Fix: Issue with single character formatting in the toggle style button .

lib/src/toolbar/buttons/toggle_style_button.dart

@@ -135,15 +135,8 @@ class QuillToolbarToggleStyleButtonState
   }
 
   bool _getIsToggled(Map<String, Attribute> attrs) {
-    if (widget.attribute.key == Attribute.list.key ||
-        widget.attribute.key == Attribute.header.key ||
-        widget.attribute.key == Attribute.script.key ||
-        widget.attribute.key == Attribute.align.key) {
-      final attribute = attrs[widget.attribute.key];
-      if (attribute == null) {
-        return false;
-      }
-      return attribute.value == widget.attribute.value;
+    if (controller.selection.end - controller.selection.start == 1) {
+      return false;
     }
     return attrs.containsKey(widget.attribute.key);
   }

test/common/utils/quill_test_app.dart

@@ -35,61 +35,38 @@ class QuillTestApp extends StatelessWidget {
   ///
   /// Either [home] or [scaffoldBody] must be provided.
   /// Throws an [ArgumentError] if both are provided.
-  QuillTestApp({
-    required this.home,
-    required this.scaffoldBody,
-    this.onLocalizationsAvailable,
+  const QuillTestApp({
+    required this.child,
     super.key,
-  }) {
-    if (home != null && scaffoldBody != null) {
-      throw ArgumentError('Either the home or scaffoldBody must be null');
-    }
-  }
+  });
 
   /// Creates a [QuillTestApp] with a [Scaffold] wrapping the given [body] widget.
-  factory QuillTestApp.withScaffold(Widget body,
-          {LocalizationsAvailableCallback? onLocalizationsAvailable}) =>
-      QuillTestApp(
-        home: null,
-        scaffoldBody: body,
-        onLocalizationsAvailable: onLocalizationsAvailable,
-      );
+static Widget withScaffold(Widget child) {
+  return MaterialApp(
+    localizationsDelegates: FlutterQuillLocalizations.localizationsDelegates,
+    supportedLocales: FlutterQuillLocalizations.supportedLocales,
+    home: Scaffold(
+      body: child,
+    ),
+  );
+}
 
   /// Creates a [QuillTestApp] with the specified [home] widget.
   factory QuillTestApp.home(Widget home,
           {LocalizationsAvailableCallback? onLocalizationsAvailable}) =>
       QuillTestApp(
-        home: home,
-        scaffoldBody: null,
-        onLocalizationsAvailable: onLocalizationsAvailable,
+        child: home,
       );
 
   /// The home widget for the application.
-  ///
-  /// If [home] is not null, [scaffoldBody] must be null.
-  final Widget? home;
-
-  /// The body widget for a [Scaffold] used as the application home.
-  ///
-  /// If [scaffoldBody] is not null, [home] must be null.
-  final Widget? scaffoldBody;
-
-  final LocalizationsAvailableCallback? onLocalizationsAvailable;
+  final Widget child;
 
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       localizationsDelegates: FlutterQuillLocalizations.localizationsDelegates,
       supportedLocales: FlutterQuillLocalizations.supportedLocales,
-      home: Builder(builder: (context) {
-        if (onLocalizationsAvailable != null) {
-          onLocalizationsAvailable?.call(context.loc);
-        }
-        return home ??
-            Scaffold(
-              body: scaffoldBody,
-            );
-      }),
+      home: child,
     );
   }
 }

test/toolbar/buttons/toggle_style_button_test.dart

@@ -0,0 +1,72 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_quill/flutter_quill.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../../common/utils/quill_test_app.dart';
+
+void main() {
+  group('QuillToolbarToggleStyleButton', () {
+    testWidgets('should not toggle toolbar state when formatting single character',
+        (tester) async {
+      final controller = QuillController.basic();
+      controller.document.insert(0, 'Hello World');
+
+      await tester.pumpWidget(
+        QuillTestApp.withScaffold(
+          QuillToolbarToggleStyleButton(
+            controller: controller,
+            attribute: Attribute.bold,
+          ),
+        ),
+      );
+
+      // Format a single character
+      controller.formatText(0, 1, Attribute.bold);
+
+      // Verify the toolbar button is not toggled
+      final button = tester.widget<QuillToolbarIconButton>(
+        find.byType(QuillToolbarIconButton),
+      );
+      expect(button.isSelected, false);
+
+      // Format multiple characters
+      controller.formatText(0, 5, Attribute.bold);
+
+      // Verify the toolbar button is now toggled
+      await tester.pump();
+      final buttonAfterMultiFormat = tester.widget<QuillToolbarIconButton>(
+        find.byType(QuillToolbarIconButton),
+      );
+      expect(buttonAfterMultiFormat.isSelected, true);
+    });
+
+    testWidgets('should maintain formatting for single character',
+        (tester) async {
+      final controller = QuillController.basic();
+      controller.document.insert(0, 'Hello World');
+
+      await tester.pumpWidget(
+        QuillTestApp.withScaffold(
+          QuillToolbarToggleStyleButton(
+            controller: controller,
+            attribute: Attribute.bold,
+          ),
+        ),
+      );
+
+      // Format a single character
+      controller.formatText(0, 1, Attribute.bold);
+
+      // Verify the character is bold
+      final style = controller.document.collectStyle(0, 1);
+      expect(style.attributes.containsKey(Attribute.bold.key), true);
+
+      // Type new text after the bold character
+      controller.replaceText(1, 0, 'New text', null);
+
+      // Verify the new text is not bold
+      final newStyle = controller.document.collectStyle(1, 9);
+      expect(newStyle.attributes.containsKey(Attribute.bold.key), false);
+    });
+  });
+}