nullable implementation based on clarified OAS 3.0.3 definition

Author: p1c2u

openapi_schema_validator/_validators.py

@@ -18,30 +18,6 @@
 from jsonschema.protocols import Validator
 
 
-def include_nullable_validator(
-    schema: Dict[Hashable, Any]
-) -> ItemsView[Hashable, Any]:
-    """
-    Include ``nullable`` validator always.
-    Suitable for use with `create`'s ``applicable_validators`` argument.
-    """
-    _schema = deepcopy(schema)
-
-    # append defaults to trigger nullable validator, except where $ref in the schema checks null
-    if "nullable" not in _schema \
-            and "$ref" not in _schema \
-            and "oneOf" not in _schema \
-            and "anyOf" not in _schema \
-            and "allOf" not in _schema:
-        _schema.update(
-            {
-                "nullable": False,
-            }
-        )
-
-    return _schema.items()
-
-
 def handle_discriminator(
     validator: Validator, _: Any, instance: Any, schema: Mapping[Hashable, Any]
 ) -> Iterator[ValidationError]:
@@ -131,7 +107,14 @@ def type(
     schema: Mapping[Hashable, Any],
 ) -> Iterator[ValidationError]:
     if instance is None:
-        return
+        # nullable implementation based on OAS 3.0.3
+        # * nullable is only meaningful if its value is true
+        # * nullable: true is only meaningful in combination with a type
+        #   assertion specified in the same Schema Object.
+        # * nullable: true operates within a single Schema Object
+        if "nullable" in schema and schema["nullable"] == True:
+            return
+        yield ValidationError("None for not nullable")
 
     if not validator.is_type(instance, data_type):
         data_repr = repr(data_type)
@@ -167,16 +150,6 @@ def items(
         yield from validator.descend(item, items, path=index)
 
 
-def nullable(
-    validator: Validator,
-    is_nullable: bool,
-    instance: Any,
-    schema: Mapping[Hashable, Any],
-) -> Iterator[ValidationError]:
-    if instance is None and not is_nullable:
-        yield ValidationError("None for not nullable")
-
-
 def required(
     validator: Validator,
     required: List[str],

openapi_schema_validator/validators.py

@@ -45,7 +45,6 @@
         # TODO: adjust default
         "$ref": _validators.ref,
         # fixed OAS fields
-        "nullable": oas_validators.nullable,
         "discriminator": oas_validators.not_implemented,
         "readOnly": oas_validators.readOnly,
         "writeOnly": oas_validators.writeOnly,
@@ -59,7 +58,6 @@
     # See https://github.com/p1c2u/openapi-schema-validator/pull/12
     # version="oas30",
     id_of=lambda schema: schema.get("id", ""),
-    applicable_validators=oas_validators.include_nullable_validator,
 )
 
 OAS31Validator = extend(

tests/integration/test_validators.py

@@ -31,6 +31,16 @@ def test_null(self, schema_type):
         with pytest.raises(ValidationError):
             validator.validate(value)
 
+    @pytest.mark.parametrize("is_nullable", [True, False])
+    def test_nullable_untyped(self, is_nullable):
+        schema = {"nullable": is_nullable}
+        validator = OAS30Validator(schema)
+        value = None
+
+        result = validator.validate(value)
+
+        assert result is None
+
     @pytest.mark.parametrize(
         "schema_type",
         [
@@ -50,6 +60,23 @@ def test_nullable(self, schema_type):
 
         assert result is None
 
+    def test_nullable_enum_without_none(self):
+        schema = {"type": "integer", "nullable": True, "enum": [1, 2, 3]}
+        validator = OAS30Validator(schema)
+        value = None
+
+        with pytest.raises(ValidationError):
+            validator.validate(value)
+
+    def test_nullable_enum_with_none(self):
+        schema = {"type": "integer", "nullable": True, "enum": [1, 2, 3, None]}
+        validator = OAS30Validator(schema)
+        value = None
+
+        result = validator.validate(value)
+
+        assert result is None
+
     @pytest.mark.parametrize(
         "value",
         [