Today I had an error message driving me crazy:

 `method_missing': undefined method `export_format' for XXX model

You see, our model is a gem itself, because it is shared by several projects. When we have something in the schema that is not in the database, that is the error we get.

Now, I knew this error from previous executions, but my model was in synch with the DB.

I tried to comment out all my changes, without luck.

Until I realized. This error was in my specs.

I had run the rake db:migrate, but not RACK_ENG=test

In this situation I was happy I fixed the issue, but at the same time extremely angry I wasted 1h with that

Mental note: run both friggin migrations together in the future!

This might help:

alias migrate='rake db:migrate; rake db:migrate RAILS_ENV=test'

thanks to Eumir for this post