When writing Rails migrations, it is good to define, when possible, what should happen when migrating up and what should happen when migrating down. You’ll then want to check that both the up and down work. This can be accomplished using the following one-liner:

$ rake db:migrate && rake db:migrate:redo

The rake db:migration does what we would expect applying our new migration and showing us that our up works. The rake db:migrate:redo first performs a rollback, showing us that our down works, and then migrates back up again. We now know that our latest migration works going both directions.