Add tests for range slider updates

Author: velten-dev

test/form_builder_range_slider_test.dart

@@ -27,6 +27,7 @@ void main() {
           tester.getBottomRight(find.byType(RangeSlider)).translate(-24, 0);
       final Offset rightTarget = topLeft + (bottomRight - topLeft) * 0.5;
       await tester.tapAt(rightTarget);
+      await tester.pumpAndSettle();
 
       expect(formSave(), isTrue);
       expect(formValue<RangeValues>(widgetName), const RangeValues(10.0, 15.0));
@@ -54,9 +55,66 @@ void main() {
           tester.getBottomRight(find.byType(RangeSlider)).translate(-24, 0);
       final Offset leftTarget = topLeft + (bottomRight - topLeft) * 0.1;
       await tester.tapAt(leftTarget);
+      await tester.pumpAndSettle();
 
       expect(formSave(), isTrue);
       expect(formValue<RangeValues>(widgetName), const RangeValues(11.0, 18.0));
     });
+
+    testWidgets('Stateful Update', (WidgetTester tester) async {
+      const widgetName = 'formBuilderRangeSlider';
+      const testWidget = _FormBuilderRangeSliderStateTest(widgetName);
+      await tester.pumpWidget(buildTestableFieldWidget(testWidget));
+
+      expect(formSave(), isTrue);
+      expect(
+        formValue<RangeValues?>(widgetName),
+        equals(const RangeValues(-10.0, 10.0)),
+      );
+
+      await tester.tapAt(tester.getCenter(find.byType(TextButton)));
+      await tester.pumpAndSettle();
+
+      expect(formSave(), isTrue);
+      expect(
+        formValue<RangeValues?>(widgetName),
+        equals(const RangeValues(-9.0, 9.0)),
+      );
+    });
   });
 }
+
+class _FormBuilderRangeSliderStateTest extends StatefulWidget {
+  final String name;
+
+  const _FormBuilderRangeSliderStateTest(this.name);
+
+  @override
+  State<StatefulWidget> createState() =>
+      _FormBuilderRangeSliderStateTestState();
+}
+
+class _FormBuilderRangeSliderStateTestState
+    extends State<_FormBuilderRangeSliderStateTest> {
+  double range = 10;
+
+  @override
+  Widget build(BuildContext context) {
+    return Row(
+      children: [
+        Expanded(
+          child: FormBuilderRangeSlider(
+            name: widget.name,
+            min: -range,
+            max: range,
+            initialValue: RangeValues(-range, range),
+          ),
+        ),
+        TextButton(
+          onPressed: () => setState(() => range -= 1),
+          child: const Text('Reduce Range'),
+        )
+      ],
+    );
+  }
+}