South and mutiple databases tests¶

Tags: django

Ok, today was the second time I was bitten by this. Time to write down the solution so I can find it back in google :-)

The problem occurs when you have multiple databases, with the second one being just for one app. For example an existing database from the customer with some read-only data. So you probably have one app just for reading that data with a database router that allows only that app’s models in that database. What happens when you have south enabled and you run the tests:

$> bin/test
...
Creating test database...
Syncing...
Creating table aaa
Creating table bbb
...
No fixtures found.
Migrating...
Running migrations for ccc:
 - Migrating forwards to 0001_initial.
...
No fixtures found.

Synced:
 > aaa
 > bbb

Migrated:
 - ccc

Creating test database 'the_second_database'...
Syncing...
Creating table ddd
Creating table eee
No fixtures found.
Migrating...
Traceback (most recent call last):
...
django.db.utils.DatabaseError: no such table: south_migrationhistory

Well, yes, that south_migrationhistory table doesn’t exist in the second database. It doesn’t need to be. When creating/migrating the databases (outside the tests), it all goes perfectly OK as only the default database is getting created/migrated. Only south in combination with tests fails as both databases need to be created/migrated to run the tests.

The workaround: add SOUTH_TESTS_MIGRATE = False to your settings.py to switch off south usage during tests.

I read that south’s multiple database support isn’t fully matured. The routers aren’t used yet for autodetecting the proper behaviour, for instance, in so far that would be possible. Anyway, the workaround works for now :-)

I’ve opened a ticket for it.