Add mock test for release notes

ts/test-mock/release-notes/release_notes_test.ts

@@ -0,0 +1,57 @@
+// Copyright 2025 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import createDebug from 'debug';
+import { assert } from 'chai';
+
+import type { App } from '../playwright';
+import { Bootstrap } from '../bootstrap';
+import { MINUTE } from '../../util/durations';
+
+import { SIGNAL_ACI } from '../../types/SignalConversation';
+
+export const debug = createDebug('mock:test:releaseNotes');
+
+describe('release notes', function (this: Mocha.Suite) {
+  let bootstrap: Bootstrap;
+  let app: App;
+  let nextApp: App;
+
+  this.timeout(MINUTE);
+  beforeEach(async () => {
+    bootstrap = new Bootstrap();
+    await bootstrap.init();
+
+    app = await bootstrap.link();
+  });
+
+  afterEach(async function (this: Mocha.Context) {
+    if (!bootstrap) {
+      return;
+    }
+
+    if (nextApp) {
+      await bootstrap.maybeSaveLogs(this.currentTest, nextApp);
+    }
+    await nextApp?.close();
+    await bootstrap.teardown();
+  });
+
+  it('shows release notes', async () => {
+    const firstWindow = await app.getWindow();
+
+    await firstWindow.evaluate('window.SignalCI.resetReleaseNotesFetcher()');
+
+    await app.close();
+
+    nextApp = await bootstrap.startApp();
+
+    const secondWindow = await nextApp.getWindow();
+
+    const leftPane = secondWindow.locator('#LeftPane');
+    const releaseNoteConversation = leftPane.getByTestId(SIGNAL_ACI);
+    await releaseNoteConversation.waitFor();
+
+    assert.isTrue(await releaseNoteConversation.isVisible());
+  });
+});