chore: remove support for esm loader with process restart (#35732)

packages/playwright/src/common/configLoader.ts

@@ -17,7 +17,6 @@
 import fs from 'fs';
 import path from 'path';
 
-import { gracefullyProcessExitDoNotHang } from 'playwright-core/lib/utils';
 import { isRegExp } from 'playwright-core/lib/utils';
 
 import { requireOrImport, setSingleTSConfig, setTransformConfig } from '../transform/transform';
@@ -25,7 +24,6 @@ import { errorWithFile, fileIsModule } from '../util';
 import { FullConfigInternal } from './config';
 import { configureESMLoader, configureESMLoaderTransformConfig, registerESMLoader } from './esmLoaderHost';
 import { addToCompilationCache } from '../transform/compilationCache';
-import { execArgvWithExperimentalLoaderOptions, execArgvWithoutExperimentalLoaderOptions } from '../transform/esmUtils';
 
 import type { ConfigLocation } from './config';
 import type { ConfigCLIOverrides, SerializedConfig } from './ipc';
@@ -102,6 +100,14 @@ async function loadUserConfig(location: ConfigLocation): Promise<Config> {
 }
 
 export async function loadConfig(location: ConfigLocation, overrides?: ConfigCLIOverrides, ignoreProjectDependencies = false, metadata?: Config['metadata']): Promise<FullConfigInternal> {
+  // 0. Setup ESM loader if needed.
+  if (!registerESMLoader()) {
+    // In Node.js < 18, complain if the config file is ESM. Historically, we would restart
+    // the process with --loader, but now we require newer Node.js.
+    if (location.resolvedConfigFile && fileIsModule(location.resolvedConfigFile))
+      throw errorWithFile(location.resolvedConfigFile, `Playwright requires Node.js 18 or higher to load esm modules. Please update your version of Node.js.`);
+  }
+
   // 1. Setup tsconfig; configure ESM loader with tsconfig and compilation cache.
   setSingleTSConfig(overrides?.tsconfig);
   await configureESMLoader();
@@ -359,57 +365,11 @@ function resolveConfigFile(configFileOrDirectory: string): string | undefined {
   return configFileOrDirectory!;
 }
 
-export async function loadConfigFromFileRestartIfNeeded(configFile: string | undefined, overrides?: ConfigCLIOverrides, ignoreDeps?: boolean): Promise<FullConfigInternal | null> {
+export async function loadConfigFromFile(configFile: string | undefined, overrides?: ConfigCLIOverrides, ignoreDeps?: boolean): Promise<FullConfigInternal> {
-  const location = resolveConfigLocation(configFile);
+  return await loadConfig(resolveConfigLocation(configFile), overrides, ignoreDeps);
-  if (restartWithExperimentalTsEsm(location.resolvedConfigFile))
-    return null;
-  return await loadConfig(location, overrides, ignoreDeps);
 }
 
 export async function loadEmptyConfigForMergeReports() {
   // Merge reports is "different" for no good reason. It should not pick up local config from the cwd.
   return await loadConfig({ configDir: process.cwd() });
 }
-
-export function restartWithExperimentalTsEsm(configFile: string | undefined, force: boolean = false): boolean {
-  // Opt-out switch.
-  if (process.env.PW_DISABLE_TS_ESM)
-    return false;
-
-  // There are two esm loader APIs:
-  // - Older API that needs a process restart. Available in Node 16, 17, and non-latest 18, 19 and 20.
-  // - Newer API that works in-process. Available in Node 21+ and latest 18, 19 and 20.
-
-  // First check whether we have already restarted with the ESM loader from the older API.
-  if ((globalThis as any).__esmLoaderPortPreV20) {
-    // clear execArgv after restart, so that childProcess.fork in user code does not inherit our loader.
-    process.execArgv = execArgvWithoutExperimentalLoaderOptions();
-    return false;
-  }
-
-  // Now check for the newer API presence.
-  if (!require('node:module').register) {
-    // With older API requiring a process restart, do so conditionally on the config.
-    const configIsModule = !!configFile && fileIsModule(configFile);
-    if (!force && !configIsModule)
-      return false;
-
-    const innerProcess = (require('child_process') as typeof import('child_process')).fork(require.resolve('../../cli'), process.argv.slice(2), {
-      env: {
-        ...process.env,
-        PW_TS_ESM_LEGACY_LOADER_ON: '1',
-      },
-      execArgv: execArgvWithExperimentalLoaderOptions(),
-    });
-
-    innerProcess.on('close', (code: number | null) => {
-      if (code !== 0 && code !== null)
-        gracefullyProcessExitDoNotHang(code);
-    });
-    return true;
-  }
-
-  // With the newer API, always enable the ESM loader, because it does not need a restart.
-  registerESMLoader();
-  return false;
-}

packages/playwright/src/common/esmLoaderHost.ts

@@ -21,21 +21,27 @@ import { PortTransport } from '../transform/portTransport';
 import { singleTSConfig, transformConfig } from '../transform/transform';
 
 let loaderChannel: PortTransport | undefined;
-// Node.js < 20
-if ((globalThis as any).__esmLoaderPortPreV20)
-  loaderChannel = createPortTransport((globalThis as any).__esmLoaderPortPreV20);
 
-// Node.js >= 20
-export let esmLoaderRegistered = false;
 export function registerESMLoader() {
+  // Opt-out switch.
+  if (process.env.PW_DISABLE_TS_ESM)
+    return true;
+
+  if (loaderChannel)
+    return true;
+
+  const register = require('node:module').register;
+  if (!register)
+    return false;
+
   const { port1, port2 } = new MessageChannel();
   // register will wait until the loader is initialized.
-  require('node:module').register(url.pathToFileURL(require.resolve('../transform/esmLoader')), {
+  register(url.pathToFileURL(require.resolve('../transform/esmLoader')), {
     data: { port: port2 },
     transferList: [port2],
   });
   loaderChannel = createPortTransport(port1);
-  esmLoaderRegistered = true;
+  return true;
 }
 
 function createPortTransport(port: MessagePort) {

packages/playwright/src/common/process.ts

@@ -17,8 +17,6 @@
 import { setTimeOrigin, startProfiling, stopProfiling } from 'playwright-core/lib/utils';
 
 import { serializeError } from '../util';
-import { registerESMLoader } from './esmLoaderHost';
-import { execArgvWithoutExperimentalLoaderOptions } from '../transform/esmUtils';
 
 import type { EnvProducedPayload, ProcessInitParams, TestInfoErrorImpl } from './ipc';
 
@@ -54,13 +52,6 @@ process.on('disconnect', () => gracefullyCloseAndExit(true));
 process.on('SIGINT', () => {});
 process.on('SIGTERM', () => {});
 
-// Clear execArgv immediately, so that the user-code does not inherit our loader.
-process.execArgv = execArgvWithoutExperimentalLoaderOptions();
-
-// Node.js >= 20
-if (process.env.PW_TS_ESM_LOADER_ON)
-  registerESMLoader();
-
 let processRunner: ProcessRunner | undefined;
 let processName: string | undefined;
 const startingEnv = { ...process.env };

packages/playwright/src/program.ts

@@ -23,7 +23,7 @@ import { program } from 'playwright-core/lib/cli/program';
 import { gracefullyProcessExitDoNotHang, startProfiling, stopProfiling } from 'playwright-core/lib/utils';
 
 import { builtInReporters, defaultReporter, defaultTimeout } from './common/config';
-import { loadConfigFromFileRestartIfNeeded, loadEmptyConfigForMergeReports, resolveConfigLocation } from './common/configLoader';
+import { loadConfigFromFile, loadEmptyConfigForMergeReports, resolveConfigLocation } from './common/configLoader';
 export { program } from 'playwright-core/lib/cli/program';
 import { prepareErrorStack } from './reporters/base';
 import { showHTMLReport } from './reporters/html';
@@ -77,9 +77,7 @@ function addClearCacheCommand(program: Command) {
   command.description('clears build and test caches');
   command.option('-c, --config <file>', `Configuration file, or a test directory with optional "playwright.config.{m,c}?{js,ts}"`);
   command.action(async opts => {
-    const config = await loadConfigFromFileRestartIfNeeded(opts.config);
+    const config = await loadConfigFromFile(opts.config);
-    if (!config)
-      return;
     const runner = new Runner(config);
     const { status } = await runner.clearCache();
     const exitCode = status === 'interrupted' ? 130 : (status === 'passed' ? 0 : 1);
@@ -102,9 +100,7 @@ function addDevServerCommand(program: Command) {
   command.description('start dev server');
   command.option('-c, --config <file>', `Configuration file, or a test directory with optional "playwright.config.{m,c}?{js,ts}"`);
   command.action(async options => {
-    const config = await loadConfigFromFileRestartIfNeeded(options.config);
+    const config = await loadConfigFromFile(options.config);
-    if (!config)
-      return;
     const runner = new Runner(config);
     const { status } = await runner.runDevServer();
     const exitCode = status === 'interrupted' ? 130 : (status === 'passed' ? 0 : 1);
@@ -161,10 +157,7 @@ async function runTests(args: string[], opts: { [key: string]: any }) {
   await startProfiling();
   const cliOverrides = overridesFromOptions(opts);
 
-  const config = await loadConfigFromFileRestartIfNeeded(opts.config, cliOverrides, opts.deps === false);
+  const config = await loadConfigFromFile(opts.config, cliOverrides, opts.deps === false);
-  if (!config)
-    return;
-
   config.cliArgs = args;
   config.cliGrep = opts.grep as string | undefined;
   config.cliOnlyChanged = opts.onlyChanged === true ? 'HEAD' : opts.onlyChanged;
@@ -191,8 +184,6 @@ async function runTests(args: string[], opts: { [key: string]: any }) {
       reporter: Array.isArray(opts.reporter) ? opts.reporter : opts.reporter ? [opts.reporter] : undefined,
     });
     await stopProfiling('runner');
-    if (status === 'restarted')
-      return;
     const exitCode = status === 'interrupted' ? 130 : (status === 'passed' ? 0 : 1);
     gracefullyProcessExitDoNotHang(exitCode);
     return;
@@ -211,8 +202,6 @@ async function runTests(args: string[], opts: { [key: string]: any }) {
         }
     );
     await stopProfiling('runner');
-    if (status === 'restarted')
-      return;
     const exitCode = status === 'interrupted' ? 130 : (status === 'passed' ? 0 : 1);
     gracefullyProcessExitDoNotHang(exitCode);
     return;
@@ -229,8 +218,6 @@ async function runTestServer(opts: { [key: string]: any }) {
   const host = opts.host || 'localhost';
   const port = opts.port ? +opts.port : 0;
   const status = await testServer.runTestServer(opts.config, { }, { host, port });
-  if (status === 'restarted')
-    return;
   const exitCode = status === 'interrupted' ? 130 : (status === 'passed' ? 0 : 1);
   gracefullyProcessExitDoNotHang(exitCode);
 }
@@ -240,9 +227,7 @@ export async function withRunnerAndMutedWrite(configFile: string | undefined, ca
   const stdoutWrite = process.stdout.write.bind(process.stdout);
   process.stdout.write = ((a: any, b: any, c: any) => process.stderr.write(a, b, c)) as any;
   try {
-    const config = await loadConfigFromFileRestartIfNeeded(configFile);
+    const config = await loadConfigFromFile(configFile);
-    if (!config)
-      return;
     const runner = new Runner(config);
     const result = await callback(runner);
     stdoutWrite(JSON.stringify(result, undefined, 2), () => {
@@ -265,9 +250,7 @@ async function listTestFiles(opts: { [key: string]: any }) {
 
 async function mergeReports(reportDir: string | undefined, opts: { [key: string]: any }) {
   const configFile = opts.config;
-  const config = configFile ? await loadConfigFromFileRestartIfNeeded(configFile) : await loadEmptyConfigForMergeReports();
+  const config = configFile ? await loadConfigFromFile(configFile) : await loadEmptyConfigForMergeReports();
-  if (!config)
-    return;
 
   const dir = path.resolve(process.cwd(), reportDir || '');
   const dirStat = await fs.promises.stat(dir).catch(e => null);

packages/playwright/src/runner/processHost.ts

@@ -20,9 +20,6 @@ import { EventEmitter } from 'events';
 import { assert, timeOrigin } from 'playwright-core/lib/utils';
 import { debug } from 'playwright-core/lib/utilsBundle';
 
-import { esmLoaderRegistered } from '../common/esmLoaderHost';
-import { execArgvWithExperimentalLoaderOptions } from '../transform/esmUtils';
-
 import type { EnvProducedPayload, ProcessInitParams } from '../common/ipc';
 import type { ProtocolResponse } from '../common/process';
 
@@ -58,7 +55,6 @@ export class ProcessHost extends EventEmitter {
       env: {
         ...process.env,
         ...this._extraEnv,
-        ...(esmLoaderRegistered ? { PW_TS_ESM_LOADER_ON: '1' } : {}),
       },
       stdio: [
         'ignore',
@@ -66,7 +62,6 @@ export class ProcessHost extends EventEmitter {
         (options.onStdErr && !process.env.PW_RUNNER_DEBUG) ? 'pipe' : 'inherit',
         'ipc',
       ],
-      ...(process.env.PW_TS_ESM_LEGACY_LOADER_ON ? { execArgv: execArgvWithExperimentalLoaderOptions() } : {}),
     });
     this.process.on('exit', async (code, signal) => {
       this._processDidExit = true;

packages/playwright/src/runner/testServer.ts

@@ -24,7 +24,7 @@ import { open } from 'playwright-core/lib/utilsBundle';
 import { createErrorCollectingReporter, createReporterForTestServer, createReporters } from './reporters';
 import { SigIntWatcher } from './sigIntWatcher';
 import { TestRun, createApplyRebaselinesTask, createClearCacheTask, createGlobalSetupTasks, createListFilesTask, createLoadTask, createReportBeginTask, createRunTestsTasks, createStartDevServerTask, runTasks, runTasksDeferCleanup } from './tasks';
-import { loadConfig, resolveConfigLocation, restartWithExperimentalTsEsm } from '../common/configLoader';
+import { loadConfig, resolveConfigLocation } from '../common/configLoader';
 import { Watcher } from '../fsWatcher';
 import { baseFullConfig } from '../isomorphic/teleReceiver';
 import { addGitCommitInfoPlugin } from '../plugins/gitCommitInfoPlugin';
@@ -435,7 +435,7 @@ export class TestServerDispatcher implements TestServerInterface {
   }
 }
 
-export async function runUIMode(configFile: string | undefined, configCLIOverrides: ConfigCLIOverrides, options: TraceViewerServerOptions & TraceViewerRedirectOptions): Promise<reporterTypes.FullResult['status'] | 'restarted'> {
+export async function runUIMode(configFile: string | undefined, configCLIOverrides: ConfigCLIOverrides, options: TraceViewerServerOptions & TraceViewerRedirectOptions): Promise<reporterTypes.FullResult['status']> {
   const configLocation = resolveConfigLocation(configFile);
   return await innerRunTestServer(configLocation, configCLIOverrides, options, async (server: HttpServer, cancelPromise: ManualPromise<void>) => {
     await installRootRedirect(server, [], { ...options, webApp: 'uiMode.html' });
@@ -469,7 +469,7 @@ async function installedChromiumChannelForUI(configLocation: ConfigLocation, con
   return undefined;
 }
 
-export async function runTestServer(configFile: string | undefined, configCLIOverrides: ConfigCLIOverrides, options: { host?: string, port?: number }): Promise<reporterTypes.FullResult['status'] | 'restarted'> {
+export async function runTestServer(configFile: string | undefined, configCLIOverrides: ConfigCLIOverrides, options: { host?: string, port?: number }): Promise<reporterTypes.FullResult['status']> {
   const configLocation = resolveConfigLocation(configFile);
   return await innerRunTestServer(configLocation, configCLIOverrides, options, async server => {
     // eslint-disable-next-line no-console
@@ -477,9 +477,7 @@ export async function runTestServer(configFile: string | undefined, configCLIOve
   });
 }
 
-async function innerRunTestServer(configLocation: ConfigLocation, configCLIOverrides: ConfigCLIOverrides, options: { host?: string, port?: number }, openUI: (server: HttpServer, cancelPromise: ManualPromise<void>) => Promise<void>): Promise<reporterTypes.FullResult['status'] | 'restarted'> {
+async function innerRunTestServer(configLocation: ConfigLocation, configCLIOverrides: ConfigCLIOverrides, options: { host?: string, port?: number }, openUI: (server: HttpServer, cancelPromise: ManualPromise<void>) => Promise<void>): Promise<reporterTypes.FullResult['status']> {
-  if (restartWithExperimentalTsEsm(undefined, true))
-    return 'restarted';
   const testServer = new TestServer(configLocation, configCLIOverrides);
   const cancelPromise = new ManualPromise<void>();
   const sigintWatcher = new SigIntWatcher();

packages/playwright/src/runner/watchMode.ts

@@ -25,7 +25,6 @@ import { colors } from 'playwright-core/lib/utils';
 import { separator, terminalScreen } from '../reporters/base';
 import { enquirer } from '../utilsBundle';
 import { TestServerDispatcher } from './testServer';
-import { restartWithExperimentalTsEsm } from '../common/configLoader';
 import { TeleSuiteUpdater } from '../isomorphic/teleSuiteUpdater';
 import { TestServerConnection  } from '../isomorphic/testServerConnection';
 
@@ -73,10 +72,7 @@ interface WatchModeOptions {
   grep?: string;
 }
 
-export async function runWatchModeLoop(configLocation: ConfigLocation, initialOptions: WatchModeOptions): Promise<FullResult['status'] | 'restarted'> {
+export async function runWatchModeLoop(configLocation: ConfigLocation, initialOptions: WatchModeOptions): Promise<FullResult['status']> {
-  if (restartWithExperimentalTsEsm(undefined, true))
-    return 'restarted';
-
   const options: WatchModeOptions = { ...initialOptions };
   let bufferMode = false;
 

packages/playwright/src/transform/esmLoader.ts

@@ -86,15 +86,6 @@ async function load(moduleUrl: string, context: { format?: string }, defaultLoad
 
 let transport: PortTransport | undefined;
 
-// Node.js < 20
-function globalPreload(context: { port: MessagePort }) {
-  transport = createTransport(context.port);
-  return `
-    globalThis.__esmLoaderPortPreV20 = port;
-  `;
-}
-
-// Node.js >= 20
 function initialize(data: { port: MessagePort }) {
   transport = createTransport(data?.port);
 }
@@ -132,4 +123,4 @@ function createTransport(port: MessagePort) {
 }
 
 
-module.exports = { globalPreload, initialize, load, resolve };
+module.exports = { initialize, load, resolve };

packages/playwright/src/transform/esmUtils.ts

@@ -1,33 +0,0 @@
-/**
- * Copyright (c) Microsoft Corporation.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import url from 'url';
-
-const kExperimentalLoaderOptions = [
-  '--no-warnings',
-  `--experimental-loader=${url.pathToFileURL(require.resolve('playwright/lib/transform/esmLoader')).toString()}`,
-];
-
-export function execArgvWithExperimentalLoaderOptions() {
-  return [
-    ...process.execArgv,
-    ...kExperimentalLoaderOptions,
-  ];
-}
-
-export function execArgvWithoutExperimentalLoaderOptions() {
-  return process.execArgv.filter(arg => !kExperimentalLoaderOptions.includes(arg));
-}