multi_db flag on TestCase causes invalid error reporting when loading fixtures.

[David Cramer]

When setting multi_db = True on a test case you may encounter aliases which do not allow synchronization with specific tables. Due to the behavior of the fixture loader, it sees that no objects were loaded for these specific aliases and prints an exception to stderr and runs a rollback command.

The chunk of code in reference is here ​http://code.djangoproject.com/browser/django/trunk/django/core/management/commands/loaddata.py#L196

(For posterity, the 'if objects_in_fixture == 0:' error assumption is what causes this behavior)

[Russell Keith-Magee]

You appear to be describing a situation where a test database can't synchronize all the tables it should have, and as a result, fixture loading fails.

For my money, that situation *should* raise errors.

I'm not sure I see how this is related to multi-db. Setting multi-db=True increases the number of databases that will be synchronized, but it doesn't change the way individual databases are synchronized. If you get this problem with multi-db, you should be able to reproduce it with a single database under the right conditions.

Closing invalid; if I've missed the point, feel free to reopen and provide more detail. For the record, you should also feel free to provide sufficient detail when you open a ticket in the first place :-)

[Russell Keith-Magee]

Following discussion with David on IRC:

The actual problem here is a fixture that contains many valid objects, being synchronized onto a database where none of the models for those objects exist. E.g., I have a fixture with 10 Author objects; the Author table isn't synchronized onto 'other', but I'm loading Author onto 'other'. There are 10 valid objects, but 0 "loaded" objects, which raises an error during test case fixture loading.

[Mariusz Felisiak]

As far as I'm concerned this is a duplicate of #16713.