Revert "Prevent WhitelistingTextInputFormatter to return a empty string if the...

Revert "Prevent WhitelistingTextInputFormatter to return a empty string if the current value does not satisfy the formatter (#57264)" (#59221)

packages/flutter/lib/src/services/text_formatter.dart

@@ -109,11 +109,10 @@ class BlacklistingTextInputFormatter extends TextInputFormatter {
 
   @override
   TextEditingValue formatEditUpdate(
-    TextEditingValue oldValue,
+    TextEditingValue oldValue, // unused.
     TextEditingValue newValue,
   ) {
     return _selectionAwareTextManipulation(
-      oldValue,
       newValue,
       (String substring) {
         return substring.replaceAll(blacklistedPattern, replacementString);
@@ -242,11 +241,10 @@ class WhitelistingTextInputFormatter extends TextInputFormatter {
 
   @override
   TextEditingValue formatEditUpdate(
-    TextEditingValue oldValue,
+    TextEditingValue oldValue, // unused.
     TextEditingValue newValue,
   ) {
     return _selectionAwareTextManipulation(
-      oldValue,
       newValue,
       (String substring) {
         return whitelistedPattern
@@ -263,7 +261,6 @@ class WhitelistingTextInputFormatter extends TextInputFormatter {
 }
 
 TextEditingValue _selectionAwareTextManipulation(
-  TextEditingValue oldValue,
   TextEditingValue value,
   String substringManipulation(String substring),
 ) {
@@ -273,19 +270,6 @@ TextEditingValue _selectionAwareTextManipulation(
   TextSelection manipulatedSelection;
   if (selectionStartIndex < 0 || selectionEndIndex < 0) {
     manipulatedText = substringManipulation(value.text);
-  } else if (value.selection.isCollapsed) { // Non-selection text manipulation
-    int cursorPosition = value.selection.baseOffset;
-    manipulatedText = substringManipulation(value.text);
-    // We only return the old valid value if the current value is not empty and
-    // if manipulation fails.
-    if (value.text.isNotEmpty && manipulatedText.isEmpty) {
-      manipulatedText = oldValue.text;
-      // We decrease cursorPosition by one because
-      // user entered a invalid character.
-      cursorPosition -= 1;
-    }
-    // Move the caret to its previous position.
-    manipulatedSelection = TextSelection.collapsed(offset: cursorPosition);
   } else {
     final String beforeSelection = substringManipulation(
       value.text.substring(0, selectionStartIndex)

packages/flutter/test/services/text_formatter_test.dart

@@ -86,55 +86,4 @@ void main() {
       });
     });
   });
-
-  group('WhitelistingTextInputFormatter', () {
-    test('should return the old value if new value contains non-white-listed character', () {
-      const TextEditingValue oldValue = TextEditingValue(text: '12345');
-      const TextEditingValue newValue = TextEditingValue(text: '12345@');
-
-      final WhitelistingTextInputFormatter formatter = WhitelistingTextInputFormatter.digitsOnly;
-      final TextEditingValue formatted = formatter.formatEditUpdate(oldValue, newValue);
-
-      // assert that we are passing digits only at the first time
-      expect(oldValue.text, equals('12345'));
-      // The new value is always the oldValue plus a non-digit character (user press @)
-      expect(newValue.text, equals('12345@'));
-      // we expect that the formatted value returns the oldValue only since the newValue does not
-      // satisfy the formatter condition (which is, in this case digitsOnly)
-      expect(formatted.text, equals('12345'));
-    });
-
-    test('should move the cursor to the right position', () {
-      TextEditingValue collapsedValue(String text, int offset) =>
-          TextEditingValue(
-            text: text,
-            selection: TextSelection.collapsed(offset: offset),
-          );
-
-      TextEditingValue oldValue = collapsedValue('123', 0);
-      TextEditingValue newValue = collapsedValue('123456', 6);
-
-      final WhitelistingTextInputFormatter formatter =
-          WhitelistingTextInputFormatter.digitsOnly;
-      TextEditingValue formatted = formatter.formatEditUpdate(oldValue,
-          newValue);
-
-      // assert that we are passing digits only at the first time
-      expect(oldValue.text, equals('123'));
-      // assert that we are passing digits only at the second time
-      expect(newValue.text, equals('123456'));
-      // assert that cursor is at the end of the text
-      expect(formatted.selection.baseOffset, equals(6));
-
-      // move cursor at the middle of the text and then add the number 9.
-      oldValue = newValue.copyWith(
-          selection: const TextSelection.collapsed(offset: 4));
-      newValue = oldValue.copyWith(text: '1239456');
-
-      formatted = formatter.formatEditUpdate(oldValue, newValue);
-
-      // cursor must be now at fourth position (right after the number 9)
-      expect(formatted.selection.baseOffset, equals(4));
-    });
-  });
 }