Bug: RecursionError With constrained 0 length lists

[tom300z]

Description

When constraining a list to be empty (max_length=0):

from pydantic import BaseModel, Field
from polyfactory.factories.pydantic_factory import ModelFactory
class TestModel(BaseModel):
    empty_list_field: list = Field(default=[], max_length=0)

class TestModelFactory(ModelFactory):
    __model__ = TestModel

TestModelFactory.build()

a recursion error occurs.

The problem seems to be in

polyfactory/polyfactory/value_generators/constrained_collections.py

Line 49 in 67c5720

length = factory.__random__.randint(min_items, max_items) or 1

where a default length of 1 is used if the randomly picked length (always 0) is falsy. @Goldziher do you remember why this default exists?

URL to code causing the issue

No response

MCVE

from pydantic import BaseModel, Field
from polyfactory.factories.pydantic_factory import ModelFactory
class TestModel(BaseModel):
    empty_list_field: list = Field(default=[], max_length=0)

class TestModelFactory(ModelFactory):
    __model__ = TestModel

TestModelFactory.build()

Steps to reproduce

1. Install polyfactory & pydantic (v2)
2. Run example code

Screenshots

No response

Logs

No response

Release Version

v2.16.2

Platform

• Linux
• Mac
• Windows
• Other (Please specify in the description above)

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[guacs]

@tom300z thanks for reporting this! I checked, and I couldn't really see a good reason to have it default to 1. Some of the tests check that the length of the collection from handle_constrained_collection is greater than 0, but I think that's incorrect. It should be checking that the length is greater than or equal to 0. If I make that change, the tests are all passing as well. So I think it should be fine to not default to 1 even if the random length we get is 0.