Improve the channel observer and split the tests better

test/observer/observer.dart

@@ -1,2 +1,2 @@
 export 'toast.dart';
-export 'app.dart';
+export 'system.dart';

test/observer/system.dart

@@ -0,0 +1,31 @@
+import 'package:flutter/services.dart';
+
+import '../test.dart';
+
+/// An observer for the system channel. 
+class SystemChannelObserver {
+
+  int _closeRequests = 0;  /// How many close request was recorded since the last observation.
+  int get closeRequests {
+    final numRequests = _closeRequests;
+    clearCloseRequest();
+    return numRequests;
+  } 
+
+  /// Create a new system channel observer, which automatically
+  /// unregisters any previously created observer.
+  SystemChannelObserver(WidgetTester tester) {
+    tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (call) {
+      if (call.method == 'SystemNavigator.pop') {
+        _closeRequests++;
+        return null;
+      }
+      return null;  // Ignore unimplemented method calls
+    });
+  }
+
+  /// Reset the number of recorded close requests to zero.
+  void clearCloseRequest() {
+    _closeRequests = 0;
+  }
+}

test/observer/toast.dart

@@ -3,45 +3,30 @@ import 'package:flutter/services.dart';
 import '../test.dart';
 
 /// An observer for toast messages from the flutter toast package.
-class ToastObserver {
+class ToastChannelObserver {
   /// The method channel used by the flutter toast package
   static const MethodChannel _channel = MethodChannel('PonnamKarthik/fluttertoast');
-  /// The arguments for the last requested toast message.
-  Map<String, dynamic>? lastToastMessage;
-
-  /// Create a new toast observer, which automatically
+  Map<String, dynamic>? _lastToastArguments;  /// The arguments for the last requested toast message.
+  String? get lastToastMessage {
+    final lastArguments = _lastToastArguments;
+    clearLastToast();
+    return lastArguments?['msg'] as String?;
+  }
+
+  /// Create a new toast channel observer, which automatically
   ///  unregisters any previously created observer.
-  ToastObserver(WidgetTester tester) {
+  ToastChannelObserver(WidgetTester tester) {
     tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(_channel, (call) {
       if (call.method == 'showToast') {
-        lastToastMessage = Map.castFrom(call.arguments);
+        _lastToastArguments = Map.castFrom(call.arguments);
         return null;
       }
       return null;  // Ignore unimplemented method calls
     });
   }
 
-  /// Verify that the provided [callable] shows a toast.
-  /// If provided, also verify that the toast showed the given [message].
-  /// If no toast was shown or the message doesn't match,
-  /// fail with the given [reason].
-  Future<void> expectShowsToast(Future<void> Function() callable, {String? message, String? reason}) async {
-    lastToastMessage = null;
-    await callable();
-    expect(lastToastMessage, isNotNull,
-        reason: 'Expected a toast to be shown' + (reason != null ? ': $reason' : ''));
-    if (message != null) {
-      expect(lastToastMessage!['msg'] as String?, equals(message),
-          reason: 'Expected a toast to show the expected message' + (reason != null ? ': $reason' : ''));
-    }
-  }
-
-  /// Verify that the provided [callable] doesn't show a toast.
-  /// Otherwise fail with the given [reason].
-  Future<void> expectShowsNoToast(Future<void> Function() callable, {String? reason}) async {
-    lastToastMessage = null;
-    await callable();
-    expect(lastToastMessage, isNull,
-        reason: 'Expected no toast to be shown' + (reason != null ? ': $reason' : ''));
+  /// Forget the last received toast.
+  void clearLastToast() {
+    _lastToastArguments = null;
   }
 }

test/routes/home_route_test.dart

@@ -1,4 +1,5 @@
 import 'package:back_button_interceptor/back_button_interceptor.dart';
+import 'package:sweyer/constants.dart';
 
 import '../observer/observer.dart';
 import '../test.dart';
@@ -71,74 +72,42 @@ void main() {
     });
   });
 
-  testWidgets('app shows exit confirmation toast', (WidgetTester tester) async {
+  testWidgets('app shows exit confirmation toast if enabled in the preferences', (WidgetTester tester) async {
     await Prefs.confirmExitingWithBackButton.set(true);
-    final ToastObserver toastObserver = ToastObserver(tester);
-    final AppObserver appObserver = AppObserver(tester);
     await tester.runAppTest(() async {
-      expect(
-        await appObserver.haveCloseRequest(
-          () => toastObserver.expectShowsToast(
-            BackButtonInterceptor.popRoute,
-            message: l10n.pressOnceAgainToExit,
-            reason: 'Expected the app to ask for confirmation before exiting',
-          ),
-        ),
-        isFalse,
-        reason: 'Expected the app not to close after showing the toast',
-      );
-      await tester.binding.delayed(const Duration(seconds: 5));
-      expect(
-        await appObserver.haveCloseRequest(
-          () => toastObserver.expectShowsToast(
-            BackButtonInterceptor.popRoute,
-            message: l10n.pressOnceAgainToExit,
-            reason: 'Expected the app to ask for confirmation before exiting after the previous message timed out',
-          ),
-        ),
-        isFalse,
-        reason: 'Expected the app not to close after showing the toast',
-      );
-      expect(
-        await appObserver.haveCloseRequest(
-          () => toastObserver.expectShowsNoToast(
-            BackButtonInterceptor.popRoute,
+      final SystemChannelObserver systemObserver = SystemChannelObserver(tester);
+      final ToastChannelObserver toastObserver = ToastChannelObserver(tester);
+      await BackButtonInterceptor.popRoute();
+      expect(toastObserver.lastToastMessage, l10n.pressOnceAgainToExit,
+          reason: 'Expected the app to ask for confirmation before exiting');
+      expect(systemObserver.closeRequests, 0,
+          reason: 'Expected the app not to close after showing the toast');
+      await tester.binding.delayed(Config.BACK_PRESS_CLOSE_TIMEOUT + const Duration(milliseconds: 1));
+      await BackButtonInterceptor.popRoute();
+      expect(toastObserver.lastToastMessage, l10n.pressOnceAgainToExit,
+        reason: 'Expected the app to ask for confirmation before exiting after the previous message timed out');
+      expect(systemObserver.closeRequests, 0,
+        reason: 'Expected the app not to close after showing the toast');
+      await tester.binding.delayed(Config.BACK_PRESS_CLOSE_TIMEOUT - const Duration(milliseconds: 1));
+      await BackButtonInterceptor.popRoute();
+      expect(toastObserver.lastToastMessage, null,
             reason: 'Expected the app to show no toast when pressing the back button a second time',
-          ),
-        ),
-        isTrue,
-      );
+          );
+      expect(systemObserver.closeRequests, 1,
+          reason: 'Expected the app to close if back is pressed after the confirmation toast was shown');
     });
   });
 
-  testWidgets('app respects the exit confirmation preference', (WidgetTester tester) async {
-    await Prefs.confirmExitingWithBackButton.set(true);
-    final ToastObserver toastObserver = ToastObserver(tester);
-    final AppObserver appObserver = AppObserver(tester);
+  testWidgets('app does not ask for exit confirmation if disabled in the preferences', (WidgetTester tester) async {
+    await Prefs.confirmExitingWithBackButton.set(false);
     await tester.runAppTest(() async {
-      expect(
-        await appObserver.haveCloseRequest(
-          () => toastObserver.expectShowsToast(
-            BackButtonInterceptor.popRoute,
-            message: l10n.pressOnceAgainToExit,
-            reason: 'Expected the app to ask for confirmation before exiting',
-          ),
-        ),
-        isFalse,
-        reason: 'Expected the app not to close after showing the toast',
-      );
-      await Prefs.confirmExitingWithBackButton.set(false);
-      await tester.binding.delayed(const Duration(seconds: 5));
-      expect(
-        await appObserver.haveCloseRequest(
-          () => toastObserver.expectShowsNoToast(
-            BackButtonInterceptor.popRoute,
-            reason: 'Expected the app to show no toast when pressing the back button after disabling it',
-          ),
-        ),
-        isTrue,
-        reason: 'Expected the confirmation toast to be disabled',
-      );
+      final SystemChannelObserver systemObserver = SystemChannelObserver(tester);
+      final ToastChannelObserver toastObserver = ToastChannelObserver(tester);
+      await BackButtonInterceptor.popRoute();
+      expect(toastObserver.lastToastMessage, null,
+        reason: 'Expected the app to show no toast when pressing the back button after disabling it');
+      expect(systemObserver.closeRequests, 1,
+        reason: 'Expected the app to close if the confirmation toast is disabled');
     });
   });
 }