Question

I have a app that is deployed to Heroku, and I’d like to be able to run the test suite post-deployment on the target environment. I am using the Heroku Postgres add-on, which means that I have access to a single database only. I have no rights to create new databases, which in turn means that the standard Django test command fails, as it can’t create the test_* database.

$ heroku run python manage.py test
Running `python manage.py test` attached to terminal... up, run.9362
Creating test database for alias 'default'...
Got an error creating the test database: permission denied to create database

Is there any way around this?

Answer 1

Turns out I was in the wrong. I was not testing what I thought was being tested… Since Heroku’s Routing Mesh was sending requests to different servers, the LiveServerTestCase was starting a web server on one machine and Selenium was connecting to other machines altogether.

By updating the Heroku Procfile to:

web: python src/manage.py test --liveserver=0.0.0.0:$PORT

overriding the DATABASES setting to point to the test database, and customizing the test suite runner linked to below (the same idea still holds: override setup_databases so that it only drops/re-creates tables, not the entire database), I was able to run remote tests. But this is even more hacky/painful/inelegant. Still looking for something better! Sorry about the confusion.

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(updated answer below)

Here are the steps that worked for me:

• Create an additional, free Postgres database using the Heroku toolbelt

heroku addons:add heroku-postgresql:dev

• Use the HerokuTestSuiteRunner class which you’ll find here.

This custom test runner requires that you define a TEST_DATABASES setting which follows the typical DATABASES format. For instance:

TEST_DATABASES = {
    'default': dj_database_url.config(env='TEST_DATABASE_URL')
}

Then, have the TEST_RUNNER setting be a Python path to wherever HerokuTestSuiteRunner can be found.

You should now be able to run Django tests on Heroku using the given database. This is very much a quick hack… Let me know how it could be improved / made less hackish. Enjoy!

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(original answer below)

A few relevant solutions have been discussed here. As you can read in the Django docs, “[w]hen using the SQLite database engine, the tests will by default use an in-memory database”.

Although this doesn’t thoroughly test the database engine you’re using on Heroku (I’m still on the lookout for a solution that does that), setting the database engine to SQLite will at least allow you to run your tests.

See the above-linked StackOverflow question for some pointers. There are at least two ways out: testing if 'test' in sys.argv before forcing SQLite as the database engine, or having a dedicated settings file used in testing, which you can then pass to django manage.py test using the --settings option.