Automatically define factory boy recipes for dataclasses by inspecting the type annotations

autofactory.py

## See https://github.com/FactoryBoy/factory_boy/issues/836
import inspect
from typing import Literal, get_args, get_origin
import factory
import factory.fuzzy
from dataclasses import Field, MISSING, is_dataclass
from enum import Enum
from datetime import date, datetime

def get_auto_field(field: Field):
    if field.default is not MISSING:
        return field.default
    elif field.type is str and 'email' in field.name:
        return factory.Faker("ascii_email")
    elif field.type is datetime:
        return factory.Faker("date_time_between")
    elif field.type is date:
        return factory.Faker("date_object")
    elif is_dataclass(field.type):
        # fixme reflect the factory un a better way than eval
        return factory.SubFactory(eval(f'{field.type.__name__}AutoFactory'))
    elif inspect.isclass(field.type) and issubclass(field.type, Enum):
        return factory.fuzzy.FuzzyChoice(field.type.__members__.values())
    elif get_origin(field.type) in [list, tuple, set]:
        args = get_args(field.type)
        return factory.Faker(f'py{get_origin(field.type).__name__}', value_types=args)
    elif get_origin(field.type) is Literal:
        args = get_args(field.type)
        return factory.fuzzy.FuzzyChoice(args)

    # str, int, float, decimal
    return factory.Faker(f'py{field.type.__name__.lower()}')


def auto_factory(target_model, field_overrides=None):
    factory_name = f'{target_model.__name__}AutoFactory'
    class Meta:
        model = target_model

    attrs = {name: get_auto_field(field) for name, field in target_model.__dataclass_fields__.items()}
    attrs.update(field_overrides or {})
    attrs['Meta'] = Meta

    return type(factory_name, (factory.Factory,), attrs)

Adds support for Literal fields.