feat: support type alias

.github/workflows/ci.yaml

@@ -34,7 +34,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
         pydantic-version: ["1.10", "2.0"]
         sqla-version: ["1.4", "2"]
         exclude:

polyfactory/utils/helpers.py

@@ -8,7 +8,7 @@
 except ImportError:
     NoneType = type(None)  # type: ignore[misc,assignment]
 
-from typing_extensions import get_args, get_origin
+from typing_extensions import TypeAliasType, get_args, get_origin
 
 from polyfactory.constants import TYPE_MAPPING
 from polyfactory.utils.predicates import is_annotated, is_new_type, is_optional, is_safe_subclass, is_union
@@ -65,13 +65,20 @@ def unwrap_annotation(annotation: Any, random: Random) -> Any:
     :returns: The unwrapped annotation.
 
     """
-    while is_optional(annotation) or is_new_type(annotation) or is_annotated(annotation):
+    while (
+        is_optional(annotation)
+        or is_new_type(annotation)
+        or is_annotated(annotation)
+        or isinstance(annotation, TypeAliasType)
+    ):
         if is_new_type(annotation):
             annotation = unwrap_new_type(annotation)
         elif is_optional(annotation):
             annotation = unwrap_optional(annotation)
         elif is_annotated(annotation):
             annotation = unwrap_annotated(annotation, random=random)[0]
+        elif isinstance(annotation, TypeAliasType):
+            annotation = annotation.__value__
 
     return annotation
 

polyfactory/utils/predicates.py

@@ -3,15 +3,7 @@
 from inspect import isclass
 from typing import Any, Literal, NewType, Optional, TypeVar, Union, get_args
 
-from typing_extensions import (
-    Annotated,
-    NotRequired,
-    ParamSpec,
-    Required,
-    TypeGuard,
-    _AnnotatedAlias,
-    get_origin,
-)
+from typing_extensions import Annotated, NotRequired, ParamSpec, Required, TypeGuard, _AnnotatedAlias, get_origin
 
 from polyfactory.constants import TYPE_MAPPING
 

tests/test_new_types.py

@@ -1,6 +1,8 @@
+import sys
 from datetime import date
 from decimal import Decimal
-from typing import Any, Dict, List, NewType, Optional, Tuple, Union
+from types import ModuleType
+from typing import Any, Callable, Dict, List, NewType, Optional, Tuple, Union
 
 import pytest
 from pydantic import (
@@ -18,6 +20,7 @@
     constr,
 )
 
+from polyfactory.factories.dataclass_factory import DataclassFactory
 from polyfactory.factories.pydantic_factory import ModelFactory
 
 
@@ -137,3 +140,25 @@ class MyFactory(ModelFactory):
 
     assert isinstance(result.conpositive_float_field, float)
     assert result.conpositive_float_field > 0
+
+
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="3.12 only syntax")
+def test_type_alias(create_module: Callable[[str], ModuleType]) -> None:
+    module = create_module(
+        """
+from typing import Literal
+from dataclasses import dataclass
+
+
+type LiteralAlias = Literal["a", "b"]
+
+
+@dataclass
+class A:
+    field: LiteralAlias
+""",
+    )
+
+    factory = DataclassFactory.create_factory(module.A)  # type: ignore[var-annotated]
+    result = factory.build()
+    assert result.field in {"a", "b"}