The has_many_polymorphs plugin is finicky: order of operations is important! If you have problems with your associations after installing HMP, play around with the order of your has_many associations and such.
Also, “type is not type”: has_many_polymorphs’ use of the type column is not the same usage of Single Table Inheritance’s (STI) usage of type. If you are using HMP for an ActiveRecord using STI (say, “Student” which extends “Person”), HMP needs to reference the base class/table, not the subclass (i.e. reference Person, not Student.)
If your Rspec test seem to be having problems finding the Models, Controllers, etc. that are the test subjects, make sure the directory ‘spec test structure is correct: “model” for model tests, “controller” for controller tests, etc. Rspec assumes that these test directories exist.
Finally, as if you didn’t need to be told so, ActiveRecord will have problems if you create a table with only an id column.