fix: constrained strings not deterministic with seed because urandom …

…not seedable (#319)

* urandom not seedable

* compatibility python 3.8

* python 38 has getrandbits bug

---------

Co-authored-by: An De Rijdt <an.joanna.de.rijdt@ing.com>

polyfactory/value_generators/primitives.py

@@ -2,7 +2,6 @@
 
 from binascii import hexlify
 from decimal import Decimal
-from os import urandom
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
@@ -80,7 +79,7 @@ def create_random_bytes(
         max_length = min_length + 1 * 2
 
     length = random.randint(min_length, max_length)
-    result = hexlify(urandom(length))
+    result = b"" if length == 0 else hexlify(random.getrandbits(length * 8).to_bytes(length, "little"))
 
     if lower_case:
         result = result.lower()

tests/test_random_seed.py

@@ -40,3 +40,19 @@ class FactoryWithNoneOptionals(ModelFactory):
     ModelFactory.seed_random(seed)
     second_build = [FactoryWithNoneOptionals.build() for _ in range(10)]
     assert first_build == second_build
+
+
+def test_deterministic_constrained_strings() -> None:
+    class MyModel(BaseModel):
+        id: int
+        special_id: str = Field(min_length=10, max_length=24)
+
+    class MyModelFactory(ModelFactory):
+        __model__ = MyModel
+
+    ModelFactory.seed_random(1651)
+
+    ins = MyModelFactory.build()
+
+    assert ins.id == 4
+    assert ins.special_id == "48489ab53c59b24acfe1"