fix(esm): evaluate node core modules on dynamic import (#10622)

Author: SimenB

CHANGELOG.md

@@ -6,9 +6,10 @@
 
 ### Fixes
 
-- `[jest-runner, jest-runtime]` fix: `require.main` undefined with `createRequire()` ([#10610](https://github.com/facebook/jest/pull/10610))
+- `[jest-runner, jest-runtime]` `require.main` should not be `undefined` with `createRequire()` ([#10610](https://github.com/facebook/jest/pull/10610))
 - `[jest-runtime]` add missing `module.path` property ([#10615](https://github.com/facebook/jest/pull/10615))
-- `[jest-runtime]` fix: add `mainModule` instance variable to runtime ([#10621](https://github.com/facebook/jest/pull/10621))
+- `[jest-runtime]` Add `mainModule` instance variable to runtime ([#10621](https://github.com/facebook/jest/pull/10621))
+- `[jest-runtime]` Evaluate Node core modules on dynamic `import()` ([#10622](https://github.com/facebook/jest/pull/10622))
 - `[jest-validate]` Show suggestion only when unrecognized cli param is longer than 1 character ([#10604](https://github.com/facebook/jest/pull/10604))
 - `[jest-validate]` Validate `testURL` as CLI option ([#10595](https://github.com/facebook/jest/pull/10595))
 

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

@@ -2,7 +2,7 @@
 
 exports[`on node ^12.16.0 || >=13.7.0 runs test with native ESM 1`] = `
 Test Suites: 1 passed, 1 total
-Tests:       13 passed, 13 total
+Tests:       14 passed, 14 total
 Snapshots:   0 total
 Time:        <<REPLACED>>
 Ran all test suites.

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

@@ -49,6 +49,13 @@ test('should support importing node core modules', () => {
   });
 });
 
+test('should support importing node core modules dynamically', async () => {
+  // it's important that this module has _not_ been imported at the top level
+  const assert = await import('assert');
+
+  expect(typeof assert.strictEqual).toBe('function');
+});
+
 test('dynamic import should work', async () => {
   const {double: importedDouble} = await import('../index');
 

packages/jest-runtime/src/index.ts

@@ -466,7 +466,7 @@ class Runtime {
     return this.loadEsmModule(modulePath, query);
   }
 
-  private async loadCjsAsEsm(
+  private loadCjsAsEsm(
     from: Config.Path,
     modulePath: Config.Path,
     context: VMContext,
@@ -483,13 +483,7 @@ class Runtime {
       {context, identifier: modulePath},
     );
 
-    await module.link(() => {
-      throw new Error('This should never happen');
-    });
-
-    await module.evaluate();
-
-    return module;
+    return evaluateSyntheticModule(module);
   }
 
   requireModule<T = unknown>(
@@ -1159,7 +1153,7 @@ class Runtime {
   private _importCoreModule(moduleName: string, context: VMContext) {
     const required = this._requireCoreModule(moduleName);
 
-    return new SyntheticModule(
+    const module = new SyntheticModule(
       ['default', ...Object.keys(required)],
       function () {
         // @ts-expect-error: TS doesn't know what `this` is
@@ -1172,6 +1166,8 @@ class Runtime {
       // should identifier be `node://${moduleName}`?
       {context, identifier: moduleName},
     );
+
+    return evaluateSyntheticModule(module);
   }
 
   private _getMockedNativeModule(): typeof nativeModule.Module {
@@ -1667,7 +1663,7 @@ class Runtime {
     return {...this.getGlobalsFromEnvironment(), jest};
   }
 
-  private async getGlobalsForEsm(
+  private getGlobalsForEsm(
     from: Config.Path,
     context: VMContext,
   ): Promise<VMModule> {
@@ -1695,13 +1691,7 @@ class Runtime {
       {context, identifier: '@jest/globals'},
     );
 
-    await module.link(() => {
-      throw new Error('This should never happen');
-    });
-
-    await module.evaluate();
-
-    return module;
+    return evaluateSyntheticModule(module);
   }
 
   private getGlobalsFromEnvironment(): JestGlobals {
@@ -1753,4 +1743,14 @@ function notEmpty<T>(value: T | null | undefined): value is T {
   return value !== null && value !== undefined;
 }
 
+async function evaluateSyntheticModule(module: SyntheticModule) {
+  await module.link(() => {
+    throw new Error('This should never happen');
+  });
+
+  await module.evaluate();
+
+  return module;
+}
+
 export = Runtime;