Day picker should dispose created MaterialStatesController's. (#133884)

Fixes https://github.com/flutter/flutter/issues/133862

packages/flutter/lib/src/material/calendar_date_picker.dart

@@ -868,6 +868,10 @@ class _DayPickerState extends State<_DayPicker> {
   /// List of [FocusNode]s, one for each day of the month.
   late List<FocusNode> _dayFocusNodes;
 
+  // TODO(polina-c): a cleaner solution is to create separate statefull widget for a day.
+  // https://github.com/flutter/flutter/issues/134323
+  final Map<int, MaterialStatesController> _statesControllers = <int, MaterialStatesController>{};
+
   @override
   void initState() {
     super.initState();
@@ -893,6 +897,9 @@ class _DayPickerState extends State<_DayPicker> {
     for (final FocusNode node in _dayFocusNodes) {
       node.dispose();
     }
+    for (final MaterialStatesController controller in _statesControllers.values) {
+      controller.dispose();
+    }
     super.dispose();
   }
 
@@ -973,6 +980,9 @@ class _DayPickerState extends State<_DayPicker> {
           if (isSelectedDay) MaterialState.selected,
         };
 
+        final MaterialStatesController statesController = _statesControllers.putIfAbsent(day, () => MaterialStatesController());
+        statesController.value = states;
+
         final Color? dayForegroundColor = resolve<Color?>((DatePickerThemeData? theme) => isToday ? theme?.todayForegroundColor : theme?.dayForegroundColor, states);
         final Color? dayBackgroundColor = resolve<Color?>((DatePickerThemeData? theme) => isToday ? theme?.todayBackgroundColor : theme?.dayBackgroundColor, states);
         final MaterialStateProperty<Color?> dayOverlayColor = MaterialStateProperty.resolveWith<Color?>(
@@ -1008,7 +1018,7 @@ class _DayPickerState extends State<_DayPicker> {
             focusNode: _dayFocusNodes[day - 1],
             onTap: () => widget.onChanged(dayToBuild),
             radius: _dayPickerRowHeight / 2 + 4,
-            statesController: MaterialStatesController(states),
+            statesController: statesController,
             overlayColor: dayOverlayColor,
             child: Semantics(
               // We want the day of month to be spoken first irrespective of the

packages/flutter/test/material/calendar_date_picker_test.dart

@@ -516,6 +516,30 @@ void main() {
       expect(find.text('2017'), findsNothing);
     });
 
+    testWidgets('Selecting disabled date does not change current selection', (WidgetTester tester) async {
+      DateTime day(int day) => DateTime(2020, DateTime.may, day);
+
+      DateTime selection = day(2);
+      await tester.pumpWidget(calendarDatePicker(
+        initialDate: selection,
+        firstDate: day(2),
+        lastDate: day(3),
+        onDateChanged: (DateTime date) {
+          selection = date;
+        },
+      ));
+
+      await tester.tap(find.text('3'));
+      await tester.pumpAndSettle();
+      expect(selection, day(3));
+      await tester.tap(find.text('4'));
+      await tester.pumpAndSettle();
+      expect(selection, day(3));
+      await tester.tap(find.text('5'));
+      await tester.pumpAndSettle();
+      expect(selection, day(3));
+    });
+
     for (final bool useMaterial3 in <bool>[false, true]) {
       testWidgets('Updates to initialDate parameter are not reflected in the state (useMaterial3=$useMaterial3)', (WidgetTester tester) async {
         final Key pickerKey = UniqueKey();

packages/flutter/test/material/date_picker_test.dart

@@ -8,7 +8,6 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
@@ -173,16 +172,11 @@ void main() {
       }, useMaterial3: theme.useMaterial3);
     });
 
-    testWidgetsWithLeakTracking('Material3 uses sentence case labels', (WidgetTester tester) async {
+    testWidgets('Material3 uses sentence case labels', (WidgetTester tester) async {
       await prepareDatePicker(tester, (Future<DateTime?> date) async {
         expect(find.text('Select date'), findsOneWidget);
       }, useMaterial3: true);
-    },
-    leakTrackingTestConfig: const LeakTrackingTestConfig(
-      // TODO(polina-c): remove after fixing
-      // https://github.com/flutter/flutter/issues/133862
-      allowAllNotDisposed: true,
-    ));
+    });
 
     testWidgets('Cancel, confirm, and help text is used', (WidgetTester tester) async {
       cancelText = 'nope';