Improve the hashability of referencing exceptions when they contain hashable data.

Closes: #1126

Author: Julian

CHANGELOG.rst

@@ -1,3 +1,8 @@
+v4.18.4
+=======
+
+* Improve the hashability of wrapped referencing exceptions when they contain hashable data.
+
 v4.18.3
 =======
 

jsonschema/exceptions.py

@@ -230,6 +230,9 @@ def __eq__(self, other):
     def __getattr__(self, attr):
         return getattr(self._wrapped, attr)
 
+    def __hash__(self):
+        return hash(self._wrapped)
+
     def __repr__(self):
         return f"<WrappedReferencingError {self._wrapped!r}>"
 

jsonschema/tests/test_deprecations.py

@@ -211,6 +211,24 @@ def test_catching_Unresolvable_via_RefResolutionError(self):
             (u.exception, "Unresolvable: urn:nothing")
         )
 
+    def test_WrappedReferencingError_hashability(self):
+        """
+        Ensure the wrapped referencing errors are hashable when possible.
+        """
+        with self.assertWarns(DeprecationWarning):
+            from jsonschema import RefResolutionError
+
+        validator = validators.Draft202012Validator({"$ref": "urn:nothing"})
+
+        with self.assertRaises(referencing.exceptions.Unresolvable) as u:
+            validator.validate(12)
+
+        with self.assertRaises(RefResolutionError) as e:
+            validator.validate(12)
+
+        self.assertIn(e.exception, {u.exception})
+        self.assertIn(u.exception, {e.exception})
+
     def test_Validator_subclassing(self):
         """
         As of v4.12.0, subclassing a validator class produces an explicit