fix: add support for ESM test environments with TypeScript (.ts, .mts)

Author: ahnpnl

CHANGELOG.md

@@ -10,6 +10,7 @@
 - `[jest-reporters]` Fix issue where console output not displayed for GHA reporter even with `silent: false` option ([#15864](https://github.com/jestjs/jest/pull/15864))
 - `[jest-runtime]` Fix issue where user cannot utilize dynamic import despite specifying `--experimental-vm-modules` Node option ([#15842](https://github.com/jestjs/jest/pull/15842))
 - `[jest-test-sequencer]` Fix issue where failed tests due to compilation errors not getting re-executed even with `--onlyFailures` CLI option ([#15851](https://github.com/jestjs/jest/pull/15851))
+- `[jest-runner, jest-transformer]` support custom test environment written in ESM with `TypeScript` extensions ([#15885](https://github.com/jestjs/jest/pull/15885)), fixes downstream [issue](https://github.com/kulshekhar/ts-jest/issues/4195)
 
 ### Chore & Maintenance
 

e2e/__tests__/testEnvironmentEsm.ts

@@ -6,11 +6,46 @@
  */
 
 import {resolve} from 'path';
-import runJest from '../runJest';
+import {json as runJestJson} from '../runJest';
 
-it('support test environment written in ESM', () => {
-  const DIR = resolve(__dirname, '../test-environment-esm');
-  const {exitCode} = runJest(DIR);
+const DIR = resolve(__dirname, '../test-environment-esm');
+
+it('support test environment written in ESM with `.ts` extension', () => {
+  const {exitCode, json} = runJestJson(DIR, ['testUsingTsEnv.test.js'], {
+    nodeOptions: '--experimental-vm-modules --no-warnings',
+  });
+
+  expect(exitCode).toBe(0);
+  expect(json.numTotalTests).toBe(1);
+  expect(json.numPassedTests).toBe(1);
+});
+
+it('support test environment written in ESM with `.mts` extension', () => {
+  const {exitCode, json} = runJestJson(DIR, ['testUsingMtsEnv.test.js'], {
+    nodeOptions: '--experimental-vm-modules --no-warnings',
+  });
+
+  expect(exitCode).toBe(0);
+  expect(json.numTotalTests).toBe(1);
+  expect(json.numPassedTests).toBe(1);
+});
+
+it('support test environment written in ESM with `.js` extension', () => {
+  const {exitCode, json} = runJestJson(DIR, ['testUsingJsEnv.test.js'], {
+    nodeOptions: '--experimental-vm-modules --no-warnings',
+  });
+
+  expect(exitCode).toBe(0);
+  expect(json.numTotalTests).toBe(1);
+  expect(json.numPassedTests).toBe(1);
+});
+
+it('support test environment written in ESM with `.mjs` extension', () => {
+  const {exitCode, json} = runJestJson(DIR, ['testUsingMjsEnv.test.js'], {
+    nodeOptions: '--experimental-vm-modules --no-warnings',
+  });
 
   expect(exitCode).toBe(0);
+  expect(json.numTotalTests).toBe(1);
+  expect(json.numPassedTests).toBe(1);
 });

e2e/test-environment-esm/__tests__/testUsingESMTestEnv.test.js renamed to e2e/test-environment-esm/__tests__/testUsingJsEnv.test.js

@@ -3,9 +3,11 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-environment <rootDir>/env-3.js
  */
 'use strict';
 
-test('dummy', () => {
+test('should pass', () => {
   expect(globalThis.someVar).toBe(42);
 });

e2e/test-environment-esm/__tests__/testUsingMjsEnv.test.js

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-environment <rootDir>/env-4.mjs
+ */
+'use strict';
+
+test('should pass', () => {
+  expect(globalThis.someVar).toBe(42);
+});

e2e/test-environment-esm/__tests__/testUsingMtsEnv.test.js

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-environment <rootDir>/env-1.mts
+ */
+'use strict';
+
+test('should pass', () => {
+  expect(globalThis.someVar).toBe(42);
+});

e2e/test-environment-esm/__tests__/testUsingTsEnv.test.js

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-environment <rootDir>/env-2.ts
+ */
+'use strict';
+
+test('should pass', () => {
+  expect(globalThis.someVar).toBe(42);
+});

e2e/test-environment-esm/babel.config.cjs

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+module.exports = {
+  presets: [
+    ['@babel/preset-env', {targets: {node: 'current'}}],
+    '@babel/preset-typescript',
+  ],
+};

e2e/test-environment-esm/env-1.mts

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import type {
+  EnvironmentContext,
+  JestEnvironmentConfig,
+} from '@jest/environment';
+import {TestEnvironment} from 'jest-environment-node';
+
+declare global {
+  interface ImportMeta {
+    someVar: number;
+  }
+}
+
+export default class Env extends TestEnvironment {
+  constructor(config: JestEnvironmentConfig, context: EnvironmentContext) {
+    super(config, context);
+    import.meta.someVar = 42;
+    this.global.someVar = import.meta.someVar;
+  }
+}

e2e/test-environment-esm/env-2.ts

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import type {
+  EnvironmentContext,
+  JestEnvironmentConfig,
+} from '@jest/environment';
+import {TestEnvironment} from 'jest-environment-node';
+
+declare global {
+  interface ImportMeta {
+    someVar: number;
+  }
+}
+
+export default class Env extends TestEnvironment {
+  constructor(config: JestEnvironmentConfig, context: EnvironmentContext) {
+    super(config, context);
+    import.meta.someVar = 42;
+    this.global.someVar = import.meta.someVar;
+  }
+}

e2e/test-environment-esm/EnvESM.js renamed to e2e/test-environment-esm/env-3.js

@@ -8,8 +8,9 @@
 import {TestEnvironment} from 'jest-environment-node';
 
 export default class Env extends TestEnvironment {
-  constructor(...args) {
-    super(...args);
-    this.global.someVar = 42;
+  constructor(config, context) {
+    super(config, context);
+    import.meta.someVar = 42;
+    this.global.someVar = import.meta.someVar;
   }
 }