feat: support enum.Enum subtypes

Author: seandstewart

src/typelib/marshals/api.py

@@ -114,6 +114,8 @@ def __call__(self, val: T) -> serdes.MarshalledValueT:
     inspection.isliteral: routines.LiteralMarshaller,
     # Special handler for Unions...
     inspection.isuniontype: routines.UnionMarshaller,
+    # Special handling for Enums
+    inspection.isenumtype: routines.EnumMarshaller,
     # Non-intersecting types (order doesn't matter here.
     inspection.isdatetimetype: routines.DateTimeMarshaller,
     inspection.isdatetype: routines.DateMarshaller,

src/typelib/marshals/routines.py

@@ -6,6 +6,7 @@
 import contextlib
 import datetime
 import decimal
+import enum
 import fractions
 import pathlib
 import re
@@ -41,6 +42,7 @@
     "SubscriptedMappingMarshaller",
     "FixedTupleMarshaller",
     "StructuredTypeMarshaller",
+    "EnumMarshaller",
 )
 
 
@@ -151,6 +153,20 @@ def __call__(self, val: T) -> str:
 PathT = tp.TypeVar("PathT", bound=pathlib.Path)
 PathMarshaller = ToStringMarshaller[PathT]
 
+EnumT = tp.TypeVar("EnumT", bound=enum.Enum)
+
+
+class EnumMarshaller(AbstractMarshaller[EnumT], tp.Generic[EnumT]):
+    """A marshaller that converts an [`enum.Enum`][] instance to its assigned value."""
+
+    def __call__(self, val: EnumT) -> serdes.MarshalledValueT:
+        """Marshal an [`enum.Enum`][] instance into a [`serdes.MarshalledValueT`][].
+
+        Args:
+            val: The enum instance to marshal.
+        """
+        return val.value
+
 
 PatternT = tp.TypeVar("PatternT", bound=re.Pattern)
 

src/typelib/py/inspection.py

@@ -903,7 +903,7 @@ def isenumtype(obj: type) -> compat.TypeIs[type[enum.Enum]]:
         >>> isenumtype(FooNum)
         True
     """
-    return issubclass(obj, enum.Enum)
+    return _safe_issubclass(obj, enum.Enum)
 
 
 @compat.cache

src/typelib/unmarshals/api.py

@@ -108,6 +108,8 @@ def __call__(self, val: tp.Any) -> T:
     inspection.isliteral: routines.LiteralUnmarshaller,
     # Special handler for Unions...
     inspection.isuniontype: routines.UnionUnmarshaller,
+    # Special handling for Enums
+    inspection.isenumtype: routines.EnumUnmarshaller,
     # Non-intersecting types (order doesn't matter here.
     inspection.isdatetimetype: routines.DateTimeUnmarshaller,
     inspection.isdatetype: routines.DateUnmarshaller,

src/typelib/unmarshals/routines.py

@@ -6,6 +6,7 @@
 import contextlib
 import datetime
 import decimal
+import enum
 import fractions
 import numbers
 import pathlib
@@ -46,6 +47,7 @@
     "SubscriptedMappingUnmarshaller",
     "FixedTupleUnmarshaller",
     "StructuredTypeUnmarshaller",
+    "EnumUnmarshaller",
 )
 
 
@@ -537,7 +539,7 @@ def __call__(self, val: tp.Any) -> UUIDT:
 
 
 class PatternUnmarshaller(AbstractUnmarshaller[PatternT], tp.Generic[PatternT]):
-    """Unmarshaller that converts an input to a[`re.Pattern`][].
+    """Unmarshaller that converts an input to a [`re.Pattern`][].
 
     Note:
         You can't instantiate a [`re.Pattern`][] directly, so we don't have a good
@@ -596,6 +598,9 @@ def __call__(self, val: tp.Any) -> T:
 MappingUnmarshaller = CastUnmarshaller[tp.Mapping]
 IterableUnmarshaller = CastUnmarshaller[tp.Iterable]
 
+EnumT = tp.TypeVar("EnumT", bound=enum.Enum)
+EnumUnmarshaller = CastUnmarshaller[EnumT]
+
 
 LiteralT = tp.TypeVar("LiteralT")
 

tests/models.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import dataclasses
+import enum
 import typing
 
 
@@ -49,3 +50,7 @@ class NTuple(typing.NamedTuple):
 class TDict(typing.TypedDict):
     field: str
     value: int
+
+
+class GivenEnum(enum.Enum):
+    one = "one"

tests/unit/marshals/test_api.py

@@ -137,6 +137,11 @@
         ),
         expected_output={"indirect": {"cycle": {"indirect": {"cycle": None}}}},
     ),
+    enum_type=dict(
+        given_type=models.GivenEnum,
+        given_input=models.GivenEnum.one,
+        expected_output=models.GivenEnum.one.value,
+    ),
 )
 def test_marshal(given_type, given_input, expected_output):
     # When

tests/unit/marshals/test_routines.py

@@ -449,3 +449,14 @@ def test_invalid_union():
     # When/Then
     with pytest.raises(expected_exception):
         given_marshaller(given_value)
+
+
+def test_enum_unmarshaller():
+    # Given
+    given_unmarshaller = routines.EnumMarshaller(models.GivenEnum, {})
+    given_value = models.GivenEnum.one
+    expected_value = models.GivenEnum.one.value
+    # When
+    unmarshalled = given_unmarshaller(given_value)
+    # Then
+    assert unmarshalled == expected_value

tests/unit/unmarshal/__init__.py renamed to tests/unit/unmarshals/__init__.py

@@ -137,6 +137,11 @@
         given_input='["1", "2"]',
         expected_output=[1, 2],
     ),
+    enum_type=dict(
+        given_type=models.GivenEnum,
+        given_input="one",
+        expected_output=models.GivenEnum.one,
+    ),
 )
 def test_unmarshal(given_type, given_input, expected_output):
     # When