Fix error paths when additionalItems is used with items keyword. fix #122

Author: gazpachoking

jsonschema/_validators.py

@@ -59,9 +59,10 @@ def additionalItems(validator, aI, instance, schema):
     ):
         return
 
+    len_items = len(schema.get("items", []))
     if validator.is_type(aI, "object"):
-        for index, item in enumerate(instance[len(schema.get("items", [])):]):
-            for error in validator.descend(item, aI, path=index):
+        for index, item in enumerate(instance[len_items:]):
+            for error in validator.descend(item, aI, path=index+len_items):
                 yield error
     elif not aI and len(instance) > len(schema.get("items", [])):
         error = "Additional items are not allowed (%s %s unexpected)"

jsonschema/tests/test_validators.py

@@ -484,18 +484,18 @@ def test_patternProperties(self):
         self.assertEqual(e2.validator, "minimum")
 
     def test_additionalItems(self):
-        instance = ["foo", 1]
+        instance = ["foo", "bar", 1]
         schema = {
-            "items": [],
+            "items": [{}],
             "additionalItems" : {"type": "integer", "minimum": 5}
         }
 
         validator = Draft3Validator(schema)
         errors = validator.iter_errors(instance)
         e1, e2 = sorted_errors(errors)
 
-        self.assertEqual(list(e1.path), [0])
-        self.assertEqual(list(e2.path), [1])
+        self.assertEqual(list(e1.path), [1])
+        self.assertEqual(list(e2.path), [2])
 
         self.assertEqual(e1.validator, "type")
         self.assertEqual(e2.validator, "minimum")