Reduce mock test flake on CI

package.json

@@ -41,7 +41,7 @@
     "test-electron": "node ts/scripts/test-electron.js",
     "test-release": "node ts/scripts/test-release.js",
     "test-node": "cross-env LANG=en-us electron-mocha --timeout 10000 --file test/setup-test-node.js --recursive test/modules ts/test-node ts/test-both",
-    "test-mock": "mocha ts/test-mock/**/*_test.js",
+    "test-mock": "mocha --require ts/test-mock/setup-ci.js ts/test-mock/**/*_test.js",
     "test-eslint": "mocha .eslint/rules/**/*.test.js --ignore-leaks",
     "test-node-coverage": "nyc --reporter=lcov --reporter=text mocha --recursive test/modules ts/test-node ts/test-both",
     "test-lint-intl": "ts-node ./build/intl-linter/linter.ts --test",

ts/test-mock/bootstrap.ts

@@ -359,6 +359,12 @@ export class Bootstrap {
     const { logsDir } = this;
     await fs.rename(logsDir, outDir);
 
+    const page = await app?.getWindow();
+    if (process.env.TRACING) {
+      await page
+        ?.context()
+        .tracing.stop({ path: path.join(outDir, 'trace.zip') });
+    }
     if (app) {
       const window = await app.getWindow();
       const screenshot = await window.screenshot();

ts/test-mock/playwright.ts

@@ -62,13 +62,20 @@ export class App extends EventEmitter {
           SIGNAL_CI_CONFIG: this.options.config,
         },
         locale: 'en',
-        timeout: 20 * SECOND,
+        timeout: 30 * SECOND,
       });
 
       // wait for the first window to load
       await pTimeout(
         (async () => {
-          const page = await this.privApp?.firstWindow();
+          const page = await this.getWindow();
+          if (process.env.TRACING) {
+            await page.context().tracing.start({
+              name: 'tracing',
+              screenshots: true,
+              snapshots: true,
+            });
+          }
           await page?.waitForLoadState('load');
         })(),
         20 * SECOND

ts/test-mock/setup-ci.ts

@@ -0,0 +1,25 @@
+// Copyright 2023 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import createDebug from 'debug';
+
+import { Bootstrap } from './bootstrap';
+
+const debug = createDebug('mock:test:setup-ci');
+
+// Sadly, we can reduce flakiness in CI by launching the app once first
+export async function mochaGlobalSetup(): Promise<void> {
+  if (!process.env.CI) {
+    return;
+  }
+
+  debug('Launching app before running all tests');
+  const bootstrap = new Bootstrap();
+  await bootstrap.init();
+  const app = await bootstrap.link();
+
+  debug('Closing app before running all tests');
+  await app.close();
+  await bootstrap.teardown();
+  debug('Done');
+}