done

lib/python3.11/site-packages/pandas/tests/tseries/frequencies/test_frequencies.py

@@ -0,0 +1,29 @@
+import pytest
+
+from pandas._libs.tslibs import offsets
+
+from pandas.tseries.frequencies import (
+    is_subperiod,
+    is_superperiod,
+)
+
+
+@pytest.mark.parametrize(
+    "p1,p2,expected",
+    [
+        # Input validation.
+        (offsets.MonthEnd(), None, False),
+        (offsets.YearEnd(), None, False),
+        (None, offsets.YearEnd(), False),
+        (None, offsets.MonthEnd(), False),
+        (None, None, False),
+        (offsets.YearEnd(), offsets.MonthEnd(), True),
+        (offsets.Hour(), offsets.Minute(), True),
+        (offsets.Second(), offsets.Milli(), True),
+        (offsets.Milli(), offsets.Micro(), True),
+        (offsets.Micro(), offsets.Nano(), True),
+    ],
+)
+def test_super_sub_symmetry(p1, p2, expected):
+    assert is_superperiod(p1, p2) is expected
+    assert is_subperiod(p2, p1) is expected