Issue with pytest-asyncio <> testcontainers postgres <> pytest-django

[0xRaduan]

I've hit an issue where basically my setup is:

• have an async test that tries to create some things in a postgres database running locally via testcontainers
• use pytest-asyncio + testcontainers postgres + pytest django
• if I run things synchronously, everything works(migrations are properly created, postgres spawned,
• When I run things async, my migrations are never applied.
• I think it's some weird connection between pytest-asyncio <> pytest-django <> the way django + postgresql works.

This issue is meant as a discussion on what is the right setup, perhaps some users can share.

@pytest.fixture(scope="session")
def postgresql_proc():
    with PostgresContainer("postgres:15") as pg:
        raw_url = pg.get_connection_url()
        clean_url = raw_url.replace("postgresql+psycopg2://", "postgresql://")
        cfg = dj_database_url.config(default=clean_url)
        proc = SimpleNamespace(
            host=pg.get_container_host_ip(),
            port=int(pg.get_exposed_port(pg.port)),
            user=cfg["USER"],
            password=cfg["PASSWORD"],
            dbname=cfg["NAME"],
            stop=pg.stop,
        )

        yield proc


@pytest.fixture(scope="session")
def django_db_modify_db_settings(postgresql_proc):
    from django.conf import settings

    cfg = settings.DATABASES["default"]
    cfg.update(
        {
            "ENGINE": "django.db.backends.postgresql",
            "HOST": postgresql_proc.host,
            "PORT": postgresql_proc.port,
            "NAME": postgresql_proc.dbname,
            "USER": postgresql_proc.user,
            "PASSWORD": postgresql_proc.password,
            "CONN_MAX_AGE": 600,
            "CONN_HEALTH_CHECKS": True,
            "DISABLE_SERVER_SIDE_CURSORS": True,
        }
    )
    cfg["TEST"]["NAME"] = "test"
    settings.DATABASES["default"] = cfg
    print(settings.DATABASES["default"])

And then here is a dummy test:

from auth.models import User


@pytest.mark.asyncio
@pytest.mark.django_db
async def test_migration_plan():
    out = StringIO()
    await sync_to_async(call_command)(
        "showmigrations", "--plan", stdout=out, verbosity=1
    )
    print("\n=== MIGRATION PLAN ===\n", out.getvalue())

    recorder = MigrationRecorder(connection)
    applied = await sync_to_async(recorder.applied_migrations)()
    print(
        "\n=== APPLIED MIGRATIONS ===\n",
        "\n".join(f"{app}.{name}" for app, name in applied),
    )

    tables = connection.introspection.table_names()
    print("\n=== TABLES IN SCHEMA ===\n", tables)
    await DefaultUserFactory() # <----- this fails in async saying user database is not present. works perfectly in sync.
    print(User.objects.count())

---

Let me know if that's not the right forum, and I am happy to move this to pytest-django perhaps

[seifertm]

There's an existing issue about database migrations in conjunction with pytest-django: #226
I think the two are related.

@0xRaduan If you can provide a more complete reproducer (for example with all the Django-related files, docker-compose or similar for starting Postgres, Django migrations…) I'm happy to look into it.