Fix items/prefixItems' message when used with heterogeneous arrays.

Closes: #1157

CHANGELOG.rst

@@ -1,3 +1,8 @@
+v4.19.2
+=======
+
+* Fix the error message for additional items when used with heterogeneous arrays.
+
 v4.19.1
 =======
 

jsonschema/_keywords.py

@@ -54,7 +54,7 @@ def additionalProperties(validator, aP, instance, schema):
             yield ValidationError(error)
         else:
             error = "Additional properties are not allowed (%s %s unexpected)"
-            yield ValidationError(error % extras_msg(extras))
+            yield ValidationError(error % extras_msg(sorted(extras, key=str)))
 
 
 def items(validator, items, instance, schema):
@@ -63,9 +63,17 @@ def items(validator, items, instance, schema):
 
     prefix = len(schema.get("prefixItems", []))
     total = len(instance)
-    if items is False and total > prefix:
-        message = f"Expected at most {prefix} items, but found {total}"
-        yield ValidationError(message)
+    extra = total - prefix
+    if extra <= 0:
+        return
+
+    if items is False:
+        rest = instance[prefix:] if extra != 1 else instance[prefix]
+        item = "items" if prefix != 1 else "item"
+        yield ValidationError(
+            f"Expected at most {prefix} {item} but found {extra} "
+            f"extra: {rest!r}",
+        )
     else:
         for index in range(prefix, total):
             yield from validator.descend(
@@ -427,7 +435,8 @@ def unevaluatedProperties(validator, unevaluatedProperties, instance, schema):
     if unevaluated_keys:
         if unevaluatedProperties is False:
             error = "Unevaluated properties are not allowed (%s %s unexpected)"
-            yield ValidationError(error % extras_msg(unevaluated_keys))
+            extras = sorted(unevaluated_keys, key=str)
+            yield ValidationError(error % extras_msg(extras))
         else:
             error = (
                 "Unevaluated properties are not valid under "

jsonschema/_utils.py

@@ -91,7 +91,7 @@ def extras_msg(extras):
     """
 
     verb = "was" if len(extras) == 1 else "were"
-    return ", ".join(repr(extra) for extra in sorted(extras)), verb
+    return ", ".join(repr(extra) for extra in extras), verb
 
 
 def ensure_list(thing):

jsonschema/tests/test_validators.py

@@ -510,11 +510,24 @@ def test_maxItems(self):
         self.assertEqual(message, "[1, 2, 3] is too long")
 
     def test_prefixItems_with_items(self):
+        message = self.message_for(
+            instance=[1, 2, "foo"],
+            schema={"items": False, "prefixItems": [{}, {}]},
+        )
+        self.assertEqual(
+            message,
+            "Expected at most 2 items but found 1 extra: 'foo'"
+        )
+
+    def test_prefixItems_with_multiple_extra_items(self):
         message = self.message_for(
             instance=[1, 2, "foo", 5],
             schema={"items": False, "prefixItems": [{}, {}]},
         )
-        self.assertEqual(message, "Expected at most 2 items, but found 4")
+        self.assertEqual(
+            message,
+            "Expected at most 2 items but found 2 extra: ['foo', 5]"
+        )
 
     def test_minLength(self):
         message = self.message_for(
@@ -655,7 +668,7 @@ def test_unevaluated_items(self):
         message = self.message_for(instance=["foo", "bar"], schema=schema)
         self.assertIn(
             message,
-            "Unevaluated items are not allowed ('bar', 'foo' were unexpected)",
+            "Unevaluated items are not allowed ('foo', 'bar' were unexpected)",
         )
 
     def test_unevaluated_items_on_invalid_type(self):
@@ -702,6 +715,79 @@ def test_unevaluated_properties_on_invalid_type(self):
         message = self.message_for(instance="foo", schema=schema)
         self.assertEqual(message, "'foo' is not of type 'object'")
 
+    def test_single_item(self):
+        schema = {"prefixItems": [{}], "items": False}
+        message = self.message_for(
+            instance=["foo", "bar", "baz"],
+            schema=schema,
+        )
+        self.assertEqual(
+            message,
+            "Expected at most 1 item but found 2 extra: ['bar', 'baz']",
+        )
+
+    def test_heterogeneous_additionalItems_with_Items(self):
+        schema = {"items": [{}], "additionalItems": False}
+        message = self.message_for(
+            instance=["foo", "bar", 37],
+            schema=schema,
+            cls=validators.Draft7Validator,
+        )
+        self.assertEqual(
+            message,
+            "Additional items are not allowed ('bar', 37 were unexpected)"
+        )
+
+    def test_heterogeneous_items_prefixItems(self):
+        schema = {"prefixItems": [{}], "items": False}
+        message = self.message_for(
+            instance=["foo", "bar", 37],
+            schema=schema,
+        )
+        self.assertEqual(
+            message,
+            "Expected at most 1 item but found 2 extra: ['bar', 37]",
+        )
+
+    def test_heterogeneous_unevaluatedItems_prefixItems(self):
+        schema = {"prefixItems": [{}], "unevaluatedItems": False}
+        message = self.message_for(
+            instance=["foo", "bar", 37],
+            schema=schema,
+        )
+        self.assertEqual(
+            message,
+            "Unevaluated items are not allowed ('bar', 37 were unexpected)",
+        )
+
+    def test_heterogeneous_properties_additionalProperties(self):
+        """
+        Not valid deserialized JSON, but this should not blow up.
+        """
+        schema = {"properties": {"foo": {}}, "additionalProperties": False}
+        message = self.message_for(
+            instance={"foo": {}, "a": "baz", 37: 12},
+            schema=schema,
+        )
+        self.assertEqual(
+            message,
+            "Additional properties are not allowed (37, 'a' were unexpected)",
+        )
+
+    def test_heterogeneous_properties_unevaluatedProperties(self):
+        """
+        Not valid deserialized JSON, but this should not blow up.
+        """
+        schema = {"properties": {"foo": {}}, "unevaluatedProperties": False}
+        message = self.message_for(
+            instance={"foo": {}, "a": "baz", 37: 12},
+            schema=schema,
+        )
+        self.assertEqual(
+            message,
+            "Unevaluated properties are not allowed (37, 'a' were unexpected)",
+        )
+
 
 class TestValidationErrorDetails(TestCase):
     # TODO: These really need unit tests for each individual keyword, rather