# ActiveJob::SerializationError: Unsupported argument type: ContactForm# ./app/models/contact_form.rb:22:in `process' # ./spec/models/contact_form_spec.rb:20:in `block (3 levels) in <top (required)>' # ./spec/models/contact_form_spec.rb:23:in `block (3 levels) in <top (required)>'

contact_form.rb

# Form object for contact form
class ContactForm
  include ActiveModel::Model

  attr_accessor(
    :name,
    :email,
    :phone,
    :message
  )

  validates :name, presence: true
  validates :email, presence: true
  validates :phone, presence: true
  validates :message, presence: true

  # If the user input is valid, will deliver the details in a message in an email.
  def process
    return unless valid?
    MarketingMailer.contact(self).deliver_later
  end
end

contact_form_spec.rb

# frozen_string_literal: true

require 'rails_helper'

RSpec.describe ContactForm, type: :model do
  let(:contact_form) { build(:contact_form) }

  describe '#process' do
    subject { contact_form.process }

    it { expect(subject).to change { ActionMailer::Base.deliveries.count }.by(1) }
    it { expect(subject).to receive(:valid?) }
  end
end

# ActiveJob::SerializationError: Unsupported argument type: ContactForm
# ./app/models/contact_form.rb:22:in `process'
# ./spec/models/contact_form_spec.rb:20:in `block (3 levels) in <top (required)>'
# ./spec/models/contact_form_spec.rb:23:in `block (3 levels) in <top (required)>'

marketing_mailer.rb

# Mailer to handle marketing website requirements
class MarketingMailer < ApplicationMailer
  # Contact form email to admin
  # @param form [ContactForm] the form object submitted by the user
  def contact(form)
    @form = form
    mail to: 'admin@project.com', reply_to: form.email, subject: 'TestProject: Contact Submission'
  end
end