test: improve aslist test

tests/test_as_list.py

@@ -1,38 +1,31 @@
-from dataclasses import is_dataclass
-from typing import Generic, List, TypeVar
+from functools import lru_cache
+from typing import TYPE_CHECKING, Generic, List, TypeVar, Union
 
 import pydantic
 import pytest
-from pydantic import BaseModel
-from typing_extensions import is_typeddict
 
 from confit import validate_arguments
 from confit.errors import ConfitValidationError, patch_errors
 
 T = TypeVar("T")
-if pydantic.VERSION < "2":
 
-    def cast(type_, obj):
-        class Model(pydantic.BaseModel):
-            __root__: type_
-
-            class Config:
-                arbitrary_types_allowed = True
-
-        return Model(__root__=obj).__root__
-
-else:
-    from pydantic.type_adapter import ConfigDict, TypeAdapter
+if pydantic.VERSION >= "2":
     from pydantic_core import core_schema
 
-    def make_type_adapter(type_):
-        config = None
-        if not issubclass(type, BaseModel) or is_dataclass(type) or is_typeddict(type):
-            config = ConfigDict(arbitrary_types_allowed=True)
-        return TypeAdapter(type_, config=config)
 
-    def cast(type_, obj):
-        return make_type_adapter(type_).validate_python(obj)
+class Validated:
+    @classmethod
+    def __get_validators__(cls):
+        yield cls.validate
+
+    @classmethod
+    def __get_pydantic_core_schema__(cls, source, handler):
+        return core_schema.chain_schema(
+            [
+                core_schema.no_info_plain_validator_function(v)
+                for v in cls.__get_validators__()
+            ]
+        )
 
 
 class MetaAsList(type):
@@ -68,6 +61,44 @@ class AsList(Generic[T], metaclass=MetaAsList):
     pass
 
 
+if pydantic.VERSION < "2":
+
+    def cast(type_, obj):
+        class Model(pydantic.BaseModel):
+            __root__: type_
+
+            class Config:
+                arbitrary_types_allowed = True
+
+        return Model(__root__=obj).__root__
+
+else:
+    from dataclasses import is_dataclass
+
+    from pydantic import BaseModel
+    from pydantic.type_adapter import ConfigDict, TypeAdapter
+    from typing_extensions import is_typeddict
+
+    @lru_cache(maxsize=32)
+    def make_type_adapter(type_):
+        config = None
+
+        if not (
+            (isinstance(type_, type) and issubclass(type_, BaseModel))
+            or is_dataclass(type_)
+            or is_typeddict(type_)
+        ):
+            config = ConfigDict(arbitrary_types_allowed=True)
+        return TypeAdapter(type_, config=config)
+
+    def cast(type_, obj):
+        return make_type_adapter(type_).validate_python(obj)
+
+
+if TYPE_CHECKING:
+    AsList = Union[T, List[T]]  # noqa: F811
+
+
 def test_as_list():
     @validate_arguments
     def func(a: AsList[int]):