reproduce.rb

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  # Activate the gem you are reporting the issue against.
  gem "activerecord", "6.0.0"
  gem "sqlite3"
  gem "paranoia", "~> 2.4", ">= 2.4.1"
end

require "active_record"
require "minitest/autorun"
require "logger"

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :posts, force: true do |t|
    t.string :name
    t.string :slug, null: false
    t.time :deleted_at
  end
end

module Sluggable
  extend ActiveSupport::Concern

  included do
    before_create :set_slug

    def generate_slug(payload)
      slug = payload.underscore.tr("-", "_")

      if self.class.where(slug: slug).exists?
        "#{slug}_#{SecureRandom.hex(6)}"
      else
        slug
      end
    end

    def sluggable_value
      name
    end

    private

    def set_slug
      self.slug = generate_slug(sluggable_value) if slug.blank?
    end
  end
end

class Post < ActiveRecord::Base
  include Sluggable

  acts_as_paranoid
end

class BugTest < Minitest::Test
  def test_association_stuff
    Post.find_or_create_by!(name: "test")
    # here we see a deprecation message
  end
end