feat: allow opening multiple html reporters and trace viewers (#17636)

This makes `HttpServer` accept `preferredPort` option that will first
try to listen on that port, and if that port is already in use, listen
on some available port instead.

Fixes #17201.

packages/playwright-core/src/grid/gridServer.ts

@@ -393,7 +393,7 @@ export class GridServer {
   }
 
   async start(port?: number) {
-    await this._server.start(port);
+    await this._server.start({ port });
   }
 
   gridURL(): string {

packages/playwright-core/src/server/trace/viewer/traceViewer.ts

@@ -26,7 +26,7 @@ import { serverSideCallMetadata } from '../../instrumentation';
 import { createPlaywright } from '../../playwright';
 import { ProgressController } from '../../progress';
 
-export async function showTraceViewer(traceUrls: string[], browserName: string, headless = false, port?: number): Promise<BrowserContext | undefined> {
+export async function showTraceViewer(traceUrls: string[], browserName: string, headless = false, preferredPort?: number): Promise<BrowserContext | undefined> {
   for (const traceUrl of traceUrls) {
     if (!traceUrl.startsWith('http://') && !traceUrl.startsWith('https://') && !fs.existsSync(traceUrl)) {
       // eslint-disable-next-line no-console
@@ -49,7 +49,7 @@ export async function showTraceViewer(traceUrls: string[], browserName: string,
     return server.serveFile(request, response, absolutePath);
   });
 
-  const urlPrefix = await server.start(port);
+  const urlPrefix = await server.start({ preferredPort });
 
   const traceViewerPlaywright = createPlaywright('javascript', true);
   const traceViewerBrowser = isUnderTest() ? 'chromium' : browserName;

packages/playwright-core/src/utils/httpServer.ts

@@ -20,6 +20,7 @@ import path from 'path';
 import { mime, wsServer } from '../utilsBundle';
 import type { WebSocketServer } from '../utilsBundle';
 import { assert } from './';
+import { ManualPromise } from './manualPromise';
 
 export type ServerRouteHandler = (request: http.IncomingMessage, response: http.ServerResponse) => boolean;
 
@@ -51,15 +52,43 @@ export class HttpServer {
     return this._port;
   }
 
-  async start(port?: number, host = 'localhost'): Promise<string> {
+  private async _tryStart(port: number | undefined, host: string) {
+    const errorPromise = new ManualPromise();
+    const errorListener = (error: Error) => errorPromise.reject(error);
+    this._server.on('error', errorListener);
+
+    try {
+      this._server.listen(port, host);
+      await Promise.race([
+        new Promise(cb => this._server!.once('listening', cb)),
+        errorPromise,
+      ]);
+    } finally {
+      this._server.removeListener('error', errorListener);
+    }
+  }
+
+  async start(options: { port?: number, preferredPort?: number, host?: string } = {}): Promise<string> {
     assert(!this._started, 'server already started');
     this._started = true;
     this._server.on('connection', socket => {
       this._activeSockets.add(socket);
       socket.once('close', () => this._activeSockets.delete(socket));
     });
-    this._server.listen(port, host);
+
-    await new Promise(cb => this._server!.once('listening', cb));
+    const host = options.host || 'localhost';
+    if (options.preferredPort) {
+      try {
+        await this._tryStart(options.preferredPort, host);
+      } catch (e) {
+        if (!e || !e.message || !e.message.includes('EADDRINUSE'))
+          throw e;
+        await this._tryStart(undefined, host);
+      }
+    } else {
+      await this._tryStart(options.port, host);
+    }
+
     const address = this._server.address();
     assert(address, 'Could not bind server socket');
     if (!this._urlPrefix) {

packages/playwright-test/src/reporters/html.ts

@@ -149,7 +149,7 @@ function standaloneDefaultFolder(): string {
   return reportFolderFromEnv() ?? defaultReportFolder(process.cwd());
 }
 
-export async function showHTMLReport(reportFolder: string | undefined, host: string = 'localhost', port: number = 9223, testId?: string) {
+export async function showHTMLReport(reportFolder: string | undefined, host: string = 'localhost', port?: number, testId?: string) {
   const folder = reportFolder ?? standaloneDefaultFolder();
   try {
     assert(fs.statSync(folder).isDirectory());
@@ -159,7 +159,7 @@ export async function showHTMLReport(reportFolder: string | undefined, host: str
     return;
   }
   const server = startHtmlReportServer(folder);
-  let url = await server.start(port, host);
+  let url = await server.start({ port, host, preferredPort: port ? undefined : 9223 });
   console.log('');
   console.log(colors.cyan(`  Serving HTML report at ${url}. Press Ctrl+C to quit.`));
   if (testId)

tests/config/traceViewerFixtures.ts

@@ -29,7 +29,7 @@ type BaseWorkerFixtures = {
 };
 
 export type TraceViewerFixtures = {
-  showTraceViewer: (trace: string[]) => Promise<TraceViewerPage>;
+  showTraceViewer: (trace: string[], preferredPort?: number) => Promise<TraceViewerPage>;
   runAndTrace: (body: () => Promise<void>) => Promise<TraceViewerPage>;
 };
 
@@ -110,15 +110,19 @@ class TraceViewerPage {
 
 export const traceViewerFixtures: Fixtures<TraceViewerFixtures, {}, BaseTestFixtures, BaseWorkerFixtures> = {
   showTraceViewer: async ({ playwright, browserName, headless }, use) => {
-    let browser: Browser;
+    const browsers: Browser[] = [];
-    let contextImpl: any;
+    const contextImpls: any[] = [];
-    await use(async (traces: string[]) => {
+    await use(async (traces: string[], preferredPort?: number) => {
-      contextImpl = await showTraceViewer(traces, browserName, headless);
+      const contextImpl = await showTraceViewer(traces, browserName, headless, preferredPort);
-      browser = await playwright.chromium.connectOverCDP(contextImpl._browser.options.wsEndpoint);
+      const browser = await playwright.chromium.connectOverCDP(contextImpl._browser.options.wsEndpoint);
+      browsers.push(browser);
+      contextImpls.push(contextImpl);
       return new TraceViewerPage(browser.contexts()[0].pages()[0]);
     });
-    await browser?.close();
+    for (const browser of browsers)
-    await contextImpl?._browser.close();
+      await browser.close();
+    for (const contextImpl of contextImpls)
+      await contextImpl._browser.close();
   },
 
   runAndTrace: async ({ context, showTraceViewer }, use, testInfo) => {

tests/library/trace-viewer.spec.ts

@@ -78,6 +78,14 @@ test('should show empty trace viewer', async ({ showTraceViewer }, testInfo) =>
   await expect(traceViewer.page).toHaveTitle('Playwright Trace Viewer');
 });
 
+test('should open two trace viewers', async ({ showTraceViewer }, testInfo) => {
+  const preferredPort = testInfo.workerIndex + 48321;
+  const traceViewer1 = await showTraceViewer([testInfo.outputPath()], preferredPort);
+  await expect(traceViewer1.page).toHaveTitle('Playwright Trace Viewer');
+  const traceViewer2 = await showTraceViewer([testInfo.outputPath()], preferredPort);
+  await expect(traceViewer2.page).toHaveTitle('Playwright Trace Viewer');
+});
+
 test('should open simple trace viewer', async ({ showTraceViewer }) => {
   const traceViewer = await showTraceViewer([traceFile]);
   await expect(traceViewer.actionTitles).toHaveText([