fix(jest-runtime): handle function module.exports for CJS-from-ESM named exports (#16150)

CHANGELOG.md

@@ -1,5 +1,11 @@
 ## main
 
+## 30.4.2
+
+### Fixes
+
+- `[jest-runtime]` Fix named imports from CJS modules whose `module.exports` is a function with own-property exports ([#16150](https://github.com/jestjs/jest/pull/16150))
+
 ## 30.4.1
 
 ### Features

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

@@ -2,7 +2,7 @@
 
 exports[`runs ESM/CJS interop fixture (__esModule unwrapping, named exports, singleton caching) 1`] = `
 "Test Suites: 1 passed, 1 total
-Tests:       6 passed, 6 total
+Tests:       8 passed, 8 total
 Snapshots:   0 total
 Time:        <<REPLACED>>
 Ran all test suites matching cjs-esm-interop."

e2e/native-esm-cjs-require/__tests__/cjs-esm-interop.test.js

@@ -7,6 +7,10 @@
 
 import greet, {helper} from '../babel-style-default.cjs';
 import plainDefault, {multiply, value} from '../plain-cjs.cjs';
+import fnDefault, {
+  helper as fnHelper,
+  splitCookiesString,
+} from '../fn-exports.cjs';
 import {getCount as countA, increment as incA} from '../importer-a.mjs';
 import {getCount as countB, increment as incB} from '../importer-b.mjs';
 
@@ -38,6 +42,18 @@ test('named imports from plain CJS work', () => {
   expect(multiply(6, 7)).toBe(42);
 });
 
+// ── CJS with function module.exports ─────────────────────────────────────────
+
+test('default import of function-export CJS is the function itself', () => {
+  expect(typeof fnDefault).toBe('function');
+  expect(fnDefault('x')).toEqual({input: 'x'});
+});
+
+test('named imports from function-export CJS work', () => {
+  expect(splitCookiesString('a,b')).toEqual(['a', 'b']);
+  expect(fnHelper(21)).toBe(42);
+});
+
 // ── CJS-as-ESM caching (singleton) ───────────────────────────────────────────
 
 test('two ESM importers of the same CJS module share one singleton instance', () => {

e2e/native-esm-cjs-require/fn-exports.cjs

@@ -0,0 +1,23 @@
+/**
+ * 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.
+ */
+
+// CJS pattern where module.exports is a function with own-property named exports.
+'use strict';
+
+function parse(input) {
+  return {input};
+}
+
+parse.splitCookiesString = function splitCookiesString(str) {
+  return str.split(',');
+};
+
+parse.helper = function helper(x) {
+  return x * 2;
+};
+
+module.exports = parse;

e2e/native-esm/yarn.lock

@@ -673,13 +673,10 @@ __metadata:
   languageName: node
   linkType: hard
 
-"ip-address@npm:^9.0.5":
-  version: 9.0.5
-  resolution: "ip-address@npm:9.0.5"
-  dependencies:
-    jsbn: "npm:1.1.0"
-    sprintf-js: "npm:^1.1.3"
-  checksum: 10/1ed81e06721af012306329b31f532b5e24e00cb537be18ddc905a84f19fe8f83a09a1699862bf3a1ec4b9dea93c55a3fa5faf8b5ea380431469df540f38b092c
+"ip-address@npm:^10.1.1":
+  version: 10.2.0
+  resolution: "ip-address@npm:10.2.0"
+  checksum: 10/12fec399e1af5753ac322e47a6d81a50d3a528b3abb17c09525b2a2edcaedcca628c40520706f7037bc4d8e951b0296c47e7b86d0a8e6e2335c8f0ba4afcfac1
   languageName: node
   linkType: hard
 
@@ -734,13 +731,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"jsbn@npm:1.1.0":
-  version: 1.1.0
-  resolution: "jsbn@npm:1.1.0"
-  checksum: 10/bebe7ae829bbd586ce8cbe83501dd8cb8c282c8902a8aeeed0a073a89dc37e8103b1244f3c6acd60278bcbfe12d93a3f83c9ac396868a3b3bbc3c5e5e3b648ef
-  languageName: node
-  linkType: hard
-
 "lodash.snakecase@npm:^4.1.1":
   version: 4.1.1
   resolution: "lodash.snakecase@npm:4.1.1"
@@ -1217,19 +1207,12 @@ __metadata:
   linkType: hard
 
 "socks@npm:^2.8.3":
-  version: 2.8.4
-  resolution: "socks@npm:2.8.4"
+  version: 2.8.9
+  resolution: "socks@npm:2.8.9"
   dependencies:
-    ip-address: "npm:^9.0.5"
+    ip-address: "npm:^10.1.1"
     smart-buffer: "npm:^4.2.0"
-  checksum: 10/ab3af97aeb162f32c80e176c717ccf16a11a6ebb4656a62b94c0f96495ea2a1f4a8206c04b54438558485d83d0c5f61920c07a1a5d3963892a589b40cc6107dd
-  languageName: node
-  linkType: hard
-
-"sprintf-js@npm:^1.1.3":
-  version: 1.1.3
-  resolution: "sprintf-js@npm:1.1.3"
-  checksum: 10/e7587128c423f7e43cc625fe2f87e6affdf5ca51c1cc468e910d8aaca46bb44a7fbcfa552f787b1d3987f7043aeb4527d1b99559e6621e01b42b3f45e5a24cbb
+  checksum: 10/8675e6b023faeaa5c2511664b106fd21f5d5ecb403584412e0efae58a76e0c0661c0c18ca340988f6cb398232308dae85fb710f847c9c6e0a6af33b07e4cd33a
   languageName: node
   linkType: hard
 

packages/jest-runtime/src/internals/__tests__/syntheticBuilders.test.ts

@@ -130,6 +130,27 @@ describe('syntheticBuilders', () => {
       },
     );
 
+    testWithVmEsm(
+      'exposes own-property named exports when module.exports is a function',
+      async () => {
+        // Pattern: `module.exports = function parse() {}; parse.helper = ...`
+        function parse() {}
+        (parse as any).helper = () => 'h';
+        (parse as any).splitCookiesString = () => ['a', 'b'];
+        const m = buildCjsAsEsmSyntheticModule(
+          '/from.js',
+          '/mod.cjs',
+          context(),
+          () => parse,
+          makeCache(['helper', 'splitCookiesString']),
+        );
+        const ns = await evaluate(m);
+        expect(ns.default).toBe(parse);
+        expect(ns.helper).toBe((parse as any).helper);
+        expect(ns.splitCookiesString).toBe((parse as any).splitCookiesString);
+      },
+    );
+
     testWithVmEsm('handles non-object module.exports', async () => {
       const m = buildCjsAsEsmSyntheticModule(
         '/from.js',

packages/jest-runtime/src/internals/syntheticBuilders.ts

@@ -114,9 +114,10 @@ export function buildCjsAsEsmSyntheticModule(
   const parsedExports = cjsExportsCache.getExportsOf(from, modulePath);
 
   // CJS modules can legally set `module.exports` to `null` or a primitive.
+  // Functions are also valid (e.g. `module.exports = fn; fn.helper = ...`).
   const cjsRecord =
-    typeof cjs === 'object' && cjs !== null
-      ? (cjs as Record<string, unknown>)
+    cjs !== null && (typeof cjs === 'object' || typeof cjs === 'function')
+      ? cjs
       : null;
 
   const allCandidates = new Set([
@@ -126,19 +127,19 @@ export function buildCjsAsEsmSyntheticModule(
 
   const cjsExports = [...allCandidates].filter(exportName => {
     // `default` is handled separately below as the whole module.exports.
-    if (exportName === 'default') {
+    if (exportName === 'default' || cjsRecord == null) {
       return false;
     }
-    return cjsRecord
-      ? Object.hasOwnProperty.call(cjsRecord, exportName)
-      : false;
+    return Object.hasOwn(cjsRecord, exportName);
   });
 
   return new SyntheticModule(
     [...cjsExports, 'default'],
     function () {
-      for (const exportName of cjsExports) {
-        this.setExport(exportName, (cjs as any)[exportName]);
+      if (cjsRecord != null) {
+        for (const exportName of cjsExports) {
+          this.setExport(exportName, Reflect.get(cjsRecord, exportName));
+        }
       }
       // module.exports is the ESM default, matching Node's CJS-from-ESM behavior.
       // __esModule is not honored — see Node docs on named exports from CJS.

packages/jest-runtime/tsconfig.json

@@ -2,7 +2,7 @@
   "extends": "../../tsconfig.json",
   "compilerOptions": {
     // needed for WebAssembly, see https://github.com/microsoft/TypeScript-DOM-lib-generator/issues/826
-    "lib": ["dom"],
+    "lib": ["es2023", "dom"],
     "rootDir": "src",
     "outDir": "build"
   },

yarn.lock

@@ -13622,13 +13622,10 @@ __metadata:
   languageName: node
   linkType: hard
 
-"ip-address@npm:^9.0.5":
-  version: 9.0.5
-  resolution: "ip-address@npm:9.0.5"
-  dependencies:
-    jsbn: "npm:1.1.0"
-    sprintf-js: "npm:^1.1.3"
-  checksum: 10/1ed81e06721af012306329b31f532b5e24e00cb537be18ddc905a84f19fe8f83a09a1699862bf3a1ec4b9dea93c55a3fa5faf8b5ea380431469df540f38b092c
+"ip-address@npm:^10.1.1":
+  version: 10.2.0
+  resolution: "ip-address@npm:10.2.0"
+  checksum: 10/12fec399e1af5753ac322e47a6d81a50d3a528b3abb17c09525b2a2edcaedcca628c40520706f7037bc4d8e951b0296c47e7b86d0a8e6e2335c8f0ba4afcfac1
   languageName: node
   linkType: hard
 
@@ -15100,13 +15097,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"jsbn@npm:1.1.0":
-  version: 1.1.0
-  resolution: "jsbn@npm:1.1.0"
-  checksum: 10/bebe7ae829bbd586ce8cbe83501dd8cb8c282c8902a8aeeed0a073a89dc37e8103b1244f3c6acd60278bcbfe12d93a3f83c9ac396868a3b3bbc3c5e5e3b648ef
-  languageName: node
-  linkType: hard
-
 "jsc-safe-url@npm:^0.2.2":
   version: 0.2.4
   resolution: "jsc-safe-url@npm:0.2.4"
@@ -21119,12 +21109,12 @@ __metadata:
   linkType: hard
 
 "socks@npm:^2.8.3":
-  version: 2.8.4
-  resolution: "socks@npm:2.8.4"
+  version: 2.8.9
+  resolution: "socks@npm:2.8.9"
   dependencies:
-    ip-address: "npm:^9.0.5"
+    ip-address: "npm:^10.1.1"
     smart-buffer: "npm:^4.2.0"
-  checksum: 10/ab3af97aeb162f32c80e176c717ccf16a11a6ebb4656a62b94c0f96495ea2a1f4a8206c04b54438558485d83d0c5f61920c07a1a5d3963892a589b40cc6107dd
+  checksum: 10/8675e6b023faeaa5c2511664b106fd21f5d5ecb403584412e0efae58a76e0c0661c0c18ca340988f6cb398232308dae85fb710f847c9c6e0a6af33b07e4cd33a
   languageName: node
   linkType: hard
 
@@ -21279,13 +21269,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"sprintf-js@npm:^1.1.3":
-  version: 1.1.3
-  resolution: "sprintf-js@npm:1.1.3"
-  checksum: 10/e7587128c423f7e43cc625fe2f87e6affdf5ca51c1cc468e910d8aaca46bb44a7fbcfa552f787b1d3987f7043aeb4527d1b99559e6621e01b42b3f45e5a24cbb
-  languageName: node
-  linkType: hard
-
 "sprintf-js@npm:~1.0.2":
   version: 1.0.3
   resolution: "sprintf-js@npm:1.0.3"