Handle validation errors for callable objects and builtins

Author: xiehuanyi

src/validators/utils.py

@@ -2,8 +2,7 @@
 
 # standard
 from functools import wraps
-from inspect import getfullargspec
-from itertools import chain
+from inspect import signature
 from os import environ
 from typing import Any, Callable, Dict
 
@@ -20,8 +19,9 @@ def __init__(self, function: Callable[..., Any], arg_dict: Dict[str, Any], messa
 
     def __repr__(self):
         """Repr Validation Failure."""
+        func_name = getattr(self.func, "__name__", type(self.func).__name__)
         return (
-            f"ValidationError(func={self.func.__name__}, "
+            f"ValidationError(func={func_name}, "
             + f"args={ ({k: v for (k, v) in self.__dict__.items() if k != 'func'}) })"
         )
 
@@ -36,10 +36,12 @@ def __bool__(self):
 
 def _func_args_as_dict(func: Callable[..., Any], *args: Any, **kwargs: Any):
     """Return function's positional and key value arguments as an ordered dictionary."""
-    return dict(
-        list(zip(dict.fromkeys(chain(getfullargspec(func)[0], kwargs.keys())), args))
-        + list(kwargs.items())
-    )
+    try:
+        return dict(signature(func).bind_partial(*args, **kwargs).arguments)
+    except (TypeError, ValueError):
+        # Some builtins have no inspectable signature. Retain the raw call
+        # instead of letting error reporting raise another exception.
+        return {"positional_args": args, "keyword_args": kwargs}
 
 
 def validator(func: Callable[..., Any]):

tests/test_validation_failure.py

@@ -1,13 +1,14 @@
 """Test validation Failure."""
 
 # standard
+from functools import partial
 from typing import Any, Callable
 
 # third-party
 import pytest
 
 # local
-from validators import ValidationError, between, slug, uuid
+from validators import ValidationError, between, slug, uuid, validator
 
 
 @pytest.mark.parametrize("function,value", [(slug, "invalid_"), (uuid, "not-a-uuid")])
@@ -69,3 +70,72 @@ def test_arguments_as_properties(self):
         assert self.is_in_between.__dict__["value"] == 3
         assert self.is_in_between.__dict__["min_val"] == 4
         assert self.is_in_between.__dict__["max_val"] == 5
+
+
+def test_partial_validation_error_representation():
+    """Validation errors support partial callables without a name attribute."""
+
+    def above(value: int, minimum: int) -> bool:
+        return value > minimum
+
+    check = validator(partial(above, minimum=3))
+    error = check(1)
+    assert isinstance(error, ValidationError)
+    assert repr(error) == "ValidationError(func=partial, args={'value': 1})"
+    assert str(error) == repr(error)
+    assert check(4) is True
+
+
+def test_callable_instance_validation_error_representation():
+    """Callable instance errors use their type name."""
+
+    class Positive:
+        def __call__(self, *, value: int) -> bool:
+            return value > 0
+
+    error = validator(Positive())(value=-1)
+    assert isinstance(error, ValidationError)
+    assert repr(error) == "ValidationError(func=Positive, args={'value': -1})"
+
+
+def test_builtin_validation_error_keeps_raw_arguments():
+    """An unavailable builtin signature must not hide its validation error."""
+    check = validator(int)
+    error = check("invalid")
+    assert isinstance(error, ValidationError)
+    assert "func=int" in repr(error)
+    assert error.__dict__["positional_args"] == ("invalid",)
+    assert error.__dict__["keyword_args"] == {}
+    assert "invalid literal" in error.reason
+    assert check("42") is True
+
+    with pytest.raises(ValidationError, match="func=int"):
+        check("invalid", r_ve=True)
+
+
+def test_callable_instance_positional_validation_error_arguments():
+    """Positional callable instance arguments exclude the bound instance."""
+
+    class Positive:
+        def __call__(self, value: int) -> bool:
+            return value > 0
+
+    error = validator(Positive())(-1)
+    assert isinstance(error, ValidationError)
+    assert error.__dict__["value"] == -1
+    assert "self" not in error.__dict__
+    assert repr(error) == "ValidationError(func=Positive, args={'value': -1})"
+
+
+def test_bound_method_positional_validation_error_arguments():
+    """Positional bound method arguments exclude the bound instance."""
+
+    class Positive:
+        def check(self, value: int) -> bool:
+            return value > 0
+
+    error = validator(Positive().check)(-1)
+    assert isinstance(error, ValidationError)
+    assert error.__dict__["value"] == -1
+    assert "self" not in error.__dict__
+    assert repr(error) == "ValidationError(func=check, args={'value': -1})"