fix(electron): consistently emit ready event after app is loaded (#18972)

Fixes: https://github.com/microsoft/playwright/issues/18928

packages/playwright-core/src/server/electron/loader.ts

@@ -32,6 +32,25 @@ for (const arg of chromiumSwitches) {
   app.getAppPath = () => path.dirname(appPath);
 }
 
-(globalThis as any).__playwright_run = () => {
+let launchInfoEventPayload: any;
+app.on('ready', launchInfo => launchInfoEventPayload = launchInfo);
+
+(globalThis as any).__playwright_run = async () => {
+  // Wait for app to be ready to avoid browser initialization races.
+  await app.whenReady();
+
+  // Override isReady pipeline.
+  let isReady = false;
+  let whenReadyCallback: () => void;
+  const whenReadyPromise = new Promise<void>(f => whenReadyCallback = f);
+  app.isReady = () => isReady;
+  app.whenReady = () => whenReadyPromise;
+
   require(appPath);
+
+  // Trigger isReady.
+  isReady = true;
+  whenReadyCallback!();
+  app.emit('will-finish-launching');
+  app.emit('ready', launchInfoEventPayload);
 };

tests/electron/electron-app-ready-event.js

@@ -0,0 +1,12 @@
+const { app } = require('electron');
+
+globalThis.__playwrightLog = [];
+
+globalThis.__playwrightLog.push(`isReady == ${app.isReady()}`);
+app.whenReady().then(() => {
+  globalThis.__playwrightLog.push(`whenReady resolved`);
+  globalThis.__playwrightLog.push(`isReady == ${app.isReady()}`);
+});
+
+app.on('will-finish-launching', () => globalThis.__playwrightLog.push('will-finish-launching fired'));
+app.on('ready', () => globalThis.__playwrightLog.push('ready fired'));

tests/electron/electron-app.spec.ts

@@ -33,6 +33,24 @@ test('should fire close event', async ({ playwright }) => {
   expect(events.join('|')).toBe('context|application');
 });
 
+test('should dispatch ready event', async ({ playwright }) => {
+  const electronApp = await playwright._electron.launch({
+    args: [path.join(__dirname, 'electron-app-ready-event.js')],
+  });
+  try {
+    const events = await electronApp.evaluate(() => globalThis.__playwrightLog);
+    expect(events).toEqual([
+      'isReady == false',
+      'will-finish-launching fired',
+      'ready fired',
+      'whenReady resolved',
+      'isReady == true',
+    ]);
+  } finally {
+    await electronApp.close();
+  }
+});
+
 test('should script application', async ({ electronApp }) => {
   const appPath = await electronApp.evaluate(async ({ app }) => app.getAppPath());
   expect(appPath).toBe(path.resolve(__dirname));