feat: add isValid to path and fields

app_navigator/lib/src/content_navigator.dart

@@ -1,3 +1,4 @@
+import 'package:flutter/foundation.dart';
 import 'package:tekartik_app_navigator_flutter/content_navigator.dart';
 import 'package:tekartik_app_navigator_flutter/route_aware.dart' as route_aware;
 import 'package:tekartik_app_navigator_flutter/src/route_aware.dart';
@@ -377,6 +378,11 @@ extension ContentNavigatorBlocExt on ContentNavigatorBloc {
   /// Push a path.
   Future<T?> pushPath<T>(ContentPath path,
       {Object? arguments, TransitionDelegate? transitionDelegate}) {
+    if (kDebugMode) {
+      if (!path.isValid()) {
+        throw ArgumentError('Invalid path', path.toString());
+      }
+    }
     return push<T>(path.routeSettings(arguments),
         transitionDelegate: transitionDelegate);
   }

app_navigator/lib/src/content_path.dart

@@ -55,6 +55,16 @@ extension ContentPathExt on ContentPath {
   /// Helper to match a string path directly
   @Deprecated('Use toPathString instead')
   String toPath() => toPathString();
+
+  /// Check if the path is valid and can be pushed
+  bool isValid() {
+    for (var field in fields) {
+      if (!field.isValid()) {
+        return false;
+      }
+    }
+    return true;
+  }
 }
 
 /// A field in a content path.

app_navigator/lib/src/content_path_field.dart

@@ -24,7 +24,9 @@ class ContentPathField {
 
   /// Create a field with a name and an optional value
   ContentPathField(this.name, [String? value])
-      : _value = value == _wildcard ? null : value;
+      : _value = value == _wildcard ? null : value {
+    assert(name.isNotEmpty, 'name cannot be empty');
+  }
 
   @override
   int get hashCode => super.hashCode + (value?.hashCode ?? 0);
@@ -75,6 +77,11 @@ class ContentPathField {
       return '$name/$value';
     }
   }
+
+  /// Check if the field is valid
+  bool isValid() {
+    return value != null && value != _wildcard;
+  }
 }
 
 /// content path list extension

app_navigator/lib/src/content_path_part.dart

@@ -4,4 +4,8 @@ import 'package:tekartik_app_navigator_flutter/content_navigator.dart';
 class ContentPathPart extends ContentPathField {
   /// Create a part with a name (and no value)
   ContentPathPart(String name) : super(name, '');
+
+  /// Always valid
+  @override
+  bool isValid() => true;
 }

app_navigator/test/field_test.dart

@@ -51,5 +51,13 @@ void main() {
       expect(field.value, 'my_value');
       expect(field.name, 'my_name');
     });
+    test('isValid', () {
+      var field = ContentPathField('my_name');
+      expect(field.isValid(), isFalse);
+      field.value = 'my_value';
+      expect(field.isValid(), isTrue);
+      var part = ContentPathPart('my_name');
+      expect(part.isValid(), isTrue);
+    });
   });
 }

app_navigator/test/path_test.dart

@@ -197,6 +197,10 @@ void main() {
       expect(rootContentPath.matchesString('a'), isFalse);
       expect(rootContentPath.matchesString('/a'), isFalse);
     });
+    test('isValid', () {
+      expect(SubPath().isValid(), isFalse);
+      expect((SubPath()..base.value = '123').isValid(), isTrue);
+    });
   });
 }