fix(jest-config): add mjs and cjs to default moduleFileExtensions config

CHANGELOG.md

@@ -50,6 +50,7 @@
 - `[jest-circus, @jest/types]` Disallow undefined value in `TestContext` type ([#12507](https://github.com/facebook/jest/pull/12507))
 - `[jest-config]` Correctly detect CI environment and update snapshots accordingly ([#12378](https://github.com/facebook/jest/pull/12378))
 - `[jest-config]` Pass `moduleTypes` to `ts-node` to enforce CJS when transpiling ([#12397](https://github.com/facebook/jest/pull/12397))
+- `[jest-config]` [**BREAKING**] Add `mjs` and `cjs` to default `moduleFileExtensions` config ([12578](https://github.com/facebook/jest/pull/12578))
 - `[jest-config, jest-haste-map]` Allow searching for tests in `node_modules` by exposing `retainAllFiles` ([#11084](https://github.com/facebook/jest/pull/11084))
 - `[jest-core]` [**BREAKING**] Exit with status `1` if no tests are found with `--findRelatedTests` flag ([#12487](https://github.com/facebook/jest/pull/12487))
 - `[jest-each]` `%#` is not replaced with index of the test case ([#12517](https://github.com/facebook/jest/pull/12517))

docs/Configuration.md

@@ -571,7 +571,7 @@ An array of directory names to be searched recursively up from the requiring mod
 
 ### `moduleFileExtensions` \[array<string>]
 
-Default: `["js", "jsx", "ts", "tsx", "json", "node"]`
+Default: `["js", "mjs", "cjs", "jsx", "ts", "tsx", "json", "node"]`
 
 An array of file extensions your modules use. If you require modules without specifying a file extension, these are the extensions Jest will look for, in left-to-right order.
 

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

@@ -30,6 +30,8 @@ exports[`--showConfig outputs config info and exits 1`] = `
       ],
       "moduleFileExtensions": [
         "js",
+        "mjs",
+        "cjs",
         "jsx",
         "ts",
         "tsx",

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

@@ -0,0 +1,9 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`testMatch should able to match file with cjs and mjs extension 1`] = `
+"Test Suites: 2 passed, 2 total
+Tests:       2 passed, 2 total
+Snapshots:   0 total
+Time:        <<REPLACED>>
+Ran all test suites."
+`;

e2e/__tests__/testMatch.test.ts

@@ -0,0 +1,16 @@
+/**
+ * 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 {extractSummary} from '../Utils';
+import runJest from '../runJest';
+
+it('testMatch should able to match file with cjs and mjs extension', () => {
+  const result = runJest('test-match');
+  expect(result.exitCode).toBe(0);
+  const {summary} = extractSummary(result.stderr);
+  expect(summary).toMatchSnapshot();
+});

e2e/test-match/package.json

@@ -0,0 +1,7 @@
+{
+  "jest": {
+    "testMatch": [
+      "**/test-suites/*.?js"
+    ]
+  }
+}

e2e/test-match/test-suites/sample-suite.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.
+ */
+
+test('mjs extension', () => {
+  expect(1).toBe(1);
+});

e2e/test-match/test-suites/sample-suite2.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.
+ */
+
+test('cjs extension', () => {
+  expect(1).toBe(1);
+});

packages/jest-cli/src/init/__tests__/__snapshots__/init.test.js.snap

@@ -191,6 +191,8 @@ module.exports = {
   // An array of file extensions your modules use
   // moduleFileExtensions: [
   //   "js",
+  //   "mjs",
+  //   "cjs",
   //   "jsx",
   //   "ts",
   //   "tsx",

packages/jest-config/src/Defaults.ts

@@ -44,7 +44,16 @@ const defaultOptions: Config.DefaultOptions = {
   maxConcurrency: 5,
   maxWorkers: '50%',
   moduleDirectories: ['node_modules'],
-  moduleFileExtensions: ['js', 'jsx', 'ts', 'tsx', 'json', 'node'],
+  moduleFileExtensions: [
+    'js',
+    'mjs',
+    'cjs',
+    'jsx',
+    'ts',
+    'tsx',
+    'json',
+    'node',
+  ],
   moduleNameMapper: {},
   modulePathIgnorePatterns: [],
   noStackTrace: false,

packages/jest-config/src/ValidConfig.ts

@@ -74,7 +74,16 @@ const initialOptions: Config.InitialOptions = {
   maxConcurrency: 5,
   maxWorkers: '50%',
   moduleDirectories: ['node_modules'],
-  moduleFileExtensions: ['js', 'json', 'jsx', 'ts', 'tsx', 'node'],
+  moduleFileExtensions: [
+    'js',
+    'mjs',
+    'cjs',
+    'json',
+    'jsx',
+    'ts',
+    'tsx',
+    'node',
+  ],
   moduleNameMapper: {
     '^React$': '<rootDir>/node_modules/react',
   },

packages/jest-config/src/__tests__/normalize.test.ts

@@ -1668,6 +1668,8 @@ describe('moduleFileExtensions', () => {
 
     expect(options.moduleFileExtensions).toEqual([
       'js',
+      'mjs',
+      'cjs',
       'jsx',
       'ts',
       'tsx',

packages/jest-transform/src/ScriptTransformer.ts

@@ -759,7 +759,10 @@ class ScriptTransformer {
         }
       },
       {
-        exts: this._config.moduleFileExtensions.map(ext => `.${ext}`),
+        // Exclude `mjs` extension when addHook because pirates don't support hijack es module
+        exts: this._config.moduleFileExtensions
+          .filter(ext => ext !== 'mjs')
+          .map(ext => `.${ext}`),
         ignoreNodeModules: false,
         matcher: filename => {
           if (transforming) {