feat: pass conditions when resolving modules

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Features
 
+- `[jest-resolver, jest-runtime]` Pass `conditions` to custom resolvers to enable them to implement support for package.json `exports` field ([#11859](https://github.com/facebook/jest/pull/11859))
+
 ### Fixes
 
 - `[@jest/reporters]` Use async transform if available to transform files with no coverage ([#11852](https://github.com/facebook/jest/pull/11852))

docs/Configuration.md

@@ -788,11 +788,13 @@ This option allows the use of a custom resolver. This resolver must be a node mo
 ```json
 {
   "basedir": string,
+  "conditions": [string],
   "defaultResolver": "function(request, options)",
   "extensions": [string],
   "moduleDirectory": [string],
   "paths": [string],
   "packageFilter": "function(pkg, pkgdir)",
+  "pathFilter": "function(pkg, path, relativePath)",
   "rootDir": [string]
 }
 ```
@@ -849,6 +851,8 @@ module.exports = (request, options) => {
 };
 ```
 
+While Jest does not support [package `exports`](https://nodejs.org/api/packages.html#packages_package_entry_points) (beyond `main`), Jest will provide `conditions` as an option when calling custom resolvers, which can be used to implement support for `exports` in userland. Jest will pass `['import', 'default']` when running a test in ESM mode, and `['require', 'default']` when running with CJS.
+
 ### `restoreMocks` \[boolean]
 
 Default: `false`

e2e/__tests__/__snapshots__/moduleNameMapper.test.ts.snap

@@ -41,7 +41,7 @@ FAIL __tests__/index.js
       12 | module.exports = () => 'test';
       13 |
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:566:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:577:17)
       at Object.require (index.js:10:1)
 `;
 
@@ -70,6 +70,6 @@ FAIL __tests__/index.js
       12 | module.exports = () => 'test';
       13 |
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:566:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:577:17)
       at Object.require (index.js:10:1)
 `;

e2e/__tests__/__snapshots__/resolveNoFileExtensions.test.ts.snap

@@ -37,6 +37,6 @@ FAIL __tests__/test.js
         |                  ^
       9 |
 
-      at Resolver.resolveModule (../../packages/jest-resolve/build/resolver.js:318:11)
+      at Resolver.resolveModule (../../packages/jest-resolve/build/resolver.js:322:11)
       at Object.require (index.js:8:18)
 `;

e2e/__tests__/resolveConditions.test.ts

@@ -0,0 +1,35 @@
+/**
+ * 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.
+ */
+
+import {resolve} from 'path';
+import {onNodeVersions} from '@jest/test-utils';
+import {runYarnInstall} from '../Utils';
+import runJest from '../runJest';
+
+const dir = resolve(__dirname, '..', 'resolve-conditions');
+
+beforeAll(() => {
+  runYarnInstall(dir);
+});
+
+// The versions where vm.Module exists and commonjs with "exports" is not broken
+onNodeVersions('^12.16.0 || >=13.7.0', () => {
+  test('resolves package exports correctly with custom resolver', () => {
+    // run multiple times to ensure there are no caching errors
+    for (let i = 0; i < 5; i++) {
+      const {exitCode} = runJest(dir, [], {
+        nodeOptions: '--experimental-vm-modules',
+      });
+      try {
+        expect(exitCode).toBe(0);
+      } catch (error) {
+        console.log(`Test failed on iteration ${i + 1}`);
+        throw error;
+      }
+    }
+  });
+});

e2e/resolve-conditions/__tests__/resolveCjs.test.cjs

@@ -0,0 +1,12 @@
+/**
+ * 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.
+ */
+
+const {fn} = require('../fake-dep');
+
+test('returns correct message', () => {
+  expect(fn()).toEqual('hello from CJS');
+});

e2e/resolve-conditions/__tests__/resolveEsm.test.mjs

@@ -0,0 +1,12 @@
+/**
+ * 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.
+ */
+
+import {fn} from '../fake-dep';
+
+test('returns correct message', () => {
+  expect(fn()).toEqual('hello from ESM');
+});

e2e/resolve-conditions/fake-dep/module.cjs

@@ -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.
+ */
+
+module.exports = {
+  fn: () => 'hello from CJS',
+};

e2e/resolve-conditions/fake-dep/module.mjs

@@ -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.
+ */
+
+export function fn() {
+  return 'hello from ESM';
+}

e2e/resolve-conditions/fake-dep/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "fake-dep",
+  "version": "1.0.0",
+  "exports": {
+    ".": {
+      "import": "./module.mjs",
+      "require": "./module.cjs"
+    }
+  }
+}

e2e/resolve-conditions/package.json

@@ -0,0 +1,18 @@
+{
+  "jest": {
+    "moduleFileExtensions": [
+      "js",
+      "cjs",
+      "mjs",
+      "json"
+    ],
+    "resolver": "<rootDir>/resolver.js",
+    "testMatch": [
+      "<rootDir>/**/*.test.*"
+    ],
+    "transform": {}
+  },
+  "dependencies": {
+    "resolve.exports": "^1.0.2"
+  }
+}

e2e/resolve-conditions/resolver.js

@@ -0,0 +1,34 @@
+/**
+ * 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.
+ */
+
+'use strict';
+
+const {resolve: resolveExports} = require('resolve.exports');
+
+module.exports = (path, options) => {
+  return options.defaultResolver(path, {
+    ...options,
+    pathFilter: options.conditions
+      ? createPathFilter(options.conditions)
+      : undefined,
+  });
+};
+
+function createPathFilter(conditions) {
+  return function pathFilter(pkg, _path, relativePath) {
+    // this `index` thing can backfire, but `resolve` adds it: https://github.com/browserify/resolve/blob/f1b51848ecb7f56f77bfb823511d032489a13eab/lib/sync.js#L192
+    const path = relativePath === 'index' ? '.' : relativePath;
+
+    return (
+      resolveExports(pkg, path, {
+        conditions,
+        // `resolve.exports adds `import` unless `require` is `false`, so let's add this ugly thing
+        require: !conditions.includes('import'),
+      }) || relativePath
+    );
+  };
+}

e2e/resolve-conditions/yarn.lock

@@ -0,0 +1,21 @@
+# This file is generated by running "yarn install" inside your project.
+# Manual changes might be lost - proceed with caution!
+
+__metadata:
+  version: 4
+  cacheKey: 7
+
+"resolve.exports@npm:^1.0.2":
+  version: 1.0.2
+  resolution: "resolve.exports@npm:1.0.2"
+  checksum: 012a46e3ae41c53762abf5b50ea1b4adf2de617bbea1dbc7bf6e609c1ceaedee7782acbc92d443951d5dd0c3a8fb1090ce73285a9ccc24b530e33b5e09ae196f
+  languageName: node
+  linkType: hard
+
+"root-workspace-0b6124@workspace:.":
+  version: 0.0.0-use.local
+  resolution: "root-workspace-0b6124@workspace:."
+  dependencies:
+    resolve.exports: ^1.0.2
+  languageName: unknown
+  linkType: soft

packages/jest-resolve/src/__tests__/resolve.test.ts

@@ -105,6 +105,7 @@ describe('findNodeModule', () => {
     const newPath = Resolver.findNodeModule('test', {
       basedir: '/',
       browser: true,
+      conditions: ['conditions, woooo'],
       extensions: ['js'],
       moduleDirectory: ['node_modules'],
       paths: ['/something'],
@@ -116,6 +117,7 @@ describe('findNodeModule', () => {
     expect(userResolver.mock.calls[0][1]).toStrictEqual({
       basedir: '/',
       browser: true,
+      conditions: ['conditions, woooo'],
       defaultResolver,
       extensions: ['js'],
       moduleDirectory: ['node_modules'],

packages/jest-resolve/src/defaultResolver.ts

@@ -19,7 +19,16 @@ type ResolverOptions = {
   moduleDirectory?: Array<string>;
   paths?: Array<Config.Path>;
   rootDir?: Config.Path;
-  packageFilter?: (pkg: any, pkgfile: string) => any;
+  packageFilter?: (
+    pkg: Record<string, unknown>,
+    pkgfile: string,
+  ) => Record<string, unknown>;
+  pathFilter?: (
+    pkg: Record<string, unknown>,
+    path: string,
+    relativePath: string,
+  ) => string;
+  conditions?: Array<string>;
 };
 
 // https://github.com/facebook/jest/pull/10617
@@ -48,6 +57,7 @@ export default function defaultResolver(
     isFile,
     moduleDirectory: options.moduleDirectory,
     packageFilter: options.packageFilter,
+    pathFilter: options.pathFilter,
     paths: options.paths,
     preserveSymlinks: false,
     readPackageSync,

packages/jest-resolve/src/resolver.ts

@@ -23,6 +23,7 @@ import type {ResolverConfig} from './types';
 type FindNodeModuleConfig = {
   basedir: Config.Path;
   browser?: boolean;
+  conditions?: Array<string>;
   extensions?: Array<string>;
   moduleDirectory?: Array<string>;
   paths?: Array<Config.Path>;
@@ -32,6 +33,7 @@ type FindNodeModuleConfig = {
 };
 
 export type ResolveModuleConfig = {
+  conditions?: Array<string>;
   skipNodeResolution?: boolean;
   paths?: Array<Config.Path>;
 };
@@ -113,6 +115,7 @@ export default class Resolver {
       return resolver(path, {
         basedir: options.basedir,
         browser: options.browser,
+        conditions: options.conditions,
         defaultResolver,
         extensions: options.extensions,
         moduleDirectory: options.moduleDirectory,
@@ -137,7 +140,8 @@ export default class Resolver {
   ): Config.Path | null {
     const paths = options?.paths || this._options.modulePaths;
     const moduleDirectory = this._options.moduleDirectories;
-    const key = dirname + path.delimiter + moduleName;
+    const stringifiedOptions = options ? JSON.stringify(options) : '';
+    const key = dirname + path.delimiter + moduleName + stringifiedOptions;
     const defaultPlatform = this._options.defaultPlatform;
     const extensions = this._options.extensions.slice();
     let module;
@@ -183,6 +187,7 @@ export default class Resolver {
 
       return Resolver.findNodeModule(name, {
         basedir: dirname,
+        conditions: options?.conditions,
         extensions,
         moduleDirectory,
         paths,
@@ -321,23 +326,31 @@ export default class Resolver {
     virtualMocks: Map<string, boolean>,
     from: Config.Path,
     moduleName = '',
+    options?: ResolveModuleConfig,
   ): string {
-    const key = from + path.delimiter + moduleName;
+    const stringifiedOptions = options ? JSON.stringify(options) : '';
+    const key = from + path.delimiter + moduleName + stringifiedOptions;
     const cachedModuleID = this._moduleIDCache.get(key);
     if (cachedModuleID) {
       return cachedModuleID;
     }
 
     const moduleType = this._getModuleType(moduleName);
-    const absolutePath = this._getAbsolutePath(virtualMocks, from, moduleName);
+    const absolutePath = this._getAbsolutePath(
+      virtualMocks,
+      from,
+      moduleName,
+      options,
+    );
     const mockPath = this._getMockPath(from, moduleName);
 
     const sep = path.delimiter;
     const id =
       moduleType +
       sep +
       (absolutePath ? absolutePath + sep : '') +
-      (mockPath ? mockPath + sep : '');
+      (mockPath ? mockPath + sep : '') +
+      (stringifiedOptions ? stringifiedOptions + sep : '');
 
     this._moduleIDCache.set(key, id);
     return id;
@@ -351,13 +364,14 @@ export default class Resolver {
     virtualMocks: Map<string, boolean>,
     from: Config.Path,
     moduleName: string,
+    options?: ResolveModuleConfig,
   ): Config.Path | null {
     if (this.isCoreModule(moduleName)) {
       return moduleName;
     }
     return this._isModuleResolved(from, moduleName)
       ? this.getModule(moduleName)
-      : this._getVirtualMockPath(virtualMocks, from, moduleName);
+      : this._getVirtualMockPath(virtualMocks, from, moduleName, options);
   }
 
   private _getMockPath(
@@ -373,12 +387,13 @@ export default class Resolver {
     virtualMocks: Map<string, boolean>,
     from: Config.Path,
     moduleName: string,
+    options?: ResolveModuleConfig,
   ): Config.Path {
     const virtualMockPath = this.getModulePath(from, moduleName);
     return virtualMocks.get(virtualMockPath)
       ? virtualMockPath
       : moduleName
-      ? this.resolveModule(from, moduleName)
+      ? this.resolveModule(from, moduleName, options)
       : from;
   }