How to test module using concerns and associations, via dummy ActiveRecord model in specs

Question

What is the best way to test a module that uses associations, with a dummy active record class?

module Outputable
  extend ActiveSupport::Concern

  included do
    has_one :output, as: outputable
  end

  delegate :print, to: :output
end

To use this module in a class, you'd make a new ActiveRecord model:

class Program < ActiveRecord::Base
  include Outputable

  def initialize(output)
    self.output = output
  end
end

prog = Program.create(Output.create)
prog.print("hello world") # delegates to Output.print

I want to be able to use several types of classes, for example Program, Log, etc. But I have not defined these ActiveRecord models yet, I'd like to test with a dummy class in specs (similar to this SO question). I've tried the Temping gem, but maybe it is outdated, using Rails 4, Ruby 2.1.2 I get:

when trying to do DummyProgram.create(output) from:

Temping.create :dummy_program do
  include Outputable

  def initialize(output)
    self.output = output
  end
end

describe Outputable
  let(:output) { Output.create }
  let(:prog) { DummyProgram.create(output) }

  it "exposes Output methods" do
    expect(output).to receive(:print)
    prog.print("hello world!")
  end
end

I get a strange undefined method '[]' for nil:NilClass method for the DummyProgram.create(output). It works how ever if I do DummyProgram.new(output) but I need it to be saved to the temporary db.

Has anyone encountered a way around this, or an alternative to temping gem?

Update: For now, I'm going with manually creating and dropping a table:

describe Outputable do
  let(:output) { Output.create }
  let(:prog) { DummyProgram.create(output: output) }

  class DummyProgram < ActiveRecord::Base
    include Workflows::Outputable
  end

  before :all do
    m = ActiveRecord::Migration.new
    m.verbose = false
    m.create_table :dummy_program do |t|
      t.integer :workflow_id
      t.string :workflow_type

      t.timestamps
    end
  end

  after :all do
    m = ActiveRecord::Migration.new
    m.verbose = false
    m.drop_table :dummy_program
  end

  ...
end