Input handling improvements for get_nth_working_day (#2770)

Author: PPsyrius

holidays/holiday_base.py

@@ -1116,6 +1116,7 @@ def get_nth_working_day(self, key: DateLike, n: int) -> date:
         """Find the n-th working day from a given date.
 
         Moves forward if n is positive, or backward if n is negative.
+        If n is 0, returns the given date if it is a working day; otherwise the next working day.
 
         Args:
             key:
@@ -1128,10 +1129,11 @@ def get_nth_working_day(self, key: DateLike, n: int) -> date:
         Returns:
             The calculated working day after shifting by n working days.
         """
-        direction = +1 if n > 0 else -1
+        direction = +1 if n >= 0 else -1
         dt = self.__keytransform__(key)
-        for _ in range(abs(n)):
-            dt = _timedelta(dt, direction)
+        for _ in range(abs(n) or 1):
+            if n:
+                dt = _timedelta(dt, direction)
             while not self.is_working_day(dt):
                 dt = _timedelta(dt, direction)
         return dt

tests/test_holiday_base.py

@@ -1262,6 +1262,10 @@ def test_get_nth_working_day(self):
         self.assertEqual(self.hb.get_nth_working_day("2024-05-10", -7), date(2024, 4, 29))
         self.assertEqual(self.hb.get_nth_working_day("2024-05-10", -5), date(2024, 5, 3))
 
+        self.assertEqual(self.hb.get_nth_working_day("2024-07-27", 0), date(2024, 7, 29))
+        self.assertEqual(self.hb.get_nth_working_day("2024-07-27", 1), date(2024, 7, 29))
+        self.assertEqual(self.hb.get_nth_working_day("2024-07-29", 0), date(2024, 7, 29))
+
     def test_get_working_days_count(self):
         self.assertEqual(self.hb.get_working_days_count("2024-01-03", "2024-01-23"), 15)
         self.assertEqual(self.hb.get_working_days_count("2024-01-23", "2024-01-03"), 15)