fix(compass): disable spellcheck before creating window when no network traffic COMPASS-8166 (#6853)

Author: Anemy

packages/compass-e2e-tests/tests/no-network-traffic.test.ts

@@ -65,9 +65,7 @@ describe('networkTraffic: false / Isolated Edition', function () {
     const compass = await init(this.test?.fullTitle(), {
       extraSpawnArgs: ['--no-network-traffic'],
       wrapBinary,
-      // TODO(COMPASS-8166): firstRun: true seems to result in network traffic.
-      // Probably the welcome modal.
-      firstRun: false,
+      firstRun: true,
     });
     const browser = compass.browser;
 
@@ -117,7 +115,11 @@ describe('networkTraffic: false / Isolated Edition', function () {
 
     if (
       [...connectTargets].some(
-        (target) => !/^127.0.0.1:|^\[::1\]:/.test(target)
+        // Chromium heuristically detects IPv4-only networks by attempting a UDP connection
+        // to 2001:4860:4860::8888 (the IPv6 address for Google Public DNS).
+        (target) =>
+          !/^127.0.0.1:|^\[::1\]:/.test(target) &&
+          !/^\[2001:4860:4860::8888\]:443$/.test(target)
       )
     ) {
       throw new Error(`Connected to unexpected host! ${[...connectTargets]}`);

packages/compass/src/main/application.ts

@@ -130,6 +130,20 @@ class CompassApplication {
     // Accessing isEncryptionAvailable is not allowed when app is not ready on Windows
     // https://github.com/electron/electron/issues/33640
     await app.whenReady();
+
+    const { networkTraffic } = this.preferences.getPreferences();
+
+    if (!networkTraffic) {
+      // Electron fetches spellcheck dictionaries from a CDN
+      // on all OSs expect mac (it provides a built-in spell check).
+      // Passing a non-resolving URL prevents it from fetching
+      // as there aren't any options to disable it provided.
+      // https://github.com/electron/electron/issues/22995
+      session.defaultSession.setSpellCheckerDictionaryDownloadURL(
+        'http://127.0.0.1:0/'
+      );
+    }
+
     log.info(
       mongoLogId(1_001_000_307),
       'Application',

packages/compass/src/main/window-manager.ts

@@ -140,22 +140,13 @@ function showConnectWindow(
   };
 
   debug('creating new main window:', windowOpts);
-  const { preferences } = compassApp;
-  const { networkTraffic } = preferences.getPreferences();
-
   let window: BrowserWindow | null = new BrowserWindow(windowOpts);
   if (mongodbUrl) {
     registerMongoDbUrlForBrowserWindow(window, mongodbUrl);
   }
   if (connectionId) {
     registerConnectionIdForBrowserWindow(window, connectionId);
   }
-  if (networkTraffic !== true) {
-    // https://github.com/electron/electron/issues/22995
-    window.webContents.session.setSpellCheckerDictionaryDownloadURL(
-      'http://127.0.0.1:0/'
-    );
-  }
 
   enable(window.webContents);
   const unsubscribeProxyListenerPromise = compassApp.setupProxySupport(