Use dedicated birthday entry controls (#67)

frontend/app/test/kyc_test.dart

@@ -11,6 +11,7 @@ import 'package:sxchnge_analytics/sxchnge_analytics.dart';
 
 import 'package:sxchnge_kyc/sxchnge_kyc.dart';
 
+import 'package:sxchnge_app/kyc/birth.dart';
 import 'package:sxchnge_app/kyc/country.dart';
 import 'package:sxchnge_app/main.dart';
 import 'package:sxchnge_app/providers/locale.dart';
@@ -66,10 +67,16 @@ void main() {
     return service;
   }
 
-  Future<void> submit(WidgetTester t) async {
+  Future<void> profile(WidgetTester t) async {
     await tap(t, find.byKey(const ValueKey('kyc-start')));
     await t.enterText(find.byKey(const ValueKey('kyc-name')), 'Example Person');
-    await t.enterText(find.byKey(const ValueKey('kyc-birth')), '1990-04-23');
+    await t.enterText(find.byKey(const ValueKey('birth-day')), '23');
+    await tap(t, find.byType(DropdownButtonFormField<int>));
+    // The month label follows the selected app locale.
+    await tap(t, find.textContaining(RegExp(r'^(April|апрель)$')).last);
+    await t.enterText(find.byKey(const ValueKey('birth-year')), '1990');
+    await t.pumpAndSettle();
+    expect(t.widget<BirthField>(find.byType(BirthField)).value, '1990-04-23');
     await tap(
       t,
       find.descendant(
@@ -85,6 +92,10 @@ void main() {
       'PL',
     );
     await t.pumpAndSettle();
+  }
+
+  Future<void> submit(WidgetTester t) async {
+    await profile(t);
     await tap(t, find.byKey(const ValueKey('pick-passport')));
     await tap(t, find.byKey(const ValueKey('kyc-next')));
     await tap(t, find.byKey(const ValueKey('pick-selfie')));
@@ -93,6 +104,41 @@ void main() {
     await tap(t, find.byKey(const ValueKey('kyc-submit')));
   }
 
+  testWidgets(
+    'invalid birthday blocks advancing and valid birthday survives Back',
+    (t) async {
+      await open(t);
+      await profile(t);
+      await tap(t, find.byKey(const ValueKey('pick-passport')));
+      final next = find.byKey(const ValueKey('kyc-next'));
+      await t.enterText(find.byKey(const ValueKey('birth-day')), '31');
+      await t.pumpAndSettle();
+      expect(t.widget<FilledButton>(next).onPressed, isNull);
+      expect(find.text('Enter a valid date of birth.'), findsOneWidget);
+      await t.enterText(find.byKey(const ValueKey('birth-day')), '23');
+      await t.pumpAndSettle();
+      expect(t.widget<FilledButton>(next).onPressed, isNotNull);
+      await tap(t, next);
+      await tap(t, find.text('Back'));
+      expect(t.widget<BirthField>(find.byType(BirthField)).value, '1990-04-23');
+      expect(
+        t
+            .widget<TextFormField>(find.byKey(const ValueKey('birth-day')))
+            .controller!
+            .text,
+        '23',
+      );
+      expect(find.text('April'), findsOneWidget);
+      expect(
+        t
+            .widget<TextFormField>(find.byKey(const ValueKey('birth-year')))
+            .controller!
+            .text,
+        '1990',
+      );
+    },
+  );
+
   testWidgets('two photos, review, pending and approval with service limits', (
     t,
   ) async {