fix: wrap unresolvable $ref in ValidationError

When a $ref points to a nonexistent target, the referencing library's
Unresolvable (PointerToNowhere) exception escaped uncaught instead of being
wrapped in a ValidationError. This leaked the internal library exception
(and, as a side effect, dumped the entire spec into the error message).

Catch Unresolvable in SpecValidator.validate() and is_valid(), wrap in
jsonschema.exceptions.ValidationError. Updated existing test_ref_failed tests
to expect ValidationError (the documented behavior) instead of Unresolvable
(the leak). Fixes #511.

Assisted-by: Claude (Anthropic).
Co-Authored-By: claude-flow <ruv@ruv.net>

Author: patchwright

openapi_spec_validator/validation/validators.py

@@ -7,6 +7,8 @@
 from functools import lru_cache
 from typing import cast
 
+from referencing.exceptions import Unresolvable
+
 from jsonschema.exceptions import ValidationError
 from jsonschema.protocols import Validator
 from jsonschema_path.handlers import default_handlers
@@ -69,11 +71,17 @@ def __init__(
         )
 
     def validate(self) -> None:
-        for err in self.iter_errors():
-            raise err
+        try:
+            for err in self.iter_errors():
+                raise err
+        except Unresolvable as exc:
+            raise ValidationError(str(exc)) from exc
 
     def is_valid(self) -> bool:
-        error = next(self.iter_errors(), None)
+        try:
+            error = next(self.iter_errors(), None)
+        except Unresolvable:
+            return False
         return error is None
 
     @property

tests/integration/validation/test_validators.py

@@ -1,4 +1,5 @@
 import pytest
+from jsonschema.exceptions import ValidationError
 from jsonschema_path import SchemaPath
 from referencing.exceptions import Unresolvable
 
@@ -65,7 +66,7 @@ def test_ref_failed(self, factory, spec_file):
         spec = factory.spec_from_file(spec_path)
         spec_url = factory.spec_file_url(spec_path)
 
-        with pytest.raises(Unresolvable):
+        with pytest.raises(ValidationError):
             OpenAPIV2SpecValidator(spec, base_uri=spec_url).validate()
 
 
@@ -177,7 +178,7 @@ def test_ref_failed(self, factory, spec_file):
         spec = factory.spec_from_file(spec_path)
         spec_url = factory.spec_file_url(spec_path)
 
-        with pytest.raises(Unresolvable):
+        with pytest.raises(ValidationError):
             OpenAPIV30SpecValidator(spec, base_uri=spec_url).validate()