fix: add require.main when using isolateModules (#10621)

Author: flozender

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 - `[jest-runner, jest-runtime]` fix: `require.main` undefined with `createRequire()` ([#10610](https://github.com/facebook/jest/pull/10610))
 - `[jest-runtime]` add missing `module.path` property ([#10615](https://github.com/facebook/jest/pull/10615))
+- `[jest-runtime]` fix: add `mainModule` instance variable to runtime ([#10621](https://github.com/facebook/jest/pull/10621))
 - `[jest-validate]` Show suggestion only when unrecognized cli param is longer than 1 character ([#10604](https://github.com/facebook/jest/pull/10604))
 - `[jest-validate]` Validate `testURL` as CLI option ([#10595](https://github.com/facebook/jest/pull/10595))
 

e2e/__tests__/requireMainIsolateModules.test.ts

@@ -0,0 +1,14 @@
+/**
+ * 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 runJest from '../runJest';
+
+test('`require.main` on using `jest.isolateModules` should not be undefined', () => {
+ const {exitCode} = runJest('require-main-isolate-modules');
+
+ expect(exitCode).toBe(0);
+});

e2e/require-main-isolate-modules/__tests__/index.test.js

@@ -0,0 +1,13 @@
+/**
+ * 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.
+ */
+let foo;
+
+jest.isolateModules(() => (foo = require('../index')));
+
+test('`require.main` on using `jest.isolateModules` should not be undefined', () => {
+ expect(foo()).toEqual(1);
+});

e2e/require-main-isolate-modules/child.js

@@ -0,0 +1,7 @@
+/**
+ * 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 = 1;

e2e/require-main-isolate-modules/index.js

@@ -0,0 +1,7 @@
+/**
+ * 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 = () => require.main.require('../child');

e2e/require-main-isolate-modules/package.json

@@ -0,0 +1,5 @@
+{
+ "jest": {
+ "testEnvironment": "node"
+ }
+}

packages/jest-runtime/src/__tests__/runtime_require_module.test.js

@@ -45,6 +45,7 @@ describe('Runtime requireModule', () => {
  'path',
  'parent',
  'paths',
+ 'main',
  ]);
  }));
 
@@ -63,6 +64,7 @@ describe('Runtime requireModule', () => {
  'path',
  'parent',
  'paths',
+ 'main',
  ]);
  }));
 

packages/jest-runtime/src/index.ts

@@ -150,6 +150,7 @@ class Runtime {
  | null;
  private _internalModuleRegistry: ModuleRegistry;
  private _isCurrentlyExecutingManualMock: string | null;
+ private _mainModule: Module | null;
  private _mockFactories: Map<string, () => unknown>;
  private _mockMetaDataCache: Map<
  string,
@@ -202,6 +203,7 @@ class Runtime {
  this._explicitShouldMock = new Map();
  this._internalModuleRegistry = new Map();
  this._isCurrentlyExecutingManualMock = null;
+ this._mainModule = null;
  this._mockFactories = new Map();
  this._mockRegistry = new Map();
  // during setup, this cannot be null (and it's fine to explode if it is)
@@ -891,6 +893,7 @@ class Runtime {
  this.resetModules();
 
  this._internalModuleRegistry.clear();
+ this._mainModule = null;
  this._mockFactories.clear();
  this._mockMetaDataCache.clear();
  this._shouldMockModuleCache.clear();
@@ -1064,6 +1067,15 @@ class Runtime {
  }),
  ];
 
+ if (!this._mainModule && filename === this._testPath) {
+ this._mainModule = module;
+ }
+
+ Object.defineProperty(module, 'main', {
+ enumerable: true,
+ value: this._mainModule,
+ });
+
  try {
  compiledFunction.call(
  module.exports,