Bug: When setting size=0, 1 instance is created and not put in a list

[Danielius5]

Hello, I am not sure if this is intended behavior or undefined behavior, but using Fixture with size=random.randint(0, 200) has caused us a bit of trouble.

Instead of giving back an empty list (what we assumed), when size=0, Fixture still returns 1 instance of the model and does not put it in the list. I created a sample example code of what we have:

from pydantic import BaseModel
from pydantic_factories import ModelFactory
from pydantic_factories.fields import Fixture
from pydantic_factories.plugins.pytest_plugin import register_fixture


class TestSubModel(BaseModel):
    ...

class TestModel(BaseModel):
    submodels: list[TestSubModel]

@register_fixture
class TestSubModelFactory(ModelFactory[TestSubModel]):
    __model__ = TestSubModel

@register_fixture
class TestModelFactory(ModelFactory[TestModel]):
    __model__ = TestModel

    submodels = Fixture(TestSubModelFactory, size=1) # change to 0 to get test failing


def test_factory(test_model_factory: TestModelFactory):
    TestModel.parse_obj(test_model_factory.build().dict())

when changed 1 to 0 you should get:

>   ???
E   pydantic.error_wrappers.ValidationError: 1 validation error for TestModel
E   submodels
E     value is not a valid list (type=type_error.list)

To my understanding, allowing to return an empty list on size=0 would be very useful as it would allow to check the edge case of no submodels. Maybe we are doing something wrong?

[Goldziher]

Hi. Yes, this seems to be a bug. I'll include a fix for this in 2.0