(squash) narrate _PreventEmptyStack tests a bit more

Author: gnprice

test/widgets/app_test.dart

@@ -85,89 +85,92 @@ void main() {
       await prepare(tester);
       // The navigator stack should contain only a home page route.
 
+      // Log out, causing the home page to be removed from the stack.
       final future = logOutAccount(testBinding.globalStore, eg.selfAccount.id);
       await tester.pump(TestGlobalStore.removeAccountDuration);
       await future;
-      // The navigator stack should contain only a choose-account page route.
       check(testBinding.globalStore.takeDoRemoveAccountCalls())
         .single.equals(eg.selfAccount.id);
+      // The choose-account page should appear.
       check(removedRoutes).single.isA<WidgetRoute>().page.isA<HomePage>();
       check(pushedRoutes).single.isA<WidgetRoute>().page.isA<ChooseAccountPage>();
     });
 
     testWidgets('push route when popping last route on stack', (tester) async {
+      // Set up the loading of per-account data to fail.
       await testBinding.globalStore.insertAccount(eg.selfAccount.toCompanion(false));
-
       testBinding.globalStore.loadPerAccountDuration = Duration.zero;
       testBinding.globalStore.loadPerAccountException = eg.apiExceptionUnauthorized();
       await prepare(tester);
       // The navigator stack should contain only a home page route.
 
-      await tester.pump(Duration.zero); // got the error
+      // Await the failed load, causing the home page to be removed
+      // and an error dialog pushed in its place.
+      await tester.pump(Duration.zero);
       await tester.pump(TestGlobalStore.removeAccountDuration);
-      // The navigator stack should contain only a dialog route.
-      // The home page route was removed because of account logout.
       check(testBinding.globalStore.takeDoRemoveAccountCalls())
         .single.equals(eg.selfAccount.id);
       check(removedRoutes).single.isA<WidgetRoute>().page.isA<HomePage>();
       check(poppedRoutes).isEmpty();
       check(pushedRoutes).single.isA<DialogRoute<void>>();
       pushedRoutes.clear();
 
+      // Dismiss the error dialog, causing it to be popped from the stack.
       await tester.tap(find.byWidget(checkErrorDialog(tester,
         expectedTitle: 'Could not connect',
         expectedMessage:
           'Your account at ${eg.selfAccount.realmUrl} could not be authenticated.'
           ' Please try logging in again or use another account.')));
-      // The navigator stack should contain only a choose-account page route.
-      // After the error dialog is dismissed, it becomes empty,
-      // so a choose-account page route should be pushed.
+      // The choose-account page should appear, because the error dialog
+      // was the only route remaining.
       check(poppedRoutes).single.isA<DialogRoute<void>>();
       check(pushedRoutes).single.isA<WidgetRoute>().page.isA<ChooseAccountPage>();
     });
 
     testWidgets('do not push route to non-empty navigator stack', (tester) async {
-      await testBinding.globalStore.insertAccount(eg.selfAccount.toCompanion(false));
-
-      // Set up long enough loading time to later navigate to the choose-account
-      // page from the loading page via the "Try another account" button.
+      // Set up the loading of per-account data to fail, but only after a
+      // long enough time for the "Try another account" button to appear.
       const loadPerAccountDuration = Duration(seconds: 30);
       assert(loadPerAccountDuration > kTryAnotherAccountWaitPeriod);
+      await testBinding.globalStore.insertAccount(eg.selfAccount.toCompanion(false));
       testBinding.globalStore.loadPerAccountDuration = loadPerAccountDuration;
       testBinding.globalStore.loadPerAccountException = eg.apiExceptionUnauthorized();
       await prepare(tester);
       // The navigator stack should contain only a home page route.
 
+      // Await the "Try another account" button, and tap it.
       await tester.pump(kTryAnotherAccountWaitPeriod);
       await tester.tap(find.text('Try another account'));
-      await tester.pump(); // tap the button
+      await tester.pump();
       // The navigator stack should contain the home page route
       // and a choose-account page route.
       check(removedRoutes).isEmpty();
       check(poppedRoutes).isEmpty();
       check(pushedRoutes).single.isA<WidgetRoute>().page.isA<ChooseAccountPage>();
       pushedRoutes.clear();
 
-      await tester.pump(loadPerAccountDuration); // got the error
+      // Now await the failed load, causing the home page to be removed
+      // and an error dialog pushed, while the choose-account page remains.
+      await tester.pump(loadPerAccountDuration);
       await tester.pump(TestGlobalStore.removeAccountDuration);
-      // The navigator stack should contain the choose-account page route
-      // and a dialog route.
-      // The home page route was removed because of account logout.
       check(testBinding.globalStore.takeDoRemoveAccountCalls())
         .single.equals(eg.selfAccount.id);
       check(removedRoutes).single.isA<WidgetRoute>().page.isA<HomePage>();
       check(poppedRoutes).isEmpty();
       check(pushedRoutes).single.isA<DialogRoute<void>>();
       pushedRoutes.clear();
+      // The navigator stack should now contain the choose-account page route
+      // and the dialog route.
 
+      // Dismiss the error dialog, causing it to be popped from the stack.
       await tester.tap(find.byWidget(checkErrorDialog(tester,
         expectedTitle: 'Could not connect',
         expectedMessage:
           'Your account at ${eg.selfAccount.realmUrl} could not be authenticated.'
           ' Please try logging in again or use another account.')));
-      // The navigator stack should contain only the choose-account page route.
       // No routes should be pushed after dismissing the error dialog,
-      // because the navigator stack was non-empty.
+      // because there was already another route remaining on the stack
+      // (namely the choose-account page route).
       check(poppedRoutes).single.isA<DialogRoute<void>>();
       check(pushedRoutes).isEmpty();
     });