test(webkit): screenshot webgl canvas after drawing buffer resize

packages/playwright-core/src/tools/backend/tab.ts

@@ -137,7 +137,7 @@ export class Tab extends EventEmitter<TabEventsInterface> {
       eventsHelper.addEventListener(p, 'dialog', dialog => this._dialogShown(dialog)),
       eventsHelper.addEventListener(p, 'dialogclosed', dialog => this._dialogClosed(dialog)),
       eventsHelper.addEventListener(p, 'download', download => {
-        void this._downloadStarted(download);
+        this._downloadStarted(download).catch(e => debug('pw:tools:error')(e));
       }),
     ];
     // eslint-disable-next-line no-restricted-syntax

tests/mcp/files.spec.ts

@@ -198,6 +198,49 @@ test('navigating to download link emits download', async ({ startClient, server,
   });
 });
 
+test('closing browser during download does not crash the server', async ({ startClient, server }, testInfo) => {
+  // Persistent Chromium on macOS does not quit while a download is in progress.
+  const { client } = await startClient({
+    config: { outputDir: testInfo.outputPath('output'), browser: { isolated: true } },
+  });
+
+  server.setContent('/', `<a href="/download" download="test.txt">Download</a>`, 'text/html');
+  server.setRoute('/download', (req, res) => {
+    res.writeHead(200, {
+      'Content-Type': 'application/octet-stream',
+      'Content-Disposition': 'attachment; filename=test.txt',
+    });
+    // Never finish the response so that the download stays in progress.
+    res.write('a'.repeat(4096));
+  });
+
+  await client.callTool({
+    name: 'browser_navigate',
+    arguments: { url: server.PREFIX },
+  });
+  let events = parseResponse(await client.callTool({
+    name: 'browser_click',
+    arguments: { element: 'Download link', target: 'e2' },
+  })).events ?? '';
+  await expect.poll(async () => {
+    events += parseResponse(await client.callTool({ name: 'browser_snapshot' })).events ?? '';
+    return events;
+  }).toContain('- Downloading file test.txt ...');
+
+  expect(await client.callTool({ name: 'browser_close' })).toHaveResponse({
+    result: expect.stringContaining('No open tabs'),
+  });
+  // Give the pending download a chance to fail after the browser is gone.
+  await new Promise(f => setTimeout(f, 1000));
+
+  expect(await client.callTool({
+    name: 'browser_navigate',
+    arguments: { url: server.PREFIX },
+  })).toHaveResponse({
+    snapshot: expect.stringContaining(`- link "Download" [ref=e2]`),
+  });
+});
+
 test('file upload restricted to roots by default', async ({ startClient, server }, testInfo) => {
   const rootDir = testInfo.outputPath('workspace');
   await fs.mkdir(rootDir, { recursive: true });

tests/page/page-screenshot.spec.ts

@@ -401,6 +401,31 @@ it.describe('page screenshot', () => {
     expect(screenshot).toMatchSnapshot('screenshot-webgl.png');
   });
 
+  it('should capture webgl canvas after its drawing buffer is resized', async ({ page, browserName, platform }) => {
+    it.info().annotations.push({ type: 'issue', description: 'https://github.com/microsoft/playwright/issues/42885' });
+    it.skip(browserName === 'webkit' && platform === 'darwin' && os.arch() === 'x64', 'WebGL is not available on Intel macOS - https://bugs.webkit.org/show_bug.cgi?id=278277');
+
+    await page.setViewportSize({ width: 200, height: 200 });
+    await page.setContent(`<body style="margin:0"><div style="width:100px;height:100px;background:rgb(0,255,0)"></div></body>`);
+    const expected = await page.screenshot();
+
+    await page.setContent(`<body style="margin:0"><canvas style="width:100px;height:100px"></canvas><script>
+      const gl = document.querySelector('canvas').getContext('webgl');
+      window.draw = size => {
+        gl.canvas.width = size;
+        gl.canvas.height = size;
+        gl.viewport(0, 0, size, size);
+        gl.clearColor(0, 1, 0, 1);
+        gl.clear(gl.COLOR_BUFFER_BIT);
+      };
+      draw(100);
+    </script></body>`);
+    await rafraf(page);
+    await page.evaluate(() => (window as any).draw(50));
+    await rafraf(page);
+    expect(comparePNGs(await page.screenshot(), expected)).toBe(null);
+  });
+
   it('should work for translateZ', async ({ page, server }) => {
     await page.setViewportSize({ width: 500, height: 500 });
     await page.goto(server.PREFIX + '/screenshots/translateZ.html');