Replace AlphaVersionBanner with DevelopmentStageBanner. (#1291)

This replaces the `AlphaVersionBanner` with `DevelopmentStageBanner` so
that a banner is always shown if the user uses a non-stable version of
Sharezone.
This is useful for #1290 (new "preview" stage for preview builds in
PRs).

Currently the banner is only shown in alpha, not in beta. This will show
a banner in alpha and beta.


![grafik](https://github.com/SharezoneApp/sharezone-app/assets/29028262/44bcbfa5-8137-4fe2-81f0-a0cc7db2e9d1)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Introduced a Development Stage Banner to inform users about the
current development stage of the app.
- **Refactor**
- Improved the flexibility of testing by allowing the development stage
variable to be overridden.
- Enhanced the Development Stage Banner to dynamically display the app's
development stage.
- **Tests**
- Added tests to ensure the Development Stage Banner accurately reflects
the app's current stage.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

app/lib/main/constants.dart

@@ -6,4 +6,7 @@
 //
 // SPDX-License-Identifier: EUPL-1.2
 
+// Can be overridden for testing purposes.
+String? kDevelopmentStageOrNull =
+    kDevelopmentStage == "" ? null : kDevelopmentStage;
 const kDevelopmentStage = String.fromEnvironment('DEVELOPMENT_STAGE');

app/lib/main/sharezone.dart

@@ -14,25 +14,24 @@ import 'package:bloc_provider/multi_bloc_provider.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:flutter/material.dart';
 import 'package:overlay_support/overlay_support.dart';
+import 'package:platform_check/platform_check.dart';
 import 'package:provider/provider.dart';
 import 'package:sharezone/account/theme/theme_settings.dart';
 import 'package:sharezone/dynamic_links/beitrittsversuch.dart';
 import 'package:sharezone/dynamic_links/dynamic_link_bloc.dart';
 import 'package:sharezone/dynamic_links/dynamic_links.dart';
 import 'package:sharezone/main/auth_app.dart';
 import 'package:sharezone/main/bloc_dependencies.dart';
-import 'package:sharezone/main/constants.dart';
 import 'package:sharezone/main/sharezone_app.dart';
 import 'package:sharezone/main/sharezone_bloc_providers.dart';
 import 'package:sharezone/navigation/logic/navigation_bloc.dart';
 import 'package:sharezone/notifications/notifications_permission.dart';
 import 'package:sharezone/onboarding/group_onboarding/logic/signed_up_bloc.dart';
 import 'package:sharezone/sharezone_plus/subscription_service/subscription_flag.dart';
 import 'package:sharezone/util/flavor.dart';
-import 'package:sharezone/widgets/alpha_version_banner.dart';
 import 'package:sharezone/widgets/animation/color_fade_in.dart';
+import 'package:sharezone/widgets/development_stage_banner.dart';
 import 'package:sharezone_utils/device_information_manager.dart';
-import 'package:platform_check/platform_check.dart';
 import 'package:sharezone_widgets/sharezone_widgets.dart';
 
 /// Defines if the app is running in integration test mode.
@@ -112,8 +111,7 @@ class _SharezoneState extends State<Sharezone> with WidgetsBindingObserver {
             textDirection: TextDirection.ltr,
             child: _ThemeSettingsProvider(
               blocDependencies: widget.blocDependencies,
-              child: AlphaVersionBanner(
-                enabled: kDevelopmentStage == 'ALPHA',
+              child: DevelopmentStageBanner(
                 child: Stack(
                   children: [
                     MultiProvider(

app/lib/widgets/alpha_version_banner.dart → app/lib/widgets/development_stage_banner.dart

@@ -8,49 +8,53 @@
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
+import 'package:sharezone/main/constants.dart';
 
-/// Displays a [Banner] saying "ALPHA" when running an alpha version at top left
-/// hand corner.
+/// Displays the current development stage as a [Banner] if it is not stable.
 ///
-/// Displays nothing when [enabled] is false.
+/// Sharezone has different development stages e.g. "alpha", "beta", "preview".
+/// This widget displays the current development stage as a [Banner] at the top
+/// hand corner of the screen if we are not in the stable/production development
+/// stage.
+///
+/// This is intended so that users know that they are using a non-stable version
+/// of the app and that they should expect bugs and other issues.
 ///
 /// This widget is similar and inspired by the [CheckedModeBanner] which displays
 /// "DEBUG" at the top right hand corner when running a Flutter app in debug
 /// mode.
-class AlphaVersionBanner extends StatelessWidget {
+class DevelopmentStageBanner extends StatelessWidget {
   /// Creates a const alpha version banner.
-  const AlphaVersionBanner({
+  const DevelopmentStageBanner({
     super.key,
     required this.child,
-    required this.enabled,
   });
 
   /// The widget to show behind the banner.
   final Widget child;
 
-  /// Defines if the alpha banner should shown.
-  ///
-  /// If set to false, the banner will not be shown and is not visible.
-  final bool enabled;
+  bool get _isStable =>
+      kDevelopmentStageOrNull == null || _uppercasedStage == 'STABLE';
+  String? get _uppercasedStage => kDevelopmentStageOrNull?.toUpperCase();
 
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
     String message = 'disabled';
-    if (enabled) {
-      message = 'ALPHA';
+    if (!_isStable) {
+      message = _uppercasedStage!;
     }
     properties.add(DiagnosticsNode.message(message));
   }
 
   @override
   Widget build(BuildContext context) {
-    if (!enabled) {
+    if (_isStable) {
       return child;
     }
 
     return Banner(
-      message: 'ALPHA',
+      message: _uppercasedStage!,
       textDirection: TextDirection.ltr,
       location: BannerLocation.topEnd,
       color: Colors.blue,

app/test_goldens/widgets/development_stage_banner_test.dart

@@ -0,0 +1,85 @@
+// Copyright (c) 2022 Sharezone UG (haftungsbeschränkt)
+// Licensed under the EUPL-1.2-or-later.
+//
+// You may obtain a copy of the Licence at:
+// https://joinup.ec.europa.eu/software/page/eupl
+//
+// SPDX-License-Identifier: EUPL-1.2
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:golden_toolkit/golden_toolkit.dart';
+import 'package:sharezone/main/constants.dart';
+import 'package:sharezone/widgets/development_stage_banner.dart';
+
+void main() {
+  group('$DevelopmentStageBanner', () {
+    testGoldens(
+      'displays the banner at the correct position',
+      (tester) async {
+        kDevelopmentStageOrNull = 'alpha';
+
+        await tester.pumpWidgetBuilder(
+          const DevelopmentStageBanner(
+            child: MaterialApp(
+              debugShowCheckedModeBanner: false,
+              home: Scaffold(
+                body: Text("Text"),
+              ),
+            ),
+          ),
+        );
+
+        await screenMatchesGolden(tester, 'alpha_version_banner');
+      },
+    );
+
+    testWidgets("does display the banner if stage is alpha, beta or preview",
+        (tester) async {
+      for (var stage in ['alpha', 'beta', 'preview']) {
+        kDevelopmentStageOrNull = stage;
+
+        await tester.pumpWidget(
+          const Directionality(
+            textDirection: TextDirection.ltr,
+            child: DevelopmentStageBanner(
+              child: MaterialApp(
+                debugShowCheckedModeBanner: false,
+                home: Scaffold(
+                  body: Text("Text"),
+                ),
+              ),
+            ),
+          ),
+        );
+
+        expect(find.byType(Banner), findsOneWidget,
+            reason: 'Stage "$stage" should display the banner');
+      }
+    });
+
+    testWidgets("does not display the banner if stage is 'stable' or null",
+        (tester) async {
+      for (var stage in ['stable', null]) {
+        kDevelopmentStageOrNull = stage;
+
+        await tester.pumpWidget(
+          const Directionality(
+            textDirection: TextDirection.ltr,
+            child: DevelopmentStageBanner(
+              child: MaterialApp(
+                debugShowCheckedModeBanner: false,
+                home: Scaffold(
+                  body: Text("Text"),
+                ),
+              ),
+            ),
+          ),
+        );
+
+        expect(find.byType(Banner), findsNothing,
+            reason: 'Stage "$stage" should not display the banner');
+      }
+    });
+  });
+}