TF-148 Add data layer for cleanup email cache

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);
+    });
+  });
+}