Add inherited dataclass annotation validation (#1)

Author: trissim

docs/source/conf.py

@@ -16,7 +16,7 @@
 project = "python-introspect"
 copyright = "2025, Tristan Simas"
 author = "Tristan Simas"
-release = "0.1.6"
+release = "0.1.7"
 version = "0.1"
 
 # -- General configuration ---------------------------------------------------

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "python-introspect"
-version = "0.1.6"
+version = "0.1.7"
 description = "Pure Python introspection toolkit for function signatures, dataclasses, and type hints"
 readme = "README.md"
 requires-python = ">=3.10"

src/python_introspect/__init__.py

@@ -9,7 +9,7 @@
     type resolution for framework-specific types (lazy configs, proxies, etc.)
 """
 
-__version__ = "0.1.6"
+__version__ = "0.1.7"
 
 from .signature_analyzer import (
     SignatureAnalyzer,
@@ -41,6 +41,7 @@
     mark_enableable,
 )
 from .validation import (
+    AnnotatedDataclassValidationMixin,
     AnnotationValidationError,
     overlay_non_none_dataclass,
     validate_annotated_dataclass,
@@ -95,6 +96,7 @@
     "is_enableable",
     "mark_enableable",
     # Runtime annotation validation
+    "AnnotatedDataclassValidationMixin",
     "AnnotationValidationError",
     "overlay_non_none_dataclass",
     "validate_annotated_dataclass",

src/python_introspect/validation.py

@@ -27,6 +27,19 @@ class AnnotationValidationError(ValueError):
 DataclassT = TypeVar("DataclassT")
 
 
+class AnnotatedDataclassValidationMixin:
+    """Validate a dataclass instance from its resolved annotations after construction.
+
+    Dataclass declarations inherit this mixin when their annotations are the
+    authoritative runtime schema. Keeping the lifecycle hook on a nominal base
+    also preserves validation when another package recreates the dataclass with
+    the same bases.
+    """
+
+    def __post_init__(self) -> None:
+        validate_annotated_dataclass(self)
+
+
 def overlay_non_none_dataclass(
     base: DataclassT,
     overlay: object,

tests/test_init.py

@@ -11,7 +11,7 @@ def test_version_available(self):
         """Test that __version__ is available."""
         assert hasattr(python_introspect, "__version__")
         assert isinstance(python_introspect.__version__, str)
-        assert python_introspect.__version__ == "0.1.6"
+        assert python_introspect.__version__ == "0.1.7"
 
     def test_signature_analyzer_import(self):
         """Test SignatureAnalyzer is importable."""

tests/test_validation.py

@@ -1,11 +1,12 @@
-from dataclasses import dataclass
+from dataclasses import dataclass, make_dataclass
 from enum import Enum
 from typing import Annotated, Literal
 
 import pytest
 from annotated_types import Ge, Gt, Le, MinLen, Predicate
 
 from python_introspect import (
+    AnnotatedDataclassValidationMixin,
     overlay_non_none_dataclass,
     validate_annotated_dataclass,
 )
@@ -21,13 +22,10 @@ class Mode(Enum):
 
 
 @dataclass(frozen=True)
-class BaseConfig:
+class BaseConfig(AnnotatedDataclassValidationMixin):
     port: Port = 7000
     mode: Mode = Mode.FIRST
 
-    def __post_init__(self) -> None:
-        validate_annotated_dataclass(self)
-
 
 @dataclass(frozen=True)
 class ChildConfig(BaseConfig):
@@ -53,6 +51,19 @@ def test_validation_rejects_wrong_nominal_types_without_coercion() -> None:
         ChildConfig(mode="first")
 
 
+def test_inherited_validation_survives_dataclass_recreation() -> None:
+    RecreatedConfig = make_dataclass(
+        "RecreatedConfig",
+        (("port", Port, 7000),),
+        bases=(AnnotatedDataclassValidationMixin,),
+        frozen=True,
+    )
+
+    assert RecreatedConfig(port=8000).port == 8000
+    with pytest.raises(ValueError, match="port must be at least"):
+        RecreatedConfig(port=0)
+
+
 @dataclass(frozen=True)
 class OptionalConfig:
     port: Port | None = None