How to Deal with 1,000 Failing Specs in a Rails App

A few months ago, Planet Argon kicked off a Rails 2.1 to Rails 3.0 / Ruby 1.8.7 to Ruby 1.9.3 upgrade for one of our clients. The monolithic Rails app contained over 1 million lines of code and accumulated over 9,000 RSpec tests throughout its decade of development. Once the test suite was running on the new version, 8,000 of these specs failed.This blog post is a collection of my lessons learned while tackling this upgrade in hopes you may be better prepared to fearlessly face 1000 failing specs. We’ll cover what to do when facing 1000 failing specs, and then move on to learning what to do to prevent 1000 failing specs in the future.