Extend HolidayBase::categories to accept a single value (#1550)

docs/source/examples.rst

@@ -148,12 +148,31 @@ To get a list of other categories holidays (for countries that support them):
 
 .. code-block:: python
 
-   >>> for dt, name in sorted(holidays.BE(years=2023, language="en_US", categories=(BANK,)).items()):
+   >>> for dt, name in sorted(holidays.BE(years=2023, language="en_US", categories=BANK).items()):
    >>>     print(dt, name)
    2023-04-07 Good Friday
    2023-05-19 Friday after Ascension Day
    2023-12-26 Bank Holiday
 
+   >>> for dt, name in sorted(holidays.BE(years=2023, language="en_US", categories=(BANK, PUBLIC)).items()):
+   >>>     print(dt, name)
+   2023-01-01 New Year's Day
+   2023-04-07 Good Friday
+   2023-04-09 Easter
+   2023-04-10 Easter Monday
+   2023-05-01 Labor Day
+   2023-05-18 Ascension Day
+   2023-05-19 Friday after Ascension Day
+   2023-05-28 Whit Sunday
+   2023-05-29 Whit Monday
+   2023-07-21 National Day
+   2023-08-15 Assumption of Mary
+   2023-11-01 All Saints' Day
+   2023-11-11 Armistice Day
+   2023-12-25 Christmas Day
+   2023-12-26 Bank Holiday
+
+
 Date from holiday name
 ----------------------
 

holidays/helpers.py

@@ -10,9 +10,31 @@
 #  License: MIT (see LICENSE file)
 
 
+def _normalize_arguments(cls, value):
+    """Normalize arguments.
+
+    :param cls:
+        A type of arguments to normalize.
+
+    :param value:
+        Either a single item or an iterable of `cls` type.
+
+    :return:
+        A set created from `value` argument.
+
+    """
+    if isinstance(value, cls):
+        return {value}
+
+    return set(value) if value is not None else set()
+
+
 def _normalize_tuple(data):
     """Normalize tuple.
 
+    :param data:
+        Either a tuple or a tuple of tuples.
+
     :return:
         An unchanged object for tuple of tuples, e.g., ((JAN, 10), (DEC, 31)).
         An object put into a tuple otherwise, e.g., ((JAN, 10),).

holidays/holiday_base.py

@@ -35,15 +35,17 @@
     _get_nth_weekday_of_month,
 )
 from holidays.constants import HOLIDAY_NAME_DELIMITER, ALL_CATEGORIES, PUBLIC
-from holidays.helpers import _normalize_tuple
+from holidays.helpers import _normalize_arguments, _normalize_tuple
 
+CategoryArg = Union[str, Iterable[str]]
 DateArg = Union[date, Tuple[int, int]]
 DateLike = Union[date, datetime, str, float, int]
 SpecialHoliday = Union[Tuple[int, int, str], Tuple[Tuple[int, int, str], ...]]
 SubstitutedHoliday = Union[
     Union[Tuple[int, int, int, int], Tuple[int, int, int, int, int]],
     Tuple[Union[Tuple[int, int, int, int], Tuple[int, int, int, int, int]], ...],
 ]
+YearArg = Union[int, Iterable[int]]
 
 
 class HolidayBase(Dict[date, str]):
@@ -236,14 +238,14 @@ def _populate(self, year):
 
     def __init__(
         self,
-        years: Optional[Union[int, Iterable[int]]] = None,
+        years: Optional[YearArg] = None,
         expand: bool = True,
         observed: bool = True,
         subdiv: Optional[str] = None,
         prov: Optional[str] = None,  # Deprecated.
         state: Optional[str] = None,  # Deprecated.
         language: Optional[str] = None,
-        categories: Optional[Tuple[str]] = None,
+        categories: Optional[CategoryArg] = None,
     ) -> None:
         """
         :param years:
@@ -282,11 +284,11 @@ def __init__(
         """
         super().__init__()
 
+        self.categories = _normalize_arguments(str, categories or {PUBLIC})
         self.expand = expand
         self.language = language.lower() if language else None
         self.observed = observed
         self.subdiv = subdiv or prov or state
-        self.categories = set(categories) if categories else {PUBLIC}
 
         self.tr = gettext  # Default translation method.
 
@@ -317,7 +319,9 @@ def __init__(
                     DeprecationWarning,
                 )
 
-            unknown_categories = self.categories.difference(ALL_CATEGORIES)
+            unknown_categories = self.categories.difference(  # type: ignore[union-attr]
+                ALL_CATEGORIES
+            )
             if len(unknown_categories) > 0:
                 raise NotImplementedError(
                     f"Category is not supported: {', '.join(unknown_categories)}."
@@ -333,11 +337,7 @@ def __init__(
                 )
                 self.tr = translator.gettext
 
-        if isinstance(years, int):
-            self.years = {years}
-        else:
-            self.years = set(years) if years is not None else set()
-
+        self.years = _normalize_arguments(int, years)
         for year in self.years:
             self._populate(year)
 

tests/countries/test_austria.py

@@ -145,7 +145,7 @@ def test_2022(self):
 
     def test_bank_2022(self):
         self.assertHolidays(
-            Austria(categories=(BANK,), years=2022),
+            Austria(categories=BANK, years=2022),
             ("2022-04-15", "Karfreitag"),
             ("2022-12-24", "Heiliger Abend"),
             ("2022-12-31", "Silvester"),

tests/countries/test_belgium.py

@@ -72,7 +72,7 @@ def test_2022(self):
 
     def test_bank_2022(self):
         self.assertHolidays(
-            Belgium(categories=(BANK,), years=2022),
+            Belgium(categories=BANK, years=2022),
             ("2022-04-15", "Goede Vrijdag"),
             ("2022-05-27", "Vrijdag na O. L. H. Hemelvaart"),
             ("2022-12-26", "Banksluitingsdag"),

tests/countries/test_brazil.py

@@ -90,7 +90,7 @@ def test_christmas_day(self):
         self.assertNoHolidayName("Natal", range(1890, 1922))
 
     def test_optional_holidays(self):
-        holidays = Brazil(categories=(OPTIONAL,))
+        holidays = Brazil(categories=OPTIONAL)
         dt = (
             "2018-02-12",
             "2018-02-13",

tests/countries/test_bulgaria.py

@@ -150,7 +150,7 @@ def test_national_awakening_day(self):
         name = "Ден на народните будители"
         self.assertHolidayName(
             name,
-            Bulgaria(categories=(SCHOOL,), years=range(1990, 2050)),
+            Bulgaria(categories=SCHOOL, years=range(1990, 2050)),
             (f"{year}-11-01" for year in range(1990, 2050)),
         )
         self.assertNoHolidayName(name)