Refactor Background widget constructors to use private constructor for improved encapsulation

oui/lib/src/app/oui_app.dart

@@ -47,7 +47,7 @@ class OuiApp extends StatelessWidget {
     this.config = const OuiConfig(),
   }) : _registry = OuiScreenRegistry(root, null) {
     _routerInformationParser = OuiRouteInformationParser(_registry);
-    _router = OuiRouter(_registry);
+    _router = OuiRouter();
   }
 
   @override

oui/lib/src/router/oui_path.dart

@@ -188,8 +188,6 @@ class OuiPath {
   /// Returns a new [OuiPath] with the given [segments] appended to the end.
   /// If [segments] is empty, returns this path.
   OuiPath add(List<OuiPathSegment> segments) {
-    assert(
-        segments.every((s) => s != null), 'Cannot add null segments to path');
     if (segments.isEmpty) {
       return this;
     }

oui/lib/src/router/oui_router.dart

@@ -2,15 +2,12 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 import 'oui_path_match.dart';
 import '../scaffold/oui_scaffold.dart';
-import '../screens/oui_screen_registry.dart';
 
 class OuiRouter extends RouterDelegate<OuiPathMatch> with ChangeNotifier {
-  final OuiScreenRegistry _registry;
-
   OuiPathMatch _activeMatch = OuiPathMatch.noMatch;
   OuiPathMatch get match => _activeMatch;
 
-  OuiRouter(this._registry);
+  OuiRouter();
 
   @override
   OuiPathMatch? get currentConfiguration => _activeMatch;

oui/lib/src/utils/background.dart

@@ -5,24 +5,23 @@ class Background extends StatelessWidget {
   final Gradient? gradient;
   final Widget Function(BuildContext)? custom;
 
-  const Background({
-    super.key,
+  const Background._({
     this.color,
     this.gradient,
     this.custom,
   });
 
-  factory Background.color(Color color) => Background(color: color);
+  factory Background.color(Color color) => Background._(color: color);
 
   factory Background.gradient(Gradient gradient) =>
-      Background(gradient: gradient);
+      Background._(gradient: gradient);
 
   factory Background.custom(
     Widget Function(BuildContext) custom, {
     Color? color,
     Gradient? gradient,
   }) =>
-      Background(
+      Background._(
         color: color,
         gradient: gradient,
         custom: custom,
@@ -37,20 +36,25 @@ class Background extends StatelessWidget {
         decoration: BoxDecoration(gradient: gradient),
       );
     } else if (color != null) {
-      background = Container(color: color);
+      background = Container(
+        decoration: BoxDecoration(color: color),
+      );
     }
 
-    if (custom != null && background != null) {
-      background = Stack(
-        children: [
-          background,
-          custom!(context),
-        ],
-      );
-    } else {
-      background = custom!(context);
+    if (custom != null) {
+      if (background != null) {
+        background = Stack(
+          children: [
+            background,
+            custom!(context),
+          ],
+        );
+      } else {
+        background = custom!(context);
+      }
     }
 
-    return background;
+    // Fallback to an empty widget if all parameters are null
+    return background ?? const SizedBox.shrink();
   }
 }

oui/test/background_test.dart

@@ -0,0 +1,97 @@
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:oui/src/utils/background.dart';
+
+void main() {
+  testWidgets('Background with color', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      WidgetsApp(
+        color: const Color(0xFFFFFFFF),
+        builder: (context, _) => Background.color(const Color(0xFFFF0000)),
+      ),
+    );
+
+    final container = tester.widget<Container>(find.byType(Container));
+    expect(
+      (container.decoration as BoxDecoration?)?.color,
+      const Color(0xFFFF0000),
+    );
+    expect(find.byType(Container), findsOneWidget);
+  });
+
+  testWidgets('Background with gradient', (WidgetTester tester) async {
+    const gradient = LinearGradient(
+      colors: [Color(0xFFFF0000), Color(0xFF0000FF)],
+      begin: Alignment.centerLeft,
+      end: Alignment.centerRight,
+    );
+
+    await tester.pumpWidget(
+      WidgetsApp(
+        color: const Color(0xFFFFFFFF),
+        builder: (context, _) => Background.gradient(gradient),
+      ),
+    );
+
+    final container = tester.widget<Container>(find.byType(Container));
+    final boxDecoration = container.decoration as BoxDecoration?;
+    expect(boxDecoration?.gradient, gradient);
+  });
+
+  testWidgets('Background with custom widget', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      WidgetsApp(
+        color: const Color(0xFFFFFFFF),
+        builder: (context, _) => Background.custom(
+          (context) => const Text('Custom Widget'),
+        ),
+      ),
+    );
+
+    expect(find.text('Custom Widget'), findsOneWidget);
+  });
+
+  testWidgets('Background with color and custom widget',
+      (WidgetTester tester) async {
+    await tester.pumpWidget(
+      WidgetsApp(
+        color: const Color(0xFFFFFFFF),
+        builder: (context, _) => Background.custom(
+          (context) => const Text('Custom Widget'),
+          color: const Color(0xFFFF0000),
+        ),
+      ),
+    );
+
+    final container = tester.widget<Container>(find.byType(Container));
+    expect(
+      (container.decoration as BoxDecoration?)?.color,
+      const Color(0xFFFF0000),
+    );
+    expect(find.text('Custom Widget'), findsOneWidget);
+  });
+
+  testWidgets('Background with gradient and custom widget',
+      (WidgetTester tester) async {
+    const gradient = LinearGradient(
+      colors: [Color(0xFFFF0000), Color(0xFF0000FF)],
+      begin: Alignment.centerLeft,
+      end: Alignment.centerRight,
+    );
+
+    await tester.pumpWidget(
+      WidgetsApp(
+        color: const Color(0xFFFFFFFF),
+        builder: (context, _) => Background.custom(
+          (context) => const Text('Custom Widget'),
+          gradient: gradient,
+        ),
+      ),
+    );
+
+    final container = tester.widget<Container>(find.byType(Container));
+    final boxDecoration = container.decoration as BoxDecoration?;
+    expect(boxDecoration?.gradient, gradient);
+    expect(find.text('Custom Widget'), findsOneWidget);
+  });
+}