No parameters generated for model-only attributres

No parameters are generated for model-only parameters. We often have Django model defaults which we don't override in factories, but do override in tests. For example:

class Book(models.Model):
    title = models.CharField(max_length=255, default='My title')


class BookFactory(factory.DjangoModelFactory):
    class Meta:
        model = Book


register(BookFactory)


@pytest.mark.django_db
@pytest.mark.parametrize('book__title', ['My other title'])
def test_title(book):
    assert book.title == 'My other title'

This results in ValueError: <function test_title at 0x7efe970a2488> uses no fixture 'book__title'

If I add the title to the BookFactory it does work.

Result of pip freeze:

Django==1.9.6
factory-boy==2.7.0
fake-factory==0.5.7
inflection==0.3.1
ipaddress==1.0.16
py==1.4.31
pytest==2.9.1
pytest-django==2.9.1
pytest-factoryboy==1.1.6
python-dateutil==2.5.3
six==1.10.0

No source file or test is named. Start by reproducing the Django model-only attribute example from the issue and tracing how pytest-factoryboy discovers factory parameters. Done means the parametrized book__title fixture is generated and the example test passes without adding title to BookFactory.