There was no backtrace to speak of. I now think I understand what has happened. Follow this and see if I am on the right track…
I started with a GREEN rspec run.
I wrote a test to validate a new field on my model. Rspec is RED.
I created the migration and ran the rakes. Rspec is now GREEN.
I wrote a validation to test the presence of the new field. Rspec is RED.
I added the validate in the model.
At this point I was expecting a GREEN rspec run. However, it was red with the error above. I think it was telling me that factory that was initially created is not not valid because I never updated it with the new required field. Being new, I did not think it all the way through.