From 00d88388f84bd8372929dd3bb402019f8999b365 Mon Sep 17 00:00:00 2001
From: Vitor Hideyoshi <vitor.h.n.batista@gmail.com>
Date: Mon, 18 Aug 2025 23:33:16 -0300
Subject: [PATCH] Fixes Behavior of Pydantic None Type and Adds More Tests

---
 jambo/parser/null_type_parser.py      | 13 +++----------
 tests/parser/test_null_type_parser.py | 24 +++++-------------------
 tests/test_schema_converter.py        | 20 ++++++++++++++++++++
 3 files changed, 28 insertions(+), 29 deletions(-)

diff --git a/jambo/parser/null_type_parser.py b/jambo/parser/null_type_parser.py
index 35036ef..4c384f4 100644
--- a/jambo/parser/null_type_parser.py
+++ b/jambo/parser/null_type_parser.py
@@ -5,21 +5,14 @@ from typing_extensions import Unpack
 
 
 class NullTypeParser(GenericTypeParser):
-    mapped_type = None
+    mapped_type = type(None)
 
     json_schema_type = "type:null"
 
-    type_mappings = {
-        "default": "default",
-    }
-
     def from_properties_impl(
         self, name, properties, **kwargs: Unpack[TypeParserOptions]
     ):
         mapped_properties = self.mappings_properties_builder(properties, **kwargs)
+        mapped_properties["default"] = None
 
-        default_value = properties.get("default")
-        if default_value is not None:
-            raise ValueError(f"Default value for {name} must be None.")
-
-        return None, mapped_properties
+        return self.mapped_type, mapped_properties
diff --git a/tests/parser/test_null_type_parser.py b/tests/parser/test_null_type_parser.py
index 414fbae..e2732c0 100644
--- a/tests/parser/test_null_type_parser.py
+++ b/tests/parser/test_null_type_parser.py
@@ -13,31 +13,17 @@ class TestNullTypeParser(TestCase):
             "placeholder", properties
         )
 
-        self.assertEqual(type_parsing, None)
+        self.assertEqual(type_parsing, type(None))
         self.assertEqual(type_validator, {"default": None})
 
-    def test_null_parser_with_default(self):
+    def test_null_parser_with_invalid_default(self):
         parser = NullTypeParser()
 
-        properties = {
-            "type": "null",
-            "default": None,
-        }
+        properties = {"type": "null", "default": "invalid"}
 
         type_parsing, type_validator = parser.from_properties_impl(
             "placeholder", properties
         )
 
-        self.assertEqual(type_parsing, None)
-        self.assertEqual(type_validator["default"], None)
-
-    def test_null_parser_with_invalid_default(self):
-        parser = NullTypeParser()
-
-        properties = {
-            "type": "null",
-            "default": "invalid",
-        }
-
-        with self.assertRaises(ValueError):
-            parser.from_properties_impl("placeholder", properties)
+        self.assertEqual(type_parsing, type(None))
+        self.assertEqual(type_validator, {"default": None})
diff --git a/tests/test_schema_converter.py b/tests/test_schema_converter.py
index fbba3c9..6a1421d 100644
--- a/tests/test_schema_converter.py
+++ b/tests/test_schema_converter.py
@@ -657,3 +657,23 @@ class TestSchemaConverter(TestCase):
 
         with self.assertRaises(ValueError):
             Model(name="Canada")
+
+    def test_null_type_parser(self):
+        schema = {
+            "title": "Test",
+            "type": "object",
+            "properties": {
+                "a_thing": {"type": "null"},
+            },
+        }
+
+        Model = SchemaConverter.build(schema)
+
+        obj = Model()
+        self.assertIsNone(obj.a_thing)
+
+        obj = Model(a_thing=None)
+        self.assertIsNone(obj.a_thing)
+
+        with self.assertRaises(ValueError):
+            Model(a_thing="not none")