feat: support WebAssembly (Wasm) imports in ESM modules

e2e/__tests__/nativeEsmWasm.test.ts

@@ -0,0 +1,23 @@
+/**
+ * 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 {resolve} from 'path';
+import {json as runJest} from '../runJest';
+
+const DIR = resolve(__dirname, '../native-esm-wasm');
+
+test('runs WASM test with native ESM', () => {
+  const {exitCode, json} = runJest(DIR, [], {
+    nodeOptions:
+      '--experimental-vm-modules --experimental-wasm-modules --no-warnings',
+  });
+
+  expect(exitCode).toBe(0);
+
+  expect(json.numTotalTests).toBe(1);
+  expect(json.numPassedTests).toBe(1);
+});

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

@@ -0,0 +1,12 @@
+/**
+ * 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 {getAnswer} from '../answer';
+
+test('test answer', () => {
+  expect(getAnswer()).toBe(42);
+});

e2e/native-esm-wasm/answer.js

@@ -0,0 +1,13 @@
+/**
+ * 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 * as wasm from './answer.wasm';
+
+export function getAnswer() {
+  const ret = wasm.getAnswer();
+  return ret;
+}

e2e/native-esm-wasm/package.json

@@ -0,0 +1,8 @@
+{
+  "type": "module",
+  "name": "native-esm-wasm",
+  "jest": {
+    "testEnvironment": "node",
+    "transform": {}
+  }
+}

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

@@ -258,7 +258,7 @@ test('imports from "data:text/javascript" URI with invalid data fail', async ()
 test('imports from "data:application/wasm" URI not supported', async () => {
   await expect(() =>
     import('data:application/wasm,96cafe00babe'),
-  ).rejects.toThrow('WASM is currently not supported');
+  ).rejects.toThrow('WASM in data URLs is currently not supported');
 });
 
 test('supports imports from "data:application/json" URI', async () => {

packages/jest-runtime/src/index.ts

@@ -398,9 +398,12 @@ export default class Runtime {
 
   // unstable as it should be replaced by https://github.com/nodejs/modules/issues/393, and we don't want people to use it
   unstable_shouldLoadAsEsm(path: string): boolean {
-    return Resolver.unstable_shouldLoadAsEsm(
-      path,
-      this._config.extensionsToTreatAsEsm,
+    return (
+      path.endsWith('wasm') ||
+      Resolver.unstable_shouldLoadAsEsm(
+        path,
+        this._config.extensionsToTreatAsEsm,
+      )
     );
   }
 
@@ -441,6 +444,15 @@ export default class Runtime {
         'Promise initialization should be sync - please report this bug to Jest!',
       );
 
+      if (modulePath.endsWith('wasm')) {
+        const wasm = this._importWasmModule(modulePath, context);
+
+        this._esmoduleRegistry.set(cacheKey, wasm);
+
+        transformResolve();
+        return wasm;
+      }
+
       if (this._resolver.isCoreModule(modulePath)) {
         const core = this._importCoreModule(modulePath, context);
         this._esmoduleRegistry.set(cacheKey, core);
@@ -568,7 +580,7 @@ export default class Runtime {
 
       const mime = match.groups.mime;
       if (mime === 'application/wasm') {
-        throw new Error('WASM is currently not supported');
+        throw new Error('WASM in data URLs is currently not supported');
       }
 
       const encoding = match.groups.encoding;
@@ -1640,6 +1652,49 @@ export default class Runtime {
     return evaluateSyntheticModule(module);
   }
 
+  private async _importWasmModule(moduleName: string, context: VMContext) {
+    const wasmModule = await WebAssembly.compile(fs.readFileSync(moduleName));
+
+    const exports = WebAssembly.Module.exports(wasmModule);
+    const imports = WebAssembly.Module.imports(wasmModule);
+
+    const moduleLookup: Record<string, VMModule> = {};
+    for (const {module} of imports) {
+      if (moduleLookup[module] === undefined) {
+        moduleLookup[module] = await this.linkAndEvaluateModule(
+          await this.resolveModule(module, moduleName, context),
+        );
+      }
+    }
+
+    const syntheticModule = new SyntheticModule(
+      exports.map(({name}) => name),
+      function () {
+        const importsObject: WebAssembly.Imports = {};
+        for (const {module, name} of imports) {
+          if (!importsObject[module]) {
+            importsObject[module] = {};
+          }
+          importsObject[module][name] = moduleLookup[module].namespace[name];
+        }
+        const wasmInstance = new WebAssembly.Instance(
+          wasmModule,
+          importsObject,
+        );
+        for (const {name} of exports) {
+          // @ts-expect-error: TS doesn't know what `this` is
+          this.setExport(name, wasmInstance.exports[name]);
+        }
+      },
+      {
+        context,
+        identifier: moduleName,
+      },
+    );
+
+    return syntheticModule;
+  }
+
   private _getMockedNativeModule(): typeof nativeModule.Module {
     if (this._moduleImplementation) {
       return this._moduleImplementation;