esm: add back globalPreload tests and fix failing ones

PR-URL: #48779
Backport-PR-URL: #50669
Fixes: #48778
Fixes: #48516
Refs: #46402
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Jacob Smith <jacob@frende.me>

lib/internal/main/eval_string.js

@@ -22,7 +22,7 @@ markBootstrapComplete();
 
 const source = getOptionValue('--eval');
 const print = getOptionValue('--print');
-const loadESM = getOptionValue('--import').length > 0;
+const loadESM = getOptionValue('--import').length > 0 || getOptionValue('--experimental-loader').length > 0;
 if (getOptionValue('--input-type') === 'module')
   evalModule(source, print);
 else

lib/internal/modules/esm/hooks.js

@@ -10,6 +10,7 @@ const {
   Promise,
   SafeSet,
   StringPrototypeSlice,
+  StringPrototypeStartsWith,
   StringPrototypeToUpperCase,
   globalThis,
 } = primordials;
@@ -30,6 +31,7 @@ const {
   ERR_INVALID_RETURN_PROPERTY_VALUE,
   ERR_INVALID_RETURN_VALUE,
   ERR_LOADER_CHAIN_INCOMPLETE,
+  ERR_UNKNOWN_BUILTIN_MODULE,
   ERR_WORKER_UNSERIALIZABLE_ERROR,
 } = require('internal/errors').codes;
 const { URL } = require('internal/url');
@@ -520,14 +522,14 @@ class HooksProxy {
     this.#worker.on('exit', process.exit);
   }
 
-  #waitForWorker() {
+  waitForWorker() {
     if (!this.#isReady) {
       const { kIsOnline } = require('internal/worker');
       if (!this.#worker[kIsOnline]) {
         debug('wait for signal from worker');
         AtomicsWait(this.#lock, WORKER_TO_MAIN_THREAD_NOTIFICATION, 0);
         const response = this.#worker.receiveMessageSync();
-        if (response.message.status === 'exit') { return; }
+        if (response == null || response.message.status === 'exit') { return; }
         const { preloadScripts } = this.#unwrapMessage(response);
         this.#executePreloadScripts(preloadScripts);
       }
@@ -537,7 +539,7 @@ class HooksProxy {
   }
 
   async makeAsyncRequest(method, ...args) {
-    this.#waitForWorker();
+    this.waitForWorker();
 
     MessageChannel ??= require('internal/worker/io').MessageChannel;
     const asyncCommChannel = new MessageChannel();
@@ -577,7 +579,7 @@ class HooksProxy {
   }
 
   makeSyncRequest(method, ...args) {
-    this.#waitForWorker();
+    this.waitForWorker();
 
     // Pass work to the worker.
     debug('post sync message to worker', { method, args });
@@ -619,35 +621,66 @@ class HooksProxy {
     }
   }
 
+  #importMetaInitializer = require('internal/modules/esm/initialize_import_meta').initializeImportMeta;
+
+  importMetaInitialize(meta, context, loader) {
+    this.#importMetaInitializer(meta, context, loader);
+  }
+
   #executePreloadScripts(preloadScripts) {
     for (let i = 0; i < preloadScripts.length; i++) {
       const { code, port } = preloadScripts[i];
       const { compileFunction } = require('vm');
       const preloadInit = compileFunction(
         code,
-        ['getBuiltin', 'port'],
+        ['getBuiltin', 'port', 'setImportMetaCallback'],
         {
           filename: '<preload>',
         },
       );
+      let finished = false;
+      let replacedImportMetaInitializer = false;
+      let next = this.#importMetaInitializer;
       const { BuiltinModule } = require('internal/bootstrap/realm');
       // Calls the compiled preload source text gotten from the hook
       // Since the parameters are named we use positional parameters
       // see compileFunction above to cross reference the names
-      FunctionPrototypeCall(
-        preloadInit,
-        globalThis,
-        // Param getBuiltin
-        (builtinName) => {
-          if (BuiltinModule.canBeRequiredByUsers(builtinName) &&
-              BuiltinModule.canBeRequiredWithoutScheme(builtinName)) {
-            return require(builtinName);
-          }
-          throw new ERR_INVALID_ARG_VALUE('builtinName', builtinName);
-        },
-        // Param port
-        port,
-      );
+      try {
+        FunctionPrototypeCall(
+          preloadInit,
+          globalThis,
+          // Param getBuiltin
+          (builtinName) => {
+            if (StringPrototypeStartsWith(builtinName, 'node:')) {
+              builtinName = StringPrototypeSlice(builtinName, 5);
+            } else if (!BuiltinModule.canBeRequiredWithoutScheme(builtinName)) {
+              throw new ERR_UNKNOWN_BUILTIN_MODULE(builtinName);
+            }
+            if (BuiltinModule.canBeRequiredByUsers(builtinName)) {
+              return require(builtinName);
+            }
+            throw new ERR_UNKNOWN_BUILTIN_MODULE(builtinName);
+          },
+          // Param port
+          port,
+          // setImportMetaCallback
+          (fn) => {
+            if (finished || typeof fn !== 'function') {
+              throw new ERR_INVALID_ARG_TYPE('fn', fn);
+            }
+            replacedImportMetaInitializer = true;
+            const parent = next;
+            next = (meta, context) => {
+              return fn(meta, context, parent);
+            };
+          },
+        );
+      } finally {
+        finished = true;
+        if (replacedImportMetaInitializer) {
+          this.#importMetaInitializer = next;
+        }
+      }
     }
   }
 }

lib/internal/modules/esm/loader.js

@@ -287,6 +287,11 @@ class DefaultModuleLoader {
     meta = importMetaInitializer(meta, context, this);
     return meta;
   }
+
+  /**
+   * No-op when no hooks have been supplied.
+   */
+  forceLoadHooks() {}
 }
 ObjectSetPrototypeOf(DefaultModuleLoader.prototype, null);
 
@@ -359,6 +364,14 @@ class CustomizedModuleLoader extends DefaultModuleLoader {
 
     return result;
   }
+
+  importMetaInitialize(meta, context) {
+    hooksProxy.importMetaInitialize(meta, context, this);
+  }
+
+  forceLoadHooks() {
+    hooksProxy.waitForWorker();
+  }
 }
 
 

lib/internal/process/esm_loader.js

@@ -36,6 +36,8 @@ module.exports = {
           parentURL,
           kEmptyObject,
         ));
+      } else {
+        esmLoader.forceLoadHooks();
       }
       await callback(esmLoader);
     } catch (err) {

test/es-module/test-esm-loader-hooks.mjs

@@ -1,6 +1,7 @@
 import { spawnPromisified } from '../common/index.mjs';
 import * as fixtures from '../common/fixtures.mjs';
 import assert from 'node:assert';
+import os from 'node:os';
 import { execPath } from 'node:process';
 import { describe, it } from 'node:test';
 
@@ -370,18 +371,119 @@ describe('Loader hooks', { concurrency: true }, () => {
     });
   });
 
-  it('should handle globalPreload returning undefined', async () => {
-    const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
-      '--no-warnings',
-      '--experimental-loader',
-      'data:text/javascript,export function globalPreload(){}',
-      fixtures.path('empty.js'),
-    ]);
+  describe('globalPreload', () => {
+    it('should handle globalPreload returning undefined', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-loader',
+        'data:text/javascript,export function globalPreload(){}',
+        fixtures.path('empty.js'),
+      ]);
 
-    assert.strictEqual(stderr, '');
-    assert.strictEqual(stdout, '');
-    assert.strictEqual(code, 0);
-    assert.strictEqual(signal, null);
+      assert.strictEqual(stderr, '');
+      assert.strictEqual(stdout, '');
+      assert.strictEqual(code, 0);
+      assert.strictEqual(signal, null);
+    });
+
+    it('should handle loading node:test', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-loader',
+        'data:text/javascript,export function globalPreload(){return `getBuiltin("node:test")()`}',
+        fixtures.path('empty.js'),
+      ]);
+
+      assert.strictEqual(stderr, '');
+      assert.match(stdout, /\n# pass 1\r?\n/);
+      assert.strictEqual(code, 0);
+      assert.strictEqual(signal, null);
+    });
+
+    it('should handle loading node:os with node: prefix', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-loader',
+        'data:text/javascript,export function globalPreload(){return `console.log(getBuiltin("node:os").arch())`}',
+        fixtures.path('empty.js'),
+      ]);
+
+      assert.strictEqual(stderr, '');
+      assert.strictEqual(stdout.trim(), os.arch());
+      assert.strictEqual(code, 0);
+      assert.strictEqual(signal, null);
+    });
+
+    // `os` is used here because it's simple and not mocked (the builtin module otherwise doesn't matter).
+    it('should handle loading builtin module without node: prefix', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-loader',
+        'data:text/javascript,export function globalPreload(){return `console.log(getBuiltin("os").arch())`}',
+        fixtures.path('empty.js'),
+      ]);
+
+      assert.strictEqual(stderr, '');
+      assert.strictEqual(stdout.trim(), os.arch());
+      assert.strictEqual(code, 0);
+      assert.strictEqual(signal, null);
+    });
+
+    it('should throw when loading node:test without node: prefix', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-loader',
+        'data:text/javascript,export function globalPreload(){return `getBuiltin("test")()`}',
+        fixtures.path('empty.js'),
+      ]);
+
+      assert.match(stderr, /ERR_UNKNOWN_BUILTIN_MODULE/);
+      assert.strictEqual(stdout, '');
+      assert.strictEqual(code, 1);
+      assert.strictEqual(signal, null);
+    });
+
+    it('should register globals set from globalPreload', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-loader',
+        'data:text/javascript,export function globalPreload(){return "this.myGlobal=4"}',
+        '--print', 'myGlobal',
+      ]);
+
+      assert.strictEqual(stderr, '');
+      assert.strictEqual(stdout.trim(), '4');
+      assert.strictEqual(code, 0);
+      assert.strictEqual(signal, null);
+    });
+
+    it('should log console.log calls returned from globalPreload', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-loader',
+        'data:text/javascript,export function globalPreload(){return `console.log("Hello from globalPreload")`}',
+        fixtures.path('empty.js'),
+      ]);
+
+      assert.strictEqual(stderr, '');
+      assert.strictEqual(stdout.trim(), 'Hello from globalPreload');
+      assert.strictEqual(code, 0);
+      assert.strictEqual(signal, null);
+    });
+
+    it('should crash if globalPreload returns code that throws', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+        '--no-warnings',
+        '--experimental-loader',
+        'data:text/javascript,export function globalPreload(){return `throw new Error("error from globalPreload")`}',
+        fixtures.path('empty.js'),
+      ]);
+
+      assert.match(stderr, /error from globalPreload/);
+      assert.strictEqual(stdout, '');
+      assert.strictEqual(code, 1);
+      assert.strictEqual(signal, null);
+    });
   });
 
   it('should be fine to call `process.removeAllListeners("beforeExit")` from the main thread', async () => {

test/es-module/test-esm-loader-mock.mjs

@@ -0,0 +1,45 @@
+// Flags: --loader ./test/fixtures/es-module-loaders/mock-loader.mjs
+import '../common/index.mjs';
+import assert from 'assert/strict';
+
+// This is provided by test/fixtures/es-module-loaders/mock-loader.mjs
+import mock from 'node:mock';
+
+mock('node:events', {
+  EventEmitter: 'This is mocked!'
+});
+
+// This resolves to node:events
+// It is intercepted by mock-loader and doesn't return the normal value
+assert.deepStrictEqual(await import('events'), Object.defineProperty({
+  __proto__: null,
+  EventEmitter: 'This is mocked!'
+}, Symbol.toStringTag, {
+  enumerable: false,
+  value: 'Module'
+}));
+
+const mutator = mock('node:events', {
+  EventEmitter: 'This is mocked v2!'
+});
+
+// It is intercepted by mock-loader and doesn't return the normal value.
+// This is resolved separately from the import above since the specifiers
+// are different.
+const mockedV2 = await import('node:events');
+assert.deepStrictEqual(mockedV2, Object.defineProperty({
+  __proto__: null,
+  EventEmitter: 'This is mocked v2!'
+}, Symbol.toStringTag, {
+  enumerable: false,
+  value: 'Module'
+}));
+
+mutator.EventEmitter = 'This is mocked v3!';
+assert.deepStrictEqual(mockedV2, Object.defineProperty({
+  __proto__: null,
+  EventEmitter: 'This is mocked v3!'
+}, Symbol.toStringTag, {
+  enumerable: false,
+  value: 'Module'
+}));