fix message input quoted message

packages/stream_chat_flutter_core/lib/src/message_input_controller.dart

@@ -40,7 +40,10 @@ class MessageInputController extends ValueNotifier<Message> {
   MessageInputController._({
     required Message initialMessage,
   })  : _textEditingController =
-            TextEditingController(text: initialMessage.text),
+            TextEditingController.fromValue(TextEditingValue(
+          text: initialMessage.text ?? '',
+          composing: TextRange.collapsed(initialMessage.text?.length ?? 0),
+        )),
         _initialMessage = initialMessage,
         super(initialMessage) {
     addListener(_textEditingSyncer);
@@ -83,6 +86,22 @@ class MessageInputController extends ValueNotifier<Message> {
     value = message;
   }
 
+  /// Sets the message that's being quoted.
+  set quotedMessage(Message message) {
+    value = value.copyWith(
+      quotedMessage: message,
+      quotedMessageId: message.id,
+    );
+  }
+
+  /// Clears the quoted message.
+  void clearQuotedMessage() {
+    value = value.copyWith(
+      quotedMessageId: null,
+      quotedMessage: null,
+    );
+  }
+
   /// Sets a command for the message.
   set command(Command command) {
     value = value.copyWith(

packages/stream_chat_flutter_core/test/message_input_controller_test.dart

@@ -3,28 +3,12 @@ import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
 void main() {
   testWidgets(
-    'should instantiate a new MessageInputController with default validator'
-    ' and empty message',
+    'should instantiate a new MessageInputController with empty message',
     (tester) async {
-      final controller = MessageInputController();
+      final controller = MessageInputController()..text = 'test';
 
-      expect(controller.isValid, false);
-      controller.text = 'test';
-      expect(controller.isValid, true);
-    },
-  );
-
-  testWidgets(
-    'should instantiate a new MessageInputController with default validator'
-    ' and specified message',
-    (tester) async {
-      final message = Message(text: 'test');
-      final controller = MessageInputController(
-        message: message,
-      );
-
-      expect(controller.message, message);
-      expect(controller.isValid, true);
+      expect(controller.text, 'test');
+      expect(controller.message.text, 'test');
     },
   );
 }