TF-148 Add data layer for cleanup email cache

core/lib/domain/extensions/datetime_extension.dart

@@ -15,6 +15,12 @@ extension DateTimeExtension on DateTime {
     final now = DateTime.now();
     return now.year == this.year;
   }
+
+  int daysBetween(DateTime from) {
+    from = DateTime(from.year, from.month, from.day);
+    final to = DateTime(year, month, day);
+    return (to.difference(from).inHours / 24).round().abs();
+  }
 }
 
 extension DateTimeNullableExtension on DateTime? {

core/pubspec.yaml

@@ -72,6 +72,8 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
+
+  test: 1.16.8
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec
 

core/test/datetime_test.dart

@@ -0,0 +1,29 @@
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:core/core.dart';
+
+void main() {
+  group('datetime test', () {
+
+    test('daysBetween should return 1 day2 when day2 > day1', () async {
+      DateTime date1 = DateTime.parse("2021-10-20 12:59:12.000");
+      DateTime date2 = DateTime.parse("2021-10-21 10:29:03.000");
+
+      expect(date2.daysBetween(date1), 1);
+    });
+
+    test('daysBetween should return 1 days when day1 > day2', () async {
+      DateTime date1 = DateTime.parse("2021-10-22 12:59:12.000");
+      DateTime date2 = DateTime.parse("2021-10-21 10:29:03.000");
+
+      expect(date2.daysBetween(date1), 1);
+    });
+
+    test('daysBetween should return 0 day when day1 = day2', () async {
+      DateTime date1 = DateTime.parse("2021-10-22 12:59:12.000");
+      DateTime date2 = DateTime.parse("2021-10-22 10:29:03.000");
+
+      expect(date2.daysBetween(date1), 0);
+    });
+  });
+}