules:
         options.hasCoreModules === undefined ? true : options.hasCoreModules,
+      module: options.module,
       moduleDirectories: options.moduleDirectories || ['node_modules'],
       moduleNameMapper: options.moduleNameMapper,
       modulePaths: options.modulePaths,
@@ -99,6 +102,7 @@ class Resolver {
         basedir: options.basedir,
         browser: options.browser,
         extensions: options.extensions,
+        module: options.module,
         moduleDirectory: options.moduleDirectory,
         paths: paths ? (nodePaths || []).concat(paths) : nodePaths,
         rootDir: options.rootDir,
@@ -107,6 +111,10 @@ class Resolver {
     return null;
   }
 
+  isRequiredByModuleField(path: Path): boolean {
+    return this._options.module && couldBeRequiredByModuleField(path);
+  }
+
   resolveModule(
     from: Path,
     moduleName: string,
@@ -155,6 +163,7 @@ class Resolver {
         basedir: dirname,
         browser: this._options.browser,
         extensions,
+        module: this._options.module,
         moduleDirectory,
         paths,
         resolver: this._options.resolver,
@@ -344,6 +353,7 @@ class Resolver {
               basedir: dirname,
               browser: this._options.browser,
               extensions,
+              module: this._options.module,
               moduleDirectory,
               paths,
               resolver,

packages/jest-runtime/src/index.js

@@ -249,6 +249,7 @@ class Runtime {
       defaultPlatform: config.haste.defaultPlatform,
       extensions: config.moduleFileExtensions.map(extension => '.' + extension),
       hasCoreModules: true,
+      module: config.module,
       moduleDirectories: config.moduleDirectories,
       moduleNameMapper: getModuleNameMapper(config),
       modulePaths: config.modulePaths,
@@ -501,6 +502,7 @@ class Runtime {
     this._currentlyExecutingModulePath = filename;
     const origCurrExecutingManualMock = this._isCurrentlyExecutingManualMock;
     this._isCurrentlyExecutingManualMock = filename;
+    const isRequiredByModuleField = this._config.module && this._resolver.isRequiredByModuleField(filename);
 
     const dirname = path.dirname(filename);
     localModule.children = [];

packages/jest-runtime/src/script_transformer.js

@@ -177,7 +177,7 @@ export default class ScriptTransformer {
     }
   }
 
-  transformSource(filepath: Path, content: string, instrument: boolean) {
+  transformSource(filepath: Path, content: string, instrument: boolean, isRequiredByModuleField: boolean) {
     const filename = this._getRealPath(filepath);
     const transform = this._getTransformer(filename);
     const cacheFilePath = this._getFileCachePath(filename, content, instrument);
@@ -214,7 +214,7 @@ export default class ScriptTransformer {
       map: null,
     };
 
-    if (transform && shouldCallTransform) {
+    if (isRequiredByModuleField || (transform && shouldCallTransform)) {
       const processed = transform.process(content, filename, this._config, {
         instrument,
         returnSourceString: false,
@@ -283,16 +283,21 @@ export default class ScriptTransformer {
     let mapCoverage = false;
 
     const willTransform =
-      !isInternalModule &&
-      !isCoreModule &&
-      (shouldTransform(filename, this._config) || instrument);
+      options.isRequiredByModuleField ||
+      (
+        !isInternalModule &&
+        !isCoreModule &&
+        (shouldTransform(filename, this._config) || instrument)
+      );
 
     try {
       if (willTransform) {
         const transformedSource = this.transformSource(
           filename,
           content,
           instrument,
+          options.isRequiredByModuleField,
+          !!(options && options.mapCoverage),
         );
 
         wrappedCode = wrap(transformedSource.code);

types/Config.js

@@ -31,13 +31,14 @@ export type DefaultOptions = {|
   clearMocks: boolean,
   coveragePathIgnorePatterns: Array<string>,
   coverageReporters: Array<string>,
+  detectLeaks: boolean,
   expand: boolean,
   forceCoverageMatch: Array<Glob>,
   globals: ConfigGlobals,
   globalSetup: ?string,
   globalTeardown: ?string,
   haste: HasteConfig,
-  detectLeaks: boolean,
+  module: boolean,
   moduleDirectories: Array<string>,
   moduleFileExtensions: Array<string>,
   moduleNameMapper: {[key: string]: string},
@@ -98,10 +99,11 @@ export type InitialOptions = {
   globalTeardown?: ?string,
   haste?: HasteConfig,
   reporters?: Array<ReporterConfig | string>,
-  logHeapUsage?: boolean,
   lastCommit?: boolean,
+  logHeapUsage?: boolean,
   listTests?: boolean,
   mapCoverage?: boolean,
+  module?: boolean,
   moduleDirectories?: Array<string>,
   moduleFileExtensions?: Array<string>,
   moduleLoader?: Path,
@@ -224,6 +226,7 @@ export type ProjectConfig = {|
   forceCoverageMatch: Array<Glob>,
   globals: ConfigGlobals,
   haste: HasteConfig,
+  module?: boolean,
   moduleDirectories: Array<string>,
   moduleFileExtensions: Array<string>,
   moduleLoader: Path,