Depends. For apps that I distribute generically for use with Django, I usually stick only to ORM features that are supported across all backends. And then I ju

Depends. For apps that I distribute generically for use with Django, I usually stick only to ORM features that are supported across all backends. And then I just have tox set up to run the tests with an in-memory SQLite database, since that's fast (and Django's test suite already exercises its ORM on all the backends, so I can trust the ORM will work on other DBs). My personal blog, though? I run Postgres locally on my laptop (via Postgres.app) to make the dev/testing environment as similar as possible. Most places I've worked have done similarly, running either Postgres or MySQL locally, and I have run into bugs that only manifested on MySQL (not because of bugs in Django, but because of MySQL acting in the way MySQL acts).