Weird behavior...

base_job.rb

class BaseJob < ActiveRecord::Base

  belongs_to :child_job, polymorphic: true

  has_attached_file :header_image, :styles => { :medium => "800x500#" }
  validates_attachment_content_type :header_image, :content_type => /\Aimage\/.*\Z/

  validates :title, presence: true
  validates :prompt_html, presence: true

end

link_job.rb

class LinkJob < ActiveRecord::Base
  include BaseJobMethods

  has_one :base_job, as: :child_job
  has_many :job_completions, as: :job
  belongs_to :redirector

  accepts_nested_attributes_for :base_job

  validates :base_job, presence: true
  validates :redirector, presence: true

  
  def completed_by_user?(user)
    false if user.nil?
    user.has_completed_job?(self)
  end

  def has_user_met_requirements?(user)
    false if user.nil?
    user.redirector_clicks.where(redirector_id: redirector.id).exists?
  end

end

link_job_spec.rb

require 'rails_helper'

RSpec.describe LinkJob, type: :model do
  it { should validate_presence_of :base_job }
  it { should validate_presence_of :redirector }
  it "should return true when asked if it is #persisted?" do
    link_job = create(:link_job)
    expect(LinkJob.count).to eq(1)
    expect(link_job.redirector.persisted?).to eq(true)
    expect(link_job.base_job.persisted?).to eq(true)
    expect(link_job.new_record?).to eq(false)
    expect(link_job.destroyed?).to eq(false)
    expect(link_job.persisted?).to eq(true) # fails here...
  end
end

redirector.rb

class Redirector < ActiveRecord::Base
  has_many :redirector_clicks
  has_one :link_job
end

This presented itself when I went to edit a link job, which is set up as a regular resource in rails. The form fields fill out properly. But the persisted? method doesn't return true, even though the link_job record has been persisted. This could be related to rails/rails#13744 - I haven't looked very far into this, as I'm expecting I'm doing something that is just a bad pattern and maybe we need to refactor our relationship between the base job and the link job, or something like that... Baffling, though, as that test passes all the way up to the final line.

(The thing that led me to this was the fact that the form submission caused what looked like a duplicate record, but in fact was due to the form having the new link_jobs path set on it, then I tracked it down to the persisted method by looking at the form_for helper itself to determine which path it drops into resource forms.)

As it turns out, the include BaseJobMethods line referenced a module that included ActiveRecord::Base. Removing that inclusion fixed the issue.