MissingAssociationClassChecker

Sometimes, your associations point to an undefined model. That could be fine if you don't use those associations anymore. However, it's always good to clean them up for the codebase or to fix them by specifying a class_name or generating a model.

Example:

class User < ApplicationRecord
  has_many :something
end

If no Something model exists in your codebase, database_consistency will find it.

P.S. The check is not supported by polymorphic associations.