fix(screencast): auto-save video when page closes without stop

[sarang-code2]

Closes #41608

Problem

When using page.screencast.start({ path: 'video.webm' }), if the page closes before page.screencast.stop() is called, the video file is never saved to disk. The server already stops the recording gracefully, but the client never calls artifact.saveAs() to write the file.

This makes it impossible to record a video showing "the window closing when a button is pressed."

Solution

Listen for Events.Page.Close in the client-side Screencast constructor. When the page closes while a recording is active (with a path option), automatically save the artifact to the specified path.

Changes:

• packages/playwright-core/src/client/screencast.ts — Register a one-time Page.Close listener that auto-saves the artifact
• tests/library/screencast.spec.ts — Add test verifying auto-save on page close

Usage

await page.screencast.start({ path: 'video.webm' });
await page.getByRole('button', { name: 'close' }).click(); // closes the page
// video.webm is now automatically saved!

[sarang-code2]

@microsoft-github-policy-service agree