Fix consecutive usage of shortcut & undo

Author: amantoux

packages/fleather/lib/src/widgets/autoformats.dart

@@ -540,7 +540,7 @@ class EmojiShortcuts extends AutoFormat {
     if (!candidate.endsWith(shortcut)) return null;
     final emoji = _emojiShortcut[shortcut]!;
     final change = Delta()
-      ..retain(documentPosition - candidate.length)
+      ..retain(documentPosition - shortcut.length)
       ..delete(shortcut.length)
       ..insert(emoji);
 
@@ -551,8 +551,7 @@ class EmojiShortcuts extends AutoFormat {
         selection: TextSelection.collapsed(
             offset: documentPosition - shortcut.length + emoji.length),
         undo: undo,
-        undoPositionCandidate:
-            documentPosition - shortcut.length + emoji.length,
+        undoPositionCandidate: documentPosition - emoji.length,
         undoSelection: TextSelection.collapsed(offset: documentPosition),
         undoReplacementTest: (length, data) =>
             data is String && data.isEmpty && length == emoji.length);

packages/fleather/test/widgets/controller_test.dart

@@ -486,12 +486,24 @@ void main() {
           const TextSelection.collapsed(offset: '😊'.length));
     });
 
+    test('Consecutive emoji shortcuts', () {
+      controller.replaceText(0, 0, ':');
+      controller.replaceText(1, 0, ')',
+          selection: TextSelection.collapsed(offset: 1));
+      controller.replaceText(2, 0, ':');
+      controller.replaceText(3, 0, ')',
+          selection: TextSelection.collapsed(offset: 3));
+      expect(controller.document.toDelta(), Delta()..insert('😊😊\n'));
+      expect(controller.selection,
+          const TextSelection.collapsed(offset: '😊😊'.length));
+    });
+
     test('Undo emoji shortcuts', () {
       controller.replaceText(0, 0, ':');
       controller.replaceText(1, 0, ')',
           selection: TextSelection.collapsed(offset: 1));
-      controller.replaceText('😊'.length, '😊'.length, '',
-          selection: const TextSelection.collapsed(offset: '😊'.length));
+      controller.replaceText(0, '😊'.length, '',
+          selection: const TextSelection.collapsed(offset: 0));
       expect(controller.document.toDelta(), Delta()..insert(':)\n'));
       expect(controller.selection, const TextSelection.collapsed(offset: 2));
     });