fix(bull_ui): keep numeric inputs single-line

Author: wired-pasteque

packages/bull_ui/lib/src/inputs/bull_input_text.dart

@@ -143,8 +143,12 @@ class _BullInputTextState extends State<BullInputText> {
   @override
   Widget build(BuildContext context) {
     final colors = context.bull;
+    // Numeric and obscured fields are never legitimately multiline, so they
+    // default to a single line instead of Flutter's unlimited `null`.
+    final effectiveMaxLines =
+        widget.maxLines ?? (widget.obscure || widget.onlyNumbers ? 1 : null);
     final shouldPreventNewlines =
-        widget.maxLines != null && widget.maxLines! <= 2;
+        effectiveMaxLines != null && effectiveMaxLines <= 2;
 
     return TextField(
       key: widget.uiKey,
@@ -171,7 +175,7 @@ class _BullInputTextState extends State<BullInputText> {
       enableIMEPersonalizedLearning: false,
       maxLength: widget.maxLength,
       minLines: widget.minLines ?? 1,
-      maxLines: widget.maxLines ?? (widget.obscure ? 1 : null),
+      maxLines: effectiveMaxLines,
       style:
           widget.style ??
           Theme.of(context).textTheme.headlineSmall?.copyWith(

packages/bull_ui/test/bull_input_text_test.dart

@@ -0,0 +1,76 @@
+import 'package:bull_ui/bull_ui.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'test_app.dart';
+
+void main() {
+  Future<void> pumpInput(
+    WidgetTester tester, {
+    bool onlyNumbers = false,
+    bool obscure = false,
+    int? maxLines,
+  }) async {
+    await tester.pumpWidget(
+      wrapWithTheme(
+        BullInputText(
+          value: '',
+          onlyNumbers: onlyNumbers,
+          obscure: obscure,
+          maxLines: maxLines,
+          onChanged: (_) {},
+        ),
+      ),
+    );
+  }
+
+  TextField findTextField(WidgetTester tester) =>
+      tester.widget<TextField>(find.byType(TextField));
+
+  group('BullInputText line behaviour', () {
+    testWidgets('numeric fields are single-line', (tester) async {
+      await pumpInput(tester, onlyNumbers: true);
+
+      expect(findTextField(tester).maxLines, 1);
+    });
+
+    testWidgets('numeric fields submit instead of inserting a newline', (
+      tester,
+    ) async {
+      await pumpInput(tester, onlyNumbers: true);
+
+      expect(findTextField(tester).textInputAction, TextInputAction.done);
+    });
+
+    testWidgets('numeric fields reject newline characters', (tester) async {
+      await pumpInput(tester, onlyNumbers: true);
+
+      await tester.enterText(find.byType(TextField), '10\n\n20');
+      await tester.pump();
+
+      expect(find.text('1020'), findsOneWidget);
+    });
+
+    testWidgets('obscured fields stay single-line', (tester) async {
+      await pumpInput(tester, obscure: true);
+
+      expect(findTextField(tester).maxLines, 1);
+    });
+
+    testWidgets('free-text fields remain multiline', (tester) async {
+      await pumpInput(tester);
+
+      final textField = findTextField(tester);
+      expect(textField.maxLines, isNull);
+      expect(textField.textInputAction, TextInputAction.newline);
+    });
+
+    testWidgets('an explicit maxLines wins over the numeric default', (
+      tester,
+    ) async {
+      await pumpInput(tester, onlyNumbers: true, maxLines: 3);
+
+      expect(findTextField(tester).maxLines, 3);
+    });
+  });
+}