fix: support import cjs from mjs (#9850)

Author: SimenB

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 ### Fixes
 
+- `[jest-runtime]` Support importing CJS from ESM using `import` statements ([#9850](https://github.com/facebook/jest/pull/9850))
+
 ### Chore & Maintenance
 
 ### Performance
@@ -19,8 +21,8 @@
 ### Fixes
 
 - `[expect]` Restore support for passing functions to `toHaveLength` matcher ([#9796](https://github.com/facebook/jest/pull/9796))
-- `[jest-circus]` Throw on nested test definitions ([#9828](https://github.com/facebook/jest/pull/9828))
 - `[jest-changed-files]` `--only-changed` should include staged files ([#9799](https://github.com/facebook/jest/pull/9799))
+- `[jest-circus]` Throw on nested test definitions ([#9828](https://github.com/facebook/jest/pull/9828))
 - `[jest-each]` `each` will throw an error when called with too many arguments ([#9818](https://github.com/facebook/jest/pull/9818))
 - `[jest-runner]` Don't print warning to stdout when using `--json` ([#9843](https://github.com/facebook/jest/pull/9843))
 

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

@@ -2,7 +2,7 @@
 
 exports[`on node >=12.16.0 runs test with native ESM 1`] = `
 Test Suites: 1 passed, 1 total
-Tests:       8 passed, 8 total
+Tests:       9 passed, 9 total
 Snapshots:   0 total
 Time:        <<REPLACED>>
 Ran all test suites.

e2e/native-esm/__tests__/native-esm.test.js

@@ -10,6 +10,7 @@ import {createRequire} from 'module';
 import {dirname, resolve} from 'path';
 import {fileURLToPath} from 'url';
 import staticImportedStateful from '../stateful.mjs';
+import staticImportedStatefulFromCjs from '../fromCjs.mjs';
 import {double} from '../index';
 
 test('should have correct import.meta', () => {
@@ -78,6 +79,10 @@ test('import from mjs and import(mjs) should share caches', async () => {
   expect(staticImportedStateful()).toBe(6);
 });
 
+test('import cjs via import statement', () => {
+  expect(staticImportedStatefulFromCjs(4)).toBe(2);
+});
+
 test('handle unlinked dynamic imports', async () => {
   const {double: deepDouble} = await import('../dynamicImport');
 

e2e/native-esm/fromCjs.mjs

@@ -0,0 +1,8 @@
+/**
+ * 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.
+ */
+
+export {default} from './commonjs.cjs';

packages/jest-resolve/src/shouldLoadAsEsm.ts

@@ -7,11 +7,11 @@
 
 import {dirname, extname} from 'path';
 // @ts-ignore: experimental, not added to the types
-import {SourceTextModule} from 'vm';
+import {SyntheticModule} from 'vm';
 import type {Config} from '@jest/types';
 import readPkgUp = require('read-pkg-up');
 
-const runtimeSupportsVmModules = typeof SourceTextModule === 'function';
+const runtimeSupportsVmModules = typeof SyntheticModule === 'function';
 
 const cachedFileLookups = new Map<string, boolean>();
 const cachedDirLookups = new Map<string, boolean>();

packages/jest-runtime/src/index.ts

@@ -112,7 +112,7 @@ const EVAL_RESULT_VARIABLE = 'Object.<anonymous>';
 
 type RunScriptEvalResult = {[EVAL_RESULT_VARIABLE]: ModuleWrapper};
 
-const runtimeSupportsVmModules = typeof SourceTextModule === 'function';
+const runtimeSupportsVmModules = typeof SyntheticModule === 'function';
 
 /* eslint-disable-next-line no-redeclare */
 class Runtime {
@@ -351,39 +351,15 @@ class Runtime {
       const module = new SourceTextModule(transformedFile.code, {
         context,
         identifier: modulePath,
-        importModuleDynamically: (
-          specifier: string,
-          referencingModule: VMModule,
-        ) => {
-          const resolved = this._resolveModule(
-            referencingModule.identifier,
-            specifier,
-          );
-          if (
-            this._resolver.isCoreModule(resolved) ||
-            this.unstable_shouldLoadAsEsm(resolved)
-          ) {
-            return this.loadEsmModule(resolved);
-          }
-
-          return this.loadCjsAsEsm(
-            referencingModule.identifier,
-            resolved,
-            context,
-          );
-        },
+        importModuleDynamically: this.linkModules.bind(this),
         initializeImportMeta(meta: ImportMeta) {
           meta.url = pathToFileURL(modulePath).href;
         },
       });
 
       this._esmoduleRegistry.set(cacheKey, module);
 
-      await module.link((specifier: string, referencingModule: VMModule) =>
-        this.loadEsmModule(
-          this._resolveModule(referencingModule.identifier, specifier),
-        ),
-      );
+      await module.link(this.linkModules.bind(this));
 
       await module.evaluate();
     }
@@ -395,6 +371,25 @@ class Runtime {
     return module;
   }
 
+  private async linkModules(specifier: string, referencingModule: VMModule) {
+    const resolved = this._resolveModule(
+      referencingModule.identifier,
+      specifier,
+    );
+    if (
+      this._resolver.isCoreModule(resolved) ||
+      this.unstable_shouldLoadAsEsm(resolved)
+    ) {
+      return this.loadEsmModule(resolved);
+    }
+
+    return this.loadCjsAsEsm(
+      referencingModule.identifier,
+      resolved,
+      referencingModule.context,
+    );
+  }
+
   async unstable_importModule(
     from: Config.Path,
     moduleName?: string,