fix: Adjust min/max items to valid lengths for Set[Enum] fields (#567)

Co-authored-by: guacs <126393040+guacs@users.noreply.github.com>

polyfactory/value_generators/constrained_collections.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any, Callable, List, Mapping, TypeVar, cast
+from enum import EnumMeta
+from typing import TYPE_CHECKING, Any, Callable, List, Literal, Mapping, TypeVar, cast
 
 from polyfactory.exceptions import ParameterException
 from polyfactory.field_meta import FieldMeta
@@ -43,6 +44,16 @@ def handle_constrained_collection(
         msg = "max_items must be larger or equal to min_items"
         raise ParameterException(msg)
 
+    if collection_type in (frozenset, set) or unique_items:
+        max_field_values = max_items
+        if hasattr(field_meta.annotation, "__origin__") and field_meta.annotation.__origin__ is Literal:
+            if field_meta.children is not None:
+                max_field_values = len(field_meta.children)
+        elif isinstance(field_meta.annotation, EnumMeta):
+            max_field_values = len(field_meta.annotation)
+        min_items = min(min_items, max_field_values)
+        max_items = min(max_items, max_field_values)
+
     collection: set[T] | list[T] = set() if (collection_type in (frozenset, set) or unique_items) else []
 
     try:

tests/test_collection_length.py

@@ -1,10 +1,13 @@
-from typing import Any, Dict, List, Optional, Set, Tuple
+from enum import Enum
+from typing import Any, Dict, FrozenSet, List, Literal, Optional, Set, Tuple, get_args
 
 import pytest
 
+from pydantic import BaseModel
 from pydantic.dataclasses import dataclass
 
 from polyfactory.factories import DataclassFactory
+from polyfactory.factories.pydantic_factory import ModelFactory
 
 MIN_MAX_PARAMETERS = ((10, 15), (20, 25), (30, 40), (40, 50))
 
@@ -132,3 +135,50 @@ class FooFactory(DataclassFactory[Foo]):
 
         assert len(foo.foo) >= min_val, len(foo.foo)
         assert len(foo.foo) <= max_val, len(foo.foo)
+
+
+@pytest.mark.parametrize("type_", (List, FrozenSet, Set))
+@pytest.mark.parametrize("min_items", (0, 2, 4))
+@pytest.mark.parametrize("max_inc", (0, 1, 4))
+def test_collection_length_with_literal(type_: type, min_items: int, max_inc: int) -> None:
+    max_items = min_items + max_inc
+    literal_type = Literal["Dog", "Cat", "Monkey"]
+
+    @dataclass
+    class MyModel:
+        animal_collection: type_[literal_type]  # type: ignore
+
+    class MyFactory(DataclassFactory):
+        __model__ = MyModel
+        __randomize_collection_length__ = True
+        __min_collection_length__ = min_items
+        __max_collection_length__ = max_items
+
+    result = MyFactory.build()
+    assert len(result.animal_collection) >= min(min_items, len(get_args(literal_type)))
+    assert len(result.animal_collection) <= max_items
+
+
+@pytest.mark.parametrize("type_", (List, FrozenSet, Set))
+@pytest.mark.parametrize("min_items", (0, 2, 4))
+@pytest.mark.parametrize("max_inc", (0, 1, 4))
+def test_collection_length_with_enum(type_: type, min_items: int, max_inc: int) -> None:
+    max_items = min_items + max_inc
+
+    class Animal(str, Enum):
+        DOG = "Dog"
+        CAT = "Cat"
+        MONKEY = "Monkey"
+
+    class MyModel(BaseModel):
+        animal_collection: type_[Animal]  # type: ignore
+
+    class MyFactory(ModelFactory):
+        __model__ = MyModel
+        __randomize_collection_length__ = True
+        __min_collection_length__ = min_items
+        __max_collection_length__ = max_items
+
+    result = MyFactory.build()
+    assert len(result.animal_collection) >= min(min_items, len(Animal))
+    assert len(result.animal_collection) <= max_items