Add test for gregorian converter to version control

Author: rlskoeser

tests/test_converters/test_calendars/test_gregorian.py

@@ -0,0 +1,35 @@
+from undate.converters.calendars import GregorianDateConverter
+
+
+class TestGregorianDateConverter:
+    def test_to_gregorian(self):
+        converter = GregorianDateConverter()
+        # conversion is a no-op, returns values unchanged
+        assert converter.to_gregorian(2025, 6, 15) == (2025, 6, 15)
+
+    def test_min_month(self):
+        assert GregorianDateConverter().min_month() == 1
+
+    def test_max_month(self):
+        assert GregorianDateConverter().max_month(2025) == 12
+
+    # todo: test max day
+    #
+    def test_representative_years(self):
+        converter = GregorianDateConverter()
+        # single year is not filtered
+        assert converter.representative_years([2025]) == [2025]
+        # multiple non-leap years, returns just the first
+        assert converter.representative_years([2025, 2026]) == [2025]
+        # next leap year is 2028; returns first leap year and first non-leap year, in input order
+        assert converter.representative_years([2025, 2026, 2028, 2029]) == [2025, 2028]
+
+        # if no years are provided, returns a known leap year and non-leap years
+        assert converter.representative_years() == [
+            converter.LEAP_YEAR,
+            converter.NON_LEAP_YEAR,
+        ]
+        assert converter.representative_years([]) == [
+            converter.LEAP_YEAR,
+            converter.NON_LEAP_YEAR,
+        ]