Running tests fails when DATABASES['default'] = {}

[Thomas Recouvreux]

On Django 1.7.x the management command test fails when DATABASES['default'] = {} with AttributeError: 'DatabaseWrapper' object has no attribute 'Database'.
This failure is also present on 1.7.3 and 1.7.4 version of Django.

To reproduce the problem:

1. Create a new project
2. Edit the settings.py this way:

DATABASES = {
    'default': {},
    'mysite': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db_mysite.sqlite3'),
    }
}

3. Add a dummy test to yout project, for example:

from django.test import TestCase


class MyTestCase(TestCase):
    def test_pouet(self):
        pass

4. Run python manage.py test

Problem:

It seems Django instantiate a dummy connector for default and then calls not implemented methods on this connector.

I am attaching the output log of the command.
Here is a sample project to reproduce the behaviour: ​​​https://github.com/trecouvr/test_dj_migrate_174.

[Marten Kenbeek]

I've opened a discussion on this on the mailing list: ​https://groups.google.com/forum/#!topic/django-developers/VWyP5M7cRyk

I feel this is more a design decision than a bug. The documentation states that default is required but not in which way. A strict interpretation would conclude that DATABASES['default'] = {} is sufficient, but I personally have always interpreted this as "default requires a valid database configuration".

[Marten Kenbeek]

It is indeed a bug, as the documentation on ​multi-db setups explicitly allows this.

[Tim Graham]

I've reviewed the ​pull request.

[Tim Graham <timograham@…>]

In e2bfcab:

Fixed #24394 -- Allowed running tests with empty default dictionary.

[Sjoerd Langkemper]

I filed a bug for similar behavior in Django 1.9a1: #25504