Narrower handling around unresolved refs

Author: p1c2u

openapi_schema_validator/_keywords.py

@@ -10,6 +10,8 @@
 from jsonschema._utils import find_additional_properties
 from jsonschema.exceptions import FormatError
 from jsonschema.exceptions import ValidationError
+from jsonschema.exceptions import _WrappedReferencingError
+from referencing.exceptions import Unresolvable
 
 
 def handle_discriminator(
@@ -53,7 +55,15 @@ def handle_discriminator(
 
     try:
         validator._validate_reference(ref=ref, instance=instance)
-    except Exception:
+    except _WrappedReferencingError as error:
+        if isinstance(error.__cause__, Unresolvable):
+            yield ValidationError(
+                f"{instance!r} reference {ref!r} could not be resolved",
+                context=[],
+            )
+            return
+        raise
+    except Unresolvable:
         yield ValidationError(
             f"{instance!r} reference {ref!r} could not be resolved",
             context=[],

tests/integration/test_validators.py

@@ -1,4 +1,6 @@
 from base64 import b64encode
+from typing import Any
+from typing import cast
 
 import pytest
 from jsonschema import ValidationError
@@ -353,6 +355,57 @@ def test_oneof_required(self, validator_class):
         result = validator.validate(instance)
         assert result is None
 
+    def test_discriminator_does_not_swallow_unexpected_ref_errors(
+        self, monkeypatch
+    ):
+        schema = {
+            "$ref": "#/components/schemas/Route",
+            "components": {
+                "schemas": {
+                    "Route": {
+                        "oneOf": [
+                            {"$ref": "#/components/schemas/MountainHiking"}
+                        ],
+                        "discriminator": {
+                            "propertyName": "discipline",
+                            "mapping": {
+                                "mountain_hiking": "#/components/schemas/MountainHiking"
+                            },
+                        },
+                    },
+                    "MountainHiking": {
+                        "type": "object",
+                        "properties": {
+                            "discipline": {"type": "string"},
+                            "length": {"type": "integer"},
+                        },
+                        "required": ["discipline", "length"],
+                    },
+                },
+            },
+        }
+
+        def fail_validate_reference(*args: Any, **kwargs: Any) -> None:
+            raise RuntimeError("boom")
+
+        monkeypatch.setattr(
+            cast(Any, OAS30Validator),
+            "_validate_reference",
+            fail_validate_reference,
+        )
+
+        validator = OAS30Validator(
+            schema,
+            format_checker=oas30_format_checker,
+        )
+        with pytest.raises(RuntimeError, match="boom"):
+            validator.validate(
+                {
+                    "discipline": "mountain_hiking",
+                    "length": 10,
+                }
+            )
+
     @pytest.mark.parametrize(
         "schema_type",
         [