Fix one more Validator.evolve issue for downstream Validators.

Here for renamed attributes out of attrs-using classes.

Refs: '#982 (comment)'

Author: Julian

CHANGELOG.rst

@@ -1,3 +1,8 @@
+v4.10.2
+-------
+
+* Fix a second place where subclasses may have added attrs attributes (#982).
+
 v4.10.1
 -------
 

jsonschema/tests/test_validators.py

@@ -1488,12 +1488,14 @@ def test_evolve_with_subclass(self):
         @attr.s
         class OhNo(self.Validator):
             foo = attr.ib(factory=lambda: [1, 2, 3])
+            _bar = attr.ib(default=37)
 
-        validator = OhNo({})
+        validator = OhNo({}, bar=12)
         self.assertEqual(validator.foo, [1, 2, 3])
 
         new = validator.evolve(schema={"type": "integer"})
         self.assertEqual(new.foo, [1, 2, 3])
+        self.assertEqual(new._bar, 12)
 
     def test_it_delegates_to_a_legacy_ref_resolver(self):
         """

jsonschema/validators.py

@@ -202,12 +202,14 @@ def check_schema(cls, schema):
                 raise exceptions.SchemaError.create_from(error)
 
         def evolve(self, **changes):
-            schema = changes.setdefault("schema", self.schema)
-            NewValidator = validator_for(schema, default=self.__class__)
-
             # Essentially reproduces attr.evolve, but may involve instantiating
             # a different class than this one.
-            for field in attr.fields(Validator):
+            cls = self.__class__
+
+            schema = changes.setdefault("schema", self.schema)
+            NewValidator = validator_for(schema, default=cls)
+
+            for field in attr.fields(cls):
                 if not field.init:
                     continue
                 attr_name = field.name  # To deal with private attributes.