Conditions: an empty text variable is empty; obscure fixed-height password fields

isEmpty on a text variable holding "" was false: the empty text reads as
null and isEmpty(null) returned false, so a form couldn't check that its
error messages were cleared before submitting.

A fixed-height text field expands, which leaves maxLines null, and only
single-line fields were obscured, so a PIN or password field in a fixed
box showed its text. An obscured field that isn't explicitly multi-line
now keeps one line.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011WedhUVWdWR5swqZYMuGfP

Author: claude

lib/src/transformers/node_transformers/passive_text_field_transformer.dart

@@ -310,11 +310,20 @@ class _PassiveTextFieldWidgetState extends State<PassiveTextFieldWidget> {
         !widget.settings.isPreview &&
         (widget.autofocus ?? properties.autoFocus);
 
-    final (int? maxLines, int? minLines) = resolveTextFieldLines(
-      maxLines: properties.maxLines,
-      minLines: properties.minLines,
-      expands: !widget.node.isVerticalWrap,
-    );
+    // Flutter only obscures single-line fields, so an obscured field that
+    // isn't explicitly multi-line (a PIN or password in a fixed-height box)
+    // keeps one line instead of expanding to the box.
+    final bool singleLineObscured =
+        obscureText &&
+        (properties.maxLines ?? 1) <= 1 &&
+        (properties.minLines ?? 1) <= 1;
+    final (int? maxLines, int? minLines) = singleLineObscured
+        ? (1, null)
+        : resolveTextFieldLines(
+            maxLines: properties.maxLines,
+            minLines: properties.minLines,
+            expands: !widget.node.isVerticalWrap,
+          );
 
     Widget field = TextFormField(
       focusNode: focusNode,
@@ -352,7 +361,7 @@ class _PassiveTextFieldWidgetState extends State<PassiveTextFieldWidget> {
       ],
       maxLines: maxLines,
       minLines: minLines,
-      expands: !widget.node.isVerticalWrap,
+      expands: !singleLineObscured && !widget.node.isVerticalWrap,
       obscuringCharacter: widget.node.properties.obscuringCharacter,
       style: TextUtils.retrieveTextStyleFromProp(
         widget.node.properties.inputStyle,

lib/src/transformers/utils/condition_evaluator.dart

@@ -201,6 +201,9 @@ class ConditionEvaluator<R extends Object>
 
   @override
   bool visitIsEmptyOperator(Object? left) {
+    // An empty text variable reads as null (see _visitRawValue), and an unset
+    // one is null too: both are empty.
+    if (left == null) return true;
     if (left is List) return left.isEmpty;
     if (left is String) return left.isEmpty;
     if (left is Map) return left.isEmpty;

test/condition_is_empty_test.dart

@@ -0,0 +1,74 @@
+import 'package:codelessly_api/codelessly_api.dart';
+import 'package:codelessly_sdk/codelessly_sdk.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+/// isEmpty / isNotEmpty on text variables, the way a form validates its
+/// error messages before submitting.
+void main() {
+  bool check(Map<String, Object?> vars, String path, String operator) {
+    final BaseExpression expression = BaseExpression.fromJson({
+      'type': 'Expression',
+      'leftPart': {'type': 'Variable', 'valueString': '\${$path}'},
+      'operator': operator,
+      'rightPart': {'type': 'RawValue', 'value': ''},
+    });
+    return expression.accept<bool>(
+          ConditionEvaluator<Object>(
+            scopedValues: ScopedValues.preview(
+              variables: {
+                for (final MapEntry(:key, :value) in vars.entries)
+                  key: VariableData(id: key, name: key, value: value),
+              },
+            ),
+          ),
+        ) ==
+        true;
+  }
+
+  test('an empty text variable is empty', () {
+    expect(check({'error': ''}, 'error', 'isEmpty'), isTrue);
+    expect(check({'error': ''}, 'error', 'isNotEmpty'), isFalse);
+  });
+
+  test('a text variable with a value is not empty', () {
+    expect(check({'error': 'Incorrect PIN'}, 'error', 'isEmpty'), isFalse);
+    expect(check({'error': 'Incorrect PIN'}, 'error', 'isNotEmpty'), isTrue);
+  });
+
+  test('a missing variable is empty', () {
+    expect(check({}, 'missing', 'isEmpty'), isTrue);
+    expect(check({}, 'missing', 'isNotEmpty'), isFalse);
+  });
+
+  test('both errors empty, joined with and', () {
+    final BaseExpression expression = BaseExpression.fromJson({
+      'type': 'ExpressionGroup',
+      'join': 'and',
+      'leftExpression': {
+        'type': 'Expression',
+        'leftPart': {'type': 'Variable', 'valueString': r'${idError}'},
+        'operator': 'isEmpty',
+        'rightPart': {'type': 'RawValue', 'value': ''},
+      },
+      'rightExpression': {
+        'type': 'Expression',
+        'leftPart': {'type': 'Variable', 'valueString': r'${pinError}'},
+        'operator': 'isEmpty',
+        'rightPart': {'type': 'RawValue', 'value': ''},
+      },
+    });
+    expect(
+      expression.accept<bool>(
+        ConditionEvaluator<Object>(
+          scopedValues: ScopedValues.preview(
+            variables: {
+              'idError': VariableData(id: 'a', name: 'idError', value: ''),
+              'pinError': VariableData(id: 'b', name: 'pinError', value: ''),
+            },
+          ),
+        ),
+      ),
+      isTrue,
+    );
+  });
+}

test/text_field_lines_test.dart

@@ -142,6 +142,28 @@ void main() {
       _expectOnScreen(tester, size);
     });
 
+    testWidgets('fixed-height password field is obscured at $label', (
+      tester,
+    ) async {
+      await _pump(
+        tester,
+        _field(
+          maxLines: 1,
+          minLines: null,
+          verticalFit: SizeFit.fixed,
+          obscureText: true,
+        ),
+        size,
+      );
+      expect(tester.takeException(), isNull);
+      final TextField field = tester.widget(find.byType(TextField));
+      expect(field.obscureText, isTrue);
+      expect(field.expands, isFalse);
+      expect(field.maxLines, 1);
+      expect(tester.getSize(find.byType(TextField)).height, 120);
+      _expectOnScreen(tester, size);
+    });
+
     testWidgets('fixed-height field expands with lines set at $label', (
       tester,
     ) async {