feat: support updating character of character shortcut event

lib/src/editor/editor_component/service/shortcuts/character_shortcut_event.dart

@@ -19,14 +19,35 @@ class CharacterShortcutEvent {
   /// Usually, uses the description as the key.
   final String key;
 
+  /// The character to trigger the shortcut event.
+  ///
+  /// It mus tbe a single character.
   String character;
 
+  //// The handler to handle the shortcut event.
   final CharacterShortcutEventHandler handler;
 
+  void updateCharacter(String newCharacter) {
+    assert(newCharacter.length == 1);
+    character = newCharacter;
+  }
+
   Future<bool> execute(EditorState editorState) async {
     return handler(editorState);
   }
 
+  CharacterShortcutEvent copyWith({
+    String? key,
+    String? character,
+    CharacterShortcutEventHandler? handler,
+  }) {
+    return CharacterShortcutEvent(
+      key: key ?? this.key,
+      character: character ?? this.character,
+      handler: handler ?? this.handler,
+    );
+  }
+
   @override
   String toString() =>
       'CharacterShortcutEvent(key: $key, character: $character, handler: $handler)';

test/new/service/shortcuts/character_shortcut_events/character_shortcut_event_test.dart

@@ -0,0 +1,32 @@
+import 'package:appflowy_editor/appflowy_editor.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() async {
+  group('character shortcut event', () {
+    test('update character_shortcut_event\'s character', () async {
+      final event = CharacterShortcutEvent(
+        key: 'test',
+        character: 'a',
+        handler: (editorState) async => true,
+      );
+      expect(event.character, 'a');
+      event.updateCharacter('b');
+      expect(event.character, 'b');
+    });
+
+    test('copy character_shortcut_event', () async {
+      final event = CharacterShortcutEvent(
+        key: 'test',
+        character: 'a',
+        handler: (editorState) async => true,
+      );
+      final newEvent = event.copyWith(
+        character: 'b',
+        handler: (editorState) async => false,
+      );
+      expect(newEvent.character, 'b');
+      expect(await newEvent.execute(EditorState.blank()), false);
+    });
+  });
+}