jest-utils: add a getter for process.domain

CHANGELOG.md

@@ -49,6 +49,7 @@
 - `[jest-snapshot]` [**BREAKING**] Distinguish empty string from internal snapshot not written ([#8898](https://github.com/facebook/jest/pull/8898))
 - `[jest-snapshot]` [**BREAKING**] Remove `report` method and throw matcher errors ([#9049](https://github.com/facebook/jest/pull/9049))
 - `[jest-transform]` Properly cache transformed files across tests ([#8890](https://github.com/facebook/jest/pull/8890))
+- `[jest-utils]`Allow querying process.domain ([#9136](https://github.com/facebook/jest/pull/9136))
 - `[jest-transform]` Don't fail the test suite when a generated source map is invalid ([#9058](https://github.com/facebook/jest/pull/9058))
 
 ### Chore & Maintenance

globalSetupFile.js

@@ -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.
+ */
+
+// Jest creates a copy of the global 'process' object and uses it instead of the one provided by node.
+// Since 'require'-ing the 'domain' module has a side-effect that modifies "process" to make it work with domains,
+// 'domain' has to be required before Jest performs the copy, i.e. in the global-setup phase represented by this file.
+
+module.exports = () => {
+  require('domain');
+};

jest.config.js

@@ -5,8 +5,6 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-'use strict';
-
 module.exports = {
   collectCoverageFrom: [
     '**/packages/*/**/*.js',
@@ -20,6 +18,7 @@ module.exports = {
     '!**/vendor/**',
     '!e2e/**',
   ],
+  globalSetup: '<rootDir>/globalSetupFile.js',
   modulePathIgnorePatterns: [
     'examples/.*',
     'packages/.*/build',

packages/jest-util/src/__tests__/createProcessObject.test.ts

@@ -6,6 +6,7 @@
  */
 
 import {EventEmitter} from 'events';
+import * as domain from 'domain';
 
 let createProcessObject;
 
@@ -105,3 +106,10 @@ it('checks that process.env works as expected in Windows platforms', () => {
   expect(fake.hasOwnProperty('PROP_STRING')).toBe(false);
   expect(fake.hasOwnProperty('PROP_string')).toBe(false);
 });
+
+test('allows retrieving the current domain', () => {
+  const aDomain = domain.create();
+  Object.defineProperty(process, 'domain', {get: () => aDomain});
+
+  expect(createProcessObject().domain).toEqual(aDomain);
+});

packages/jest-util/src/createProcessObject.ts

@@ -112,5 +112,11 @@ export default function() {
   newProcess.env = createProcessEnv();
   newProcess.send = () => {};
 
+  Object.defineProperty(newProcess, 'domain', {
+    get() {
+      return process.domain;
+    },
+  });
+
   return newProcess;
 }