Date Picker jumps back to initialDatePickerMode after day selection (#67926)

Date Picker jumps back to initialDatePickerMode after day selection.

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

@@ -163,6 +163,7 @@ class _CalendarDatePickerState extends State<CalendarDatePicker> {
   @override
   void initState() {
     super.initState();
+    _mode = widget.initialCalendarMode;
     _initWidgetState();
   }
 
@@ -190,7 +191,6 @@ class _CalendarDatePickerState extends State<CalendarDatePicker> {
   }
 
   void _initWidgetState() {
-    _mode = widget.initialCalendarMode;
     _currentDisplayedMonthDate = DateTime(widget.initialDate.year, widget.initialDate.month);
     _selectedDate = widget.initialDate;
   }

packages/flutter/test/material/date_picker_test.dart

@@ -645,6 +645,21 @@ void main() {
         );
       });
     });
+
+    testWidgets('Selecting date does not switch picker to year selection', (WidgetTester tester) async {
+      initialDate = DateTime(2020, DateTime.may, 10);
+      initialCalendarMode = DatePickerMode.year;
+      await prepareDatePicker(tester, (Future<DateTime> date) async {
+        await tester.pump();
+        await tester.tap(find.text('2017'));
+        await tester.pump();
+        expect(find.text('May 2017'), findsOneWidget);
+        await tester.tap(find.text('10'));
+        await tester.pump();
+        expect(find.text('May 2017'), findsOneWidget);
+        expect(find.text('2017'), findsNothing);
+      });
+    });
   });
 
   group('Input mode', () {