association.is_working_properly?

When working with a team on a project things can get quickly out of sync. However, when working with a geographically seperated team, things can get out of sync before it even happens -- quick. With source control and high level languages of today, being disorganized amongst team members is much better than it was a few years ago, but still still happens just as much.

Things can go wrong while working on a team like this and usually do, quickly like I stated previously. One area they can go wrong is with migrations. This is where an issue can pop up when creating an association between your domain models.

manufacturer = Manufacturer.new(:name => "Chevrolet")
manufacturer.models.build(:name => "Corvette")
manufacturer.models.build(:name => "S10")
manufacturer.save

In Rails, they're supposed to just work and most people can continue building their application without testing to make sure a "model" is associated (added to) a "manufacturer". The issue is if someone on your team blindly creates a migration and checks it in because they think they're a "guru" and don't need to test or run tests before checking-in. This is a major-fail. This problem happened in my current project and stopped development which pissed me off since my pair and I had to go back and fix someone else's mistakes when we should have been able to continue on with the features we needed to implement.

When creating an associated domain model there's usually some sort of change that needs to happen to the database. This interaction or creation of, is created by a human -- you or me.  It's in the form of a migration as well.  The human element introduces a point of failure so it must be tested, even if it's something minor like adding a column that is used by the framework.

The moral of this story is, test everything if a human has changed the state of it.