tests: add edge cases

Author: Rodrigo Roldán

tests/test_edge_cases.py

@@ -0,0 +1,33 @@
+from datetime import datetime, timedelta
+from zoneinfo import ZoneInfo
+
+import pytest
+
+from eones.core.date import Date
+from eones.core.delta import Delta
+
+
+def test_leap_year_add_and_subtract():
+    base = Date(datetime(2020, 2, 29, tzinfo=ZoneInfo("UTC")))
+    plus_one = base + Delta(years=1)
+    assert plus_one.to_datetime() == datetime(2021, 2, 28, tzinfo=ZoneInfo("UTC"))
+    minus_one = plus_one - Delta(years=1)
+    assert minus_one.to_datetime() == datetime(2020, 2, 28, tzinfo=ZoneInfo("UTC"))
+    plus_four = base + Delta(years=4)
+    assert plus_four.to_datetime() == datetime(2024, 2, 29, tzinfo=ZoneInfo("UTC"))
+
+
+def test_dst_spring_forward_hour_skipped():
+    zone = "America/New_York"
+    dt = Date(datetime(2023, 3, 12, 1, 30, tzinfo=ZoneInfo(zone)), tz=zone)
+    shifted = dt + timedelta(hours=1)
+    result = shifted.to_datetime()
+    assert result.hour == 2
+    assert result.utcoffset().total_seconds() / 3600 == -5
+
+
+def test_add_then_subtract_symmetry():
+    base = Date(datetime(2024, 5, 15, 10, 0, tzinfo=ZoneInfo("UTC")))
+    delta = Delta(days=3, hours=5)
+    result = (base + delta) - delta
+    assert result == base