diff --git a/.gitignore b/.gitignore
index 14a680a..8a082ed 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,3 +11,4 @@ venv
 *venv*
 .tox/
 dist/
+build/
diff --git a/development_utilities/gen_unit_test_template.py b/development_utilities/gen_unit_test_template.py
index 93e2b03..87bddc9 100644
--- a/development_utilities/gen_unit_test_template.py
+++ b/development_utilities/gen_unit_test_template.py
@@ -1,5 +1,6 @@
 import datetime
 import json
+import os
 from enum import Enum
 import inspect
 import pprint
@@ -17,6 +18,7 @@
 import uuid
 
 import pydantic
+from pydantic.types import AwareDatetime
 
 from s2python import frbc
 from s2python.common import Duration, PowerRange, NumberRange
@@ -64,7 +66,7 @@ def get_list_arg(field_type):
 
 
 def is_enum(field_type):
-    return issubclass(field_type, Enum)
+    return inspect.isclass(field_type) and issubclass(field_type, Enum)
 
 
 def snake_case(camelcased: str) -> str:
@@ -111,7 +113,8 @@ def generate_json_test_data_for_field(field_type: Type):
         value = bool(random.randint(0, 1))
     elif field_type is float:
         value = random.random() * 9000.0
-    elif field_type is datetime.datetime:
+    elif field_type in (AwareDatetime, datetime.datetime):
+        # Generate a timezone-aware datetime
         value = datetime.datetime(
             year=random.randint(2020, 2023),
             month=random.randint(1, 12),
@@ -119,9 +122,7 @@ def generate_json_test_data_for_field(field_type: Type):
             hour=random.randint(0, 23),
             minute=random.randint(0, 59),
             second=random.randint(0, 59),
-            tzinfo=datetime.timezone(
-                offset=datetime.timedelta(hours=random.randint(0, 2))
-            ),
+            tzinfo=datetime.timezone(datetime.timedelta(hours=random.randint(-12, 14))),
         )
     elif field_type is uuid.UUID:
         value = uuid.uuid4()
@@ -167,12 +168,19 @@ def dump_test_data_as_constructor_field_for(test_data, field_type: Type) -> str:
         value = str(test_data)
     elif field_type is float:
         value = str(test_data)
-    elif field_type is datetime.datetime:
+    elif field_type is AwareDatetime or field_type is datetime.datetime:
         test_data: datetime.datetime
         offset: datetime.timedelta = test_data.tzinfo.utcoffset(None)
-        value = f"datetime(year={test_data.year}, month={test_data.month}, day={test_data.day}, hour={test_data.hour}, minute={test_data.minute}, second={test_data.second}, tzinfo=offset(offset=timedelta(seconds={offset.total_seconds()})))"
+        value = (
+            f"datetime("
+            f"year={test_data.year}, month={test_data.month}, day={test_data.day}, "
+            f"hour={test_data.hour}, minute={test_data.minute}, second={test_data.second}, "
+            f"tzinfo=offset(offset=timedelta(seconds={offset.total_seconds()})))"
+        )
     elif field_type is uuid.UUID:
         value = f'uuid.UUID("{test_data}")'
+    elif type(field_type).__name__ == "_LiteralGenericAlias":
+        value = field_type.__args__[0]
     else:
         raise RuntimeError(
             f"Please implement dump test data for field type {field_type}"
@@ -217,11 +225,13 @@ def dump_test_data_as_json_field_for(test_data, field_type: Type):
         value = test_data
     elif field_type is float:
         value = test_data
-    elif field_type is datetime.datetime:
+    elif field_type in (AwareDatetime, datetime.datetime):
         test_data: datetime.datetime
         value = test_data.isoformat()
     elif field_type is uuid.UUID:
         value = str(test_data)
+    elif type(field_type).__name__ == "_LiteralGenericAlias":
+        value = test_data
     else:
         raise RuntimeError(
             f"Please implement dump test data to json for field type {field_type}"
@@ -294,7 +304,10 @@ def test__to_json__happy_path_full(self):
         print()
         print()
 
-        with open(
-            f"tests/unit/frbc/{snake_case(class_name)}_test.py", "w+"
-        ) as unit_test_file:
-            unit_test_file.write(template)
+        # Check if the file already exists
+        if not os.path.exists(f"tests/unit/frbc/{snake_case(class_name)}_test.py"):
+            with open(
+                f"tests/unit/frbc/{snake_case(class_name)}_test.py", "w+"
+            ) as unit_test_file:
+                unit_test_file.write(template)
+                print(f"Created tests/unit/frbc/{snake_case(class_name)}_test.py")