Monthly Archives: May 2012

Running Django unit tests on PythonAnywhere

21 May 2012

I was working on a side project today, a Django app hosted at PythonAnywhere. While writing some initial unit tests, I discovered a confusing bug. When you try to run the tests for your app, you get an error message creating the database (for the avoidance of doubt, USERNAME was my PA username):

18:57 ~/somewhere (master)$ ./manage.py test
Creating test database for alias 'default'...
Got an error creating the test database: (1044, "Access denied for user 'USERNAME'@'%' to database 'test_USERNAME$default'")
Type 'yes' if you would like to try deleting the test database 'test_USERNAME$default', or 'no' to cancel: no
Tests cancelled.

The problem is that PythonAnywhere users don’t have the privileges to create the database test_USERNAME$default (whose name Django’s unit testing framework has auto-generated from the USERNAME$default that is the DB name in settings.py). PA only allows you to create new databases from its web interface, and also only allows you to create databases that are prefixed with your-username$

After a bit of thought, I realised that you can work around the problem by setting TEST_NAME in settings.py to point to a specific new database (say, USERNAME$unittest) and then creating a DB of that name from the MySQL tab. Once you’ve done that, you run the tests again; you get an error like this:

19:02 ~/somewhere (master)$ ./manage.py test
Creating test database for alias 'default'...
Got an error creating the test database: (1007, "Can't create database 'USERNAME$unittest'; database exists")
Type 'yes' if you would like to try deleting the test database 'USERNAME$unittest', or 'no' to cancel:

You just enter “yes”, and it will drop then recreate the database. This works, because when you created it from the MySQL page, the settings were set up correctly for you to be able to create and drop it again in the future. Once this has been done once, tests run just fine in the future, with no DB errors.

Obviously we’ll be fixing this behaviour in the future (though I can’t offhand see how…). But there’s the workaround, anyway.