fix: Issue with is_subclass_of for types that are not compatible wi…

…th `issubclass`. (#9)

* feat: Add is_subclass_of method.

* Update type_lens/type_view.py

---------

Co-authored-by: Peter Schutt <[email protected]>

tests/test_type_view.py

@@ -259,7 +259,14 @@ def test_parsed_type_is_optional_predicate() -> None:
 
 
 def test_parsed_type_is_subtype_of() -> None:
-    """Test ParsedType.is_type_of."""
+    """Test TypeView.is_subtype_of."""
+
+    class Foo:
+        pass
+
+    class Bar(Foo):
+        pass
+
     assert TypeView(bool).is_subtype_of(int) is True
     assert TypeView(bool).is_subtype_of(str) is False
     assert TypeView(Union[int, str]).is_subtype_of(int) is False
@@ -268,6 +275,31 @@ def test_parsed_type_is_subtype_of() -> None:
     assert TypeView(Optional[int]).is_subtype_of(int) is False
     assert TypeView(Union[bool, int]).is_subtype_of(int) is True
 
+    assert TypeView(Foo).is_subtype_of(Foo) is True
+    assert TypeView(Bar).is_subtype_of(Foo) is True
+
+
+def test_is_subclass_of() -> None:
+    class Foo:
+        pass
+
+    class Bar(Foo):
+        pass
+
+    assert TypeView(bool).is_subclass_of(int) is True
+    assert TypeView(bool).is_subclass_of(str) is False
+    assert TypeView(Union[int, str]).is_subclass_of(int) is False
+    assert TypeView(List[int]).is_subclass_of(int) is False
+    assert TypeView(Optional[int]).is_subclass_of(int) is False
+    assert TypeView(None).is_subclass_of(int) is False
+    assert TypeView(Literal[1]).is_subclass_of(int) is False
+    assert TypeView(Union[bool, int]).is_subclass_of(int) is False
+
+    assert TypeView(bool).is_subclass_of(bool) is True
+    assert TypeView(List[int]).is_subclass_of(list) is True
+    assert TypeView(Foo).is_subclass_of(Foo) is True
+    assert TypeView(Bar).is_subclass_of(Foo) is True
+
 
 def test_parsed_type_has_inner_subtype_of() -> None:
     """Test ParsedType.has_type_of."""

type_lens/type_view.py

@@ -226,6 +226,17 @@ def is_subtype_of(self, typ: Any | tuple[Any, ...], /) -> bool:
             return issubclass(str, typ) or issubclass(bytes, typ)
         return self.annotation is not Any and not self.is_type_var and issubclass(self.annotation, typ)
 
+    def is_subclass_of(self, typ: Any | tuple[Any, ...], /) -> bool:
+        """Whether the annotation is a subclass of the given type.
+
+        Args:
+            typ: The type to check, or tuple of types. Passed as 2nd argument to ``issubclass()``.
+
+        Returns:
+            Whether the annotation is a subclass of the given type(s).
+        """
+        return isinstance(self.fallback_origin, type) and issubclass(self.fallback_origin, typ)
+
     def strip_optional(self) -> TypeView:
         if not self.is_optional:
             return self