Add tests for datetime serialization.

tests/test_storage.py

@@ -0,0 +1,40 @@
+from unittest import TestCase
+from datetime import datetime, timezone
+from eduvpn.storage import serialize_datetime, deserialize_datetime
+
+
+utc = timezone.utc
+
+
+class DateTimeSerializationTests(TestCase):
+    def test_serialize_datetime(self):
+        self.assertEqual(
+            serialize_datetime(datetime(2022, 1, 3, 13, 46, 29, 0, utc)),
+            '2022-01-03T13:46:29+00:00',
+        )
+
+    def test_deserialize_datetime(self):
+        self.assertEqual(
+            deserialize_datetime('2022-01-03T13:46:29'),
+            datetime(2022, 1, 3, 13, 46, 29, 0, utc),
+        )
+        self.assertEqual(
+            deserialize_datetime('2022-01-03T13:46:29.123456'),
+            datetime(2022, 1, 3, 13, 46, 29, 123456, utc),
+        )
+
+        self.assertEqual(
+            deserialize_datetime('2022-01-03T13:46:29+00:00'),
+            datetime(2022, 1, 3, 13, 46, 29, 0, utc),
+        )
+        self.assertEqual(
+            deserialize_datetime('2022-01-03T13:46:29-00:00'),
+            datetime(2022, 1, 3, 13, 46, 29, 0, utc),
+        )
+
+    def test_serialize_roundtrip(self):
+        dt = datetime.now(timezone.utc)
+        self.assertEqual(
+            deserialize_datetime(serialize_datetime(dt)),
+            dt,
+        )