Find all converter subclasses / descendants

src/undate/converters/base.py

@@ -114,7 +114,7 @@ def available_converters(cls) -> Dict[str, Type["BaseDateConverter"]]:
         return {c.name: c for c in cls.subclasses()}  # type: ignore
 
     @classmethod
-    def subclasses(cls) -> list[Type["BaseDateConverter"]]:
+    def subclasses(cls) -> set[Type["BaseDateConverter"]]:
         """
         List of available converters classes. Includes calendar convert
         subclasses.
@@ -123,11 +123,16 @@ def subclasses(cls) -> list[Type["BaseDateConverter"]]:
         cls.import_converters()
 
         # find all direct subclasses, excluding base calendar converter
-        subclasses = cls.__subclasses__()
-        subclasses.remove(BaseCalendarConverter)
-        # add all subclasses of calendar converter base class
-        subclasses.extend(BaseCalendarConverter.__subclasses__())
-        return subclasses
+        direct_subclasses = cls.__subclasses__()
+        all_subclasses = set(direct_subclasses)
+        # recurse to find nested subclasses
+        for subc in direct_subclasses:
+            # print(f"class subclasses: {subc.name} {subc.subclasses()}")
+            all_subclasses |= subc.subclasses()
+
+        # omit the calendar converter base class, which is not itself a converter
+        all_subclasses -= {BaseCalendarConverter}
+        return all_subclasses
 
 
 class BaseCalendarConverter(BaseDateConverter):

tests/test_converters/test_base.py

@@ -2,6 +2,11 @@
 
 import pytest
 from undate.converters.base import BaseDateConverter, BaseCalendarConverter
+from undate.converters.calendars import (
+    GregorianDateConverter,
+    HebrewDateConverter,
+    HijriDateConverter,
+)
 
 
 class TestBaseDateConverter:
@@ -29,6 +34,18 @@ def test_parse_to_string(self):
         with pytest.raises(NotImplementedError):
             BaseDateConverter().to_string(1991)
 
+    def test_subclasses(self):
+        # define a nested subclass
+        class SubSubConverter(HijriDateConverter):
+            pass
+
+        subclasses = BaseDateConverter.subclasses()
+        assert BaseCalendarConverter not in subclasses
+        assert HijriDateConverter in subclasses
+        assert HebrewDateConverter in subclasses
+        assert GregorianDateConverter in subclasses
+        assert SubSubConverter in subclasses
+
 
 def test_import_converters_import_only_once(caplog):
     # clear the cache, since any instantiation of an Undate