feat(jest-environment-jsdom): allow specifying `customExportCondition…

…s` instead of the default `'browser'`

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Features
 
+- `[jest-environment-jsdom]` Allow specifying `customExportConditions` instead of the default `'browser'` ([#12774](https://github.com/facebook/jest/pull/12774))
+
 ### Fixes
 
 ### Chore & Maintenance

e2e/resolve-conditions/.gitignore

@@ -0,0 +1 @@
+!node_modules

e2e/resolve-conditions/__tests__/jsdom-custom-export-conditions.test.mjs

@@ -0,0 +1,15 @@
+/**
+ * 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-environment jest-environment-jsdom
+ * @jest-environment-options {"customExportConditions": ["special"]}
+ */
+
+import {fn} from 'fake-dual-dep';
+
+test('returns correct message', () => {
+  expect(fn()).toEqual('hello from special');
+});

packages/jest-environment-jsdom/src/index.ts

@@ -33,6 +33,7 @@ export default class JSDOMEnvironment implements JestEnvironment<number> {
   global: Win;
   private errorEventListener: ((event: Event & {error: Error}) => void) | null;
   moduleMocker: ModuleMocker | null;
+  customExportConditions: Array<string>;
 
   constructor(config: JestEnvironmentConfig, context: EnvironmentContext) {
     const {projectConfig} = config;
@@ -109,6 +110,20 @@ export default class JSDOMEnvironment implements JestEnvironment<number> {
       return originalRemoveListener.apply(this, args);
     };
 
+    if ('customExportConditions' in projectConfig.testEnvironmentOptions) {
+      const {customExportConditions} = projectConfig.testEnvironmentOptions;
+      if (
+        Array.isArray(customExportConditions) &&
+        customExportConditions.every(item => typeof item === 'string')
+      ) {
+        this.customExportConditions = customExportConditions;
+      } else {
+        throw new Error(
+          'Custom export conditions specified but they are not an array of strings',
+        );
+      }
+    }
+
     this.moduleMocker = new ModuleMocker(global as any);
 
     this.fakeTimers = new LegacyFakeTimers({
@@ -158,7 +173,7 @@ export default class JSDOMEnvironment implements JestEnvironment<number> {
   }
 
   exportConditions(): Array<string> {
-    return ['browser'];
+    return this.customExportConditions ?? ['browser'];
   }
 
   getVmContext(): Context | null {