Fake an active record model without db

Question

I feel like I've got to me missing something. I'm writing a ruby gem that allows interaction with active record as an add on to its primary function.

In writing test cases for it, I need to be able to specify dummy active record models to test this functionality. It would be superb if I could get an instance of an active record model that didn't need any connection to a db, that could have relations, all that stuff, but didn't require me to setup tables in a database. I'm fairly new to testing, and outside of rails testing i'm pretty dang new, but it seems like I should be able to do something like that fairly easily, but I'm not finding anything.

Can anyone tell me what I'm missing? I've looked at factories, fabricators, fixtures, all those seem to want to hit the db. How do people test gems where you need AR object only for testing?

Answer 1

It sounds like you need NullDB:

NullDB is the Null Object pattern as applied to ActiveRecord database adapters. It is a database backend that translates database interactions into no-ops. Using NullDB enables you to test your model business logic - including after_save hooks - without ever touching a real database.