test: add tab source ID tests for media handler (#51095)

* test: add getMediaSourceId tab source coverage

Co-authored-by: Charles Kerr <charles@charleskerr.com>

* chore: move captureWithTabSourceId() to a shared helper

Co-authored-by: Charles Kerr <charles@charleskerr.com>

* test: improve "webContents module getMediaSourceId()" testing

Co-authored-by: Charles Kerr <charles@charleskerr.com>

---------

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Charles Kerr <charles@charleskerr.com>

spec/api-media-handler-spec.ts

@@ -4,6 +4,7 @@ import { expect } from 'chai';
 
 import * as http from 'node:http';
 
+import { captureWithTabSourceId } from './lib/media-helpers';
 import { ifit, listen } from './lib/spec-helpers';
 import { closeAllWindows } from './lib/window-helpers';
 
@@ -417,6 +418,37 @@ describe('setDisplayMediaRequestHandler', () => {
     expect(message).to.equal('Invalid state');
   });
 
+  it('works when mediaDevices.getUserMedia uses a tab source id from webContents.getMediaSourceId', async () => {
+    const sourceWindow = new BrowserWindow({ show: false });
+    const requestingWindow = new BrowserWindow({ show: false });
+    await Promise.all([sourceWindow.loadURL(serverUrl), requestingWindow.loadURL(serverUrl)]);
+
+    const sourceId = sourceWindow.webContents.getMediaSourceId(requestingWindow.webContents);
+    const { ok, message, origin, videoTrackCount } = await captureWithTabSourceId(requestingWindow, sourceId);
+
+    expect(ok).to.be.true(message);
+    expect(origin).to.equal(new URL(serverUrl).origin);
+    expect(videoTrackCount).to.equal(1);
+  });
+
+  it('rejects a tab source id when used from a different requesting webContents', async () => {
+    const sourceWindow = new BrowserWindow({ show: false });
+    const registeredRequesterWindow = new BrowserWindow({ show: false });
+    const otherRequesterWindow = new BrowserWindow({ show: false });
+    await Promise.all([
+      sourceWindow.loadURL(serverUrl),
+      registeredRequesterWindow.loadURL(serverUrl),
+      otherRequesterWindow.loadURL(serverUrl)
+    ]);
+
+    const sourceId = sourceWindow.webContents.getMediaSourceId(registeredRequesterWindow.webContents);
+    const { ok, message, origin } = await captureWithTabSourceId(otherRequesterWindow, sourceId);
+
+    expect(ok).to.be.false();
+    expect(message).to.match(/Invalid state|Error starting tab capture/);
+    expect(origin).to.equal(new URL(serverUrl).origin);
+  });
+
   it('can remove a displayMediaRequestHandler', async () => {
     const ses = session.fromPartition('' + Math.random());
 

spec/api-web-contents-spec.ts

@@ -12,6 +12,7 @@ import * as path from 'node:path';
 import { setTimeout } from 'node:timers/promises';
 import * as url from 'node:url';
 
+import { captureWithTabSourceId } from './lib/media-helpers';
 import { ifdescribe, defer, waitUntil, listen, ifit } from './lib/spec-helpers';
 import { cleanupWebContents, closeAllWindows } from './lib/window-helpers';
 
@@ -1797,9 +1798,33 @@ describe('webContents module', () => {
 
   describe('getMediaSourceId()', () => {
     afterEach(closeAllWindows);
-    it('returns a valid stream id', () => {
-      const w = new BrowserWindow({ show: false });
-      expect(w.webContents.getMediaSourceId(w.webContents)).to.be.a('string').that.is.not.empty();
+    let server: http.Server;
+    let serverUrl: string;
+
+    before(async () => {
+      server = http.createServer((req, res) => {
+        res.setHeader('Content-Type', 'text/html');
+        res.end('');
+      });
+      serverUrl = (await listen(server)).url;
+    });
+
+    after(() => {
+      server.close();
+    });
+
+    it('returns a stream id that can be used by the registered requester', async () => {
+      const sourceWindow = new BrowserWindow({ show: false });
+      const requesterWindow = new BrowserWindow({ show: false });
+      await Promise.all([sourceWindow.loadURL(serverUrl), requesterWindow.loadURL(serverUrl)]);
+
+      const streamId = sourceWindow.webContents.getMediaSourceId(requesterWindow.webContents);
+      const { ok, message, origin, videoTrackCount } = await captureWithTabSourceId(requesterWindow, streamId);
+
+      expect(streamId).to.be.a('string').that.is.not.empty();
+      expect(ok, message).to.equal(true);
+      expect(origin).to.equal(new url.URL(serverUrl).origin);
+      expect(videoTrackCount).to.equal(1);
     });
   });
 

spec/lib/media-helpers.ts

@@ -0,0 +1,39 @@
+import { BrowserWindow } from 'electron/main';
+
+export interface TabSourceCaptureResult {
+  ok: boolean;
+  href: string;
+  message?: string;
+  origin: string;
+  videoTrackCount?: number;
+}
+
+export const captureWithTabSourceId = async (
+  requestingWindow: BrowserWindow,
+  streamId: string
+): Promise<TabSourceCaptureResult> => {
+  return requestingWindow.webContents.executeJavaScript(`
+    navigator.mediaDevices.getUserMedia({
+      video: {
+        mandatory: {
+          chromeMediaSource: 'tab',
+          chromeMediaSourceId: ${JSON.stringify(streamId)},
+        },
+      },
+    }).then((stream) => {
+      const result = {
+        ok: stream instanceof MediaStream,
+        href: location.href,
+        origin: location.origin,
+        videoTrackCount: stream.getVideoTracks().length,
+      };
+      stream.getTracks().forEach((track) => track.stop());
+      return result;
+    }, (error) => ({
+      ok: false,
+      href: location.href,
+      message: error.message,
+      origin: location.origin,
+    }));
+  `);
+};