Fix random generation of ContentType values when there is no database access

[ento]

Context

I wrote a test in pytest that does:

baker.prepare(SomeModel, _fill_optional=True)

and it failed with:

RuntimeError: Database access not allowed, use the "django_db" mark, or the "db" or "transactional_db" fixtures to enable it.

model_bakery was trying to generate a ContentType value to fill in with and the first thing it does is to fetch a random value from the database:

path/to/venv/lib/python3.7/site-packages/model_bakery/random_gen.py:208: in gen_content_type
    return ContentType.objects.get_for_model(choice(apps.get_models()))

The gen_content_type() function tries to remediate when database access is not available:
https://github.com/model-bakers/model_bakery/blob/1.4.0/model_bakery/random_gen.py#L207-L211

    try:
        return ContentType.objects.get_for_model(choice(apps.get_models()))
    except AssertionError:
        warnings.warn("Database access disabled, returning ContentType raw instance")
        return ContentType()

But in the case of pytest-django, a RuntimeError is raised, not an AssertionError: https://github.com/pytest-dev/pytest-django/blob/v4.5.2/pytest_django/plugin.py#L709-L713

What this PR does

This PR adds RuntimeError to the exception classes that are caught by the try-except block in gen_content_type().

[berinhard]

Hi @ento! Thanks for opening your PR and contributing with model-bakery!

The code looks fine and it's good for me. Thanks for adding tests as well. Although I liked it, we can't merge your PR yet because there are some conflicts which are preventing the CI to run. Can you update your local main branch with the most up to date version and merge it into yours fix branch? That way the CI actions will be triggered and we'll feel more confident about merging your code.

We'd love to make it into the next 1.5.0 release =)

[ento]

Can you update your local main branch with the most up to date version and merge it into yours fix branch? That way the CI actions will be triggered and we'll feel more confident about merging your code.

👍 Done. Although it looks like we need a manual approval to run the CI checks, as this is my first PR against this repo.

[berinhard]

Hi @ento! The tests are running now, but it seems one of them is failing:

  tests/test_baker.py:622: in test_create_model_with_contenttype_field
      dummy = baker.prepare(models.DummyGenericForeignKeyModel)
  E   Failed: DID NOT WARN. No warnings of type (<class 'UserWarning'>,) were emitted. The list of emitted warnings is: [].

[ento]

@berinhard Pushed a fix. Good thing it failed in that run, as the failure was a flaky one in nature.